Part 9

Footnote 31: Read to the Geological Society of France, at their meeting on the 16th of April 1849.

Again, to bring to your recollection the numerous works which have placed Pilla among the most eminent geologists of Italy, is to do honour to the memory of an associate, whose recent loss we lament, by bestowing well-merited praises on the greatness of mind in a citizen, who nobly sacrificed a life already illustrious, and which the future promised to render still more so, to the good of his country. Yes, Italy has always been _tellus magna virum!_ The chances of war, the rage of civil discord, the insults of foreign domination, may have eclipsed its political name, but they could not extinguish its genius. The blast of revolutions has respected the triple halo with which the sciences, letters, and the arts, have adorned its brow. By entrusting to one of his friends the task of enumerating his scientific labours, the Society imposes on him a very painful duty; but he undertakes it with feeling and gratitude; for the public homage rendered to the virtues of those whom we have loved, seems to bring them back to us, and softens the awards of destiny, which has too soon snatched them from us.

Leopold Pilla was born in the kingdom of Naples. While still young, the exciting scenes of Vesuvius attracted his attention, and determined his scientific career. In 1832, he undertook to write the annals of this volcano, and gave its history in two periodical collections.[32] It was at this period that he proved the production of flames in volcanic eruptions, and deduced from thence the ingenious conclusions which you judged worthy of a place in your memoirs.[33] This remarkable work, which of itself would have been sufficient to establish his scientific reputation, was soon followed by numerous others, which shed a new lustre on his name. The study of the extinct volcano of Rocca Monfina,[34] in the Campania, illustrated the theory of craters _de soulevement_, and enriched it with facts of the highest importance.

Footnote 32: Spettatore del Vesuvio et Bulletino del Vesuvio. Napoli, 1832.

Footnote 33: Sopra la produzione delle fiamme nei vulcani, e sopra le consequenze che se ne possono tirare. Atti del Congresso di Lucca, 1845.

Footnote 34: Memoires de la Société Geologique de France, t. i., 2me serie.

With a mind at once philosophical and cultivated, he was able to generalise and describe, to unite erudition with good taste, and to treat questions of deepest science with that grace and picturesqueness of style, which renders them popular without detracting from their accuracy. His love for geology amounted to enthusiasm; he was therefore so zealous in propagating his views, that certain jealous minds could not pardon him, and led him to atone for his fault, by a voluntary exile. The apostle of the science, he likewise was its martyr; thus nothing was wanting to his fame. It is the privilege of men of genius to be persecuted. Obliged to yield to the storm, Pilla left Naples, but by his writings he belonged to Italy at large; and the unanimous acclamation which greeted him in the chair formerly occupied by Galileo, conferred on him by the liberality of the Grand Duke of Tuscany, formed at once his triumph and revenge.

Besides the works mentioned, we owe to him a Mineralogical Treatise on Rocks;[35] an Introduction to the Study of Mineralogy;[36] and a Geological Itinerary from Naples to Vienna.[37] Thus, by approving the new productions which his activity produced, and which caused him to be better appreciated by the nation which had adopted him, the Tuscans had only to sanction the judgment they had already given of our _savant_, founded on his reputation and works.

Footnote 35: Trattato mineralogico delle Roccie, Napoli.

Footnote 36: Introduzione allo studio della geologia, Napoli.

Footnote 37: Osservazioni Geologiche che si possono fare lungo la strada da Napoli a Vienna.

Pilla left his heart at Naples. That city contained all the objects of his affections--a father, who had guided his first attempts in the field of science, and his family--a classical soil which had revealed to him the secret of its revolutions, a majestic landscape, which he could not find among the monotonous plains of Pisa, and above all _his own_ Vesuvius. It was in this way that he recalled to his mind the mountain which had been the subject of his daily study, and from whose summit nature presented herself to his eyes in the most striking contrasts, revealing to his view its subterranean convulsions, connected with the delightful picture of the Gulf of Baia. All his thoughts brought him back to Naples. When, from the height of the terraces of Campiglia our view extended from the peaks of Mount Amiata to the banks of the Popolonia, and from the Tuscan Archipelago to the distant horizons of Corsica and Sardinia, my poor friend often interrupted our reveries by saying,--"It is almost as beautiful as Naples, but my Vesuvius is wanting;" and then adding, "How unfortunate it is that Werner did not lay the foundation of geology at Naples; _he would have made it Plutonian_." Thus the love of his country, and the recollection of its wonders, were confounded in his mind with the cultivation of the science, and gave to his animated and poetical conversation a touching melancholy which agreeably tempered his vivacity.

During the years of his professorship at Pisa, Pilla published, in succession, a comparative Essay on the formations which compose the soil of Italy;[38] a Collection of the Mineral riches of Tuscany;[39] two Memoirs on the Etrurian Formation;[40] History of an Earthquake felt in Tuscany, in 1846;[41] many notices respecting the Calcare-rosso, and on the temperature observed in the wells of Monte-Massi;[42] lastly, the first volume of his Treatise on Geology.[43] The entire work would have formed four octavo volumes. The materials were prepared, but death left the work incomplete. As these various writings are in the hands of all geologists, we give no analysis of them; which indeed would only be a faint reflection from the pictures present to your memory. I may merely say, that the elevated considerations of the general physics of the globe to which he has risen in appreciating and investigating the causes of earthquakes, the comprehensive and methodical plan on which he has projected this geological treatise, by affording us a proof of the fertility and maturity of his mind, shew us, at the same time, the importance of the part reserved for a philosopher, whom death has removed from the present scene before he had reached his thirty-sixth year.

Footnote 38: Saggio comparative dei terreni che compongono il suolo de l'Italia, Pisa.

Footnote 39: Breve cenno sopra la richezza mineralogica della Toscano, Pisa.

Footnote 40: Sulla vera posizione del terreno di macigno in Italia, Pisa; and Memoires de la Société geologique de France, 2me serie, t. ii.

Footnote 41: Storia del tremuoto che ha devastuto i paesi della costa Toscana, il di 14 Agosto 1846, Pisa.

Footnote 42: Miscellanee di fisica e di Storia naturale di Pisa, anno 1, Nos. 7 and 8.

Footnote 43: Trattato di geologia, t. i., Pisa, 1847.

The war of independence raged at the time when Pilla was about to visit the north of Europe, in order to complete his studies in practical geology, by comparing the different formations. Every generous heart in Italy beat high at the report of the insurrection of Milan; and the Universities of Pisa and Sienna, by demanding arms and first flying to the scene of danger, shewed that hearts, proved in the fire of science, are prepared for great things. Pilla marched at the head of his pupils, and led them in the path of glory, as he had done in that of philosophy. The love of country and thirst for independence, by subjugating his heart, had stifled the calculation of reason under the impulse and delirium of enthusiasm. He had foreseen the issue of the struggle; for he said to me some days before setting out for the plains of Lombardy, "the hour of our fall has struck. Italy loses by fourteen ages of servitude the splendour of her early days. They are leading us to slaughter; but we must teach our children how to die, in order that they may know how they may one day become free."

The University legion formed a small corps which was placed on the right wing of the Piedmontese army, and occupied the positions of Curtatone and Montanara. The principal effort of the Austrian army was directed against these lines, in the affair of the 29th May 1848. Attacked by 13,000 imperial troops, the Tuscans resisted courageously, and did not fall back till they had left 250 of their men on the field of battle. Their heroic resistance paved the way for the success of Goito. Pilla was found among the dead.

_On the Chronological Exposition of the Periods of Vegetation, and the different Floras which have succeeded each other on the Earth's Surface._ According to the views of M. BRONGNIART.

(_Continued from p. 330 of Volume 48._)

"II. _Permian Period._--The nature of the vegetables which appear peculiar to this epoch, is far from being determined in a positive manner; for the few localities where the fossils we consider as belonging to it, have hitherto been found, are not perhaps really of a formation very identical and truly contemporaneous. For it may be asked, whether the bituminous and copper slates of the county of Mansfield, classed by all geologists with the zechstein, and the sandstone of Russia, placed by M. M. Murchison and Verneuil in their Permian formation, are really contemporaneous? Finally, is there greater reason for classifying the slates of Lodève, considered by M. M. Dufresnoy and Elie de Beaumont as depending on the variegated sandstone, but so different from the same sandstone of the Vosges in its _flora_, in this period, which would thus be a kind of passage from the coal period, so well characterised, to the vosgian or variegated sandstone, which differs from it in so decided a manner?"

On account of these doubts, M. Brongniart indicates these three floras separately; _1st_, The Flora of the bituminous slates of Thuringia, composed of algæ, ferns, and coniferæ; _2d_, The Flora of the Permian sandstones of Russia, which comprehends ferns, equisetaceæ, lycopodiaceæ, and noeggerathiæ; _3d_, The Flora of the slates of Lodève, which is composed of ferns, asterophylliteæ, and coniferæ.

"We perceive that there are great specific differences between the plants of these localities, and that hitherto no species common to them has been found. Must we ascribe these differences to the influence of the great diversity of geographical position, or is there, besides, a difference in the period of their origin among these formations? The only character which tends to bring these two latter Floras near each other, is the relation which both of them bear to the coal-formations, of which they seem to be a kind of extract, reminding us more especially of the most recent beds.

"With regard to the plants of the bituminous slates of the Mansfeld district, they are so few in number, and appear to have been deposited in conditions so different, that we can with difficulty compare them with the two other Floras. Yet the species of Sphenopteris are extremely like each other in the three formations, and an exact comparison would perhaps establish the identity of many of them. The Pecopteris crenulata of Ilmenau, is only perhaps an imperfect state of the Pecopteris abbreviata of Lodève; lastly, the Callipteris of the Permian formation of Lodève have a very close connection between themselves and the Callipteris of the coal-formation.

"We may add, with regard to the bituminous slates of Thuringia, that many of these fossils appear to be marine plants, whose numbers would become much more considerable if we did not suppress all the imperfect impressions which have been described as such, and which are nothing more than fragments of ferns or altered coniferæ.

"II. REIGN OF THE GYMNOSPERMS.--During the preceding periods, and particularly during the Carboniferous period, the Acrogenous cryptogams predominated, and the Gymnospermous dicotyledons, less numerous, shewed themselves in unusual forms, and sometimes so anomalous that we are in doubt whether to place them in this or the preceding department; such are the Asterophylliteæ. At a later period, on the contrary, these anomalous and ambiguous forms, whose classification is often obscure, disappear; Acrogenous cryptogams and Gymnospermous dicotyledons evidently enter into families still existing, differing from them only in generic forms; the Ferns and Equisetaceæ, which represent the acrogens, are less numerous; the Coniferæ and Cycadeæ almost equal them in number, and usually exceed them in frequency, especially in the second period; by their abundance and size they afford the essential character of all these formations; lastly, the Angiospermous dicotyledons are wholly wanting, and the monocotyledons are in very small numbers.

"This reign of the Gymnospermous dicotyledons is divided into two periods; the first, in which the Coniferæ predominate, and in which the Cycadeæ scarcely appear; the second, in which this family becomes predominating in the number of species, in frequency and variety of generic forms. The latter may be divided into many epochs, each presenting peculiar characters.

"III. _Vosgian Period._--This period, which does not appear to have been of long duration, and comprehends only the _variegated_ sandstone properly so called, presents the following characters; _1st_, The existence of ferns, pretty numerous, of forms very often anomalous, evidently constituting genera now extinct, and which are not found even in the most recent formations; such are the Anomopteris and the Crematopteris. Stems of arborescent ferns are more frequent than during the Jurassic period; true Equisetums are very rare; the Calamites, or rather perhaps the Calamodendrons, are abundant. _2d_, The Gymnosperms are represented by two genera of Coniferæ, _Voltzia_ and _Haidingeria_, of which the species and specimens are very numerous. The Cycadeæ, on the contrary, are very rare. M. Schimper mentions only two species founded on two unique specimens of a very imperfect character, and the determination of which may be considered doubtful.

"This consideration appears to me to separate completely, in a botanical point of view, the period of the variegated sandstone from that of the Keuper, although both are placed by geologists in the trias-formation. For the Cycadeæ become very abundant in the Keuper, are perfectly characterised, and often analogous to those of the Jurassic period; while the Coniferæ of the variegated sandstone are, on the contrary, wanting in this formation.

"IV. _Jurassic Period._--This period is one of the most extensive by the formations which it comprehends, and the variety of different special epochs of vegetation which it embraces; although we cannot refuse to comprehend, under a common title, epochs during which very analogous forms have succeeded each other. It thus comprehends from the Keuper inclusively, up to the Wealdean formations. In fact, we find the Pterophyllum of the Keuper appear anew, with slight specific differences in the Wealdean formations. The _equisetites_ of the Keuper extend to the mean oolithic formation; the _baiera_ of the Lias likewise recurs in the Wealdean beds of the north of Germany; the Sagenopteris and the Camptopteris likewise appear in the Keuper, Lias, and Oolite.

"Yet these common characters, which indicate a great analogy between the Floras of each of these epochs of formation, do not prevent each of them having characters of its own, and often an assemblage of species, almost all peculiar to each particular epoch. We ought, therefore, to distinguish here those various subdivisions, the number of which will perhaps be afterwards multiplied, when we become better acquainted with the vegetables of each of the stages of the Jurassic formations.

"_Keupric Epoch._--M. Brongniart then gives an enumeration of the vegetables of the Keupric epoch, which, in regard to the Amphigenous cryptogams, consist of Algæ; in regard to the Acrogenous cryptogams, of Ferns and Equisetaceæ; in the case of the Gymnospermous dicotyledons of Cycadeæ and Coniferæ; lastly, of two doubtful monocotyledons (_Palæoxyris_ and _Preisleria_.)

"On comparing this Flora with that of the variegated sandstone of the Vosges, and with that of the Lias, we perceive that it has nothing in common with the first except the palæoxyris, which appears very nearly related to that of the variegated sandstone; on the contrary, it resembles the Flora of the Lias or Oolite in the ferns, many of which are specifically identical, or nearly allied in the _Nilsonia_ and _Pterophyllum_, which are likewise either identical, or very nearly connected specifically with the Lias.

"_Lias Epoch._--The Liasic epoch furnishes Amphigenous cryptogams, consisting of Algæ, mushrooms, and lichens; Acrogenous cryptogams, such as Ferns, Marsileaceæ, Lycopodiaceæ, and Equisetaceæ; Gymnospermous dicotyledons, represented by the Cycadeæ and Coniferæ; finally, doubtful monocotyledons, consisting of _Proacites_ and _Cyperites_.

"The essential characters of this epoch are therefore, _1st_, The great predominance of Cycadeæ, already well established, and the presence of numerous genera in this family, particularly _Zamites_ and _Nilsonia_; _2d_, The existence of many genera among the ferns with reticulated nerves, which scarcely shew themselves, and under forms not greatly varied, in the most ancient formations; but some of which, notwithstanding, already begin to appear in the epoch of the Keuper. Such are the _Camptopteris_ and _Thaumatopteris_.

"_Oolitic Epoch._--The Oolitic epoch furnishes, among Amphigenous cryptogams, the Algæ; among the Acrogenous cryptogams, Ferns, Marsileaceæ, Lycopodiaceæ, and Equisetaceæ; among the Gymnospermous dicotyledons, Cycadeæ and Coniferæ; lastly, among the doubtful monocotyledons, Podocarya and Carpolithes.

"This list is chiefly founded on the fossils, so varied in character, collected on the coasts of Yorkshire, near Whitby and Scarborough, in beds which are referred to different parts of the inferior oolite, and particularly to the great oolite. It likewise contains a small number of species found in the slaty limestone of Stonesfield, near Oxford, depending on these same beds.

"In France, the fossils of this formation have been collected in the neighbourhood of Morestel, near Lyon, by Dr Lortet; at Orbagnoux and Abergemens, near Nantua, in the department of the Ain, by M. Itier; in the vicinity of Chateauroux, near Châtillon-sur-Seine, by Colonel Moret; at Mamers, in the department of Sarthe, by M. Desnoyers; and, lastly, in the greatest quantity by M. Moreau, in beds of oolithic limestone of a very pure white, in the neighbourhood of Verdun, and near Vaucouleurs. Some species have likewise been found at other points of the Jura, in Normandy, near Valogne, in the neighbourhood of Alençon, in each of these localities in very small number. But the greater part of these species are not yet described and figured, and they generally differ as species from those of England. The ferns are generally less numerous, and not so well preserved; we must, however, except the _Hymenophyllites macrophyllus_, found in a perfect state at Morestel, and likewise observed at Stonesfield, and in Germany. The Cycadeæ, the species of which are not greatly varied, are referrible to the genera _Otozamites_ and _Zamites_; Ctenis, Pterophyllum, and Nilsonia have not yet been observed; lastly, the Coniferæ of the genus _Brachyphyllum_ are there particularly abundant, and more frequent than in the other localities.

"In Germany, it is more especially in the slaty limestone of Solenhofen, near Aichstædt, that these fossils have been observed, and particularly those of the family of Algæ. M. Gæppert likewise notices many Cycadeæ in the Jurassic formation of Ludwigsdorf, near Kreuzburg, in Silesia.

"But these localities, so diverse, are referrible to very different stages of the Oolithic series, and perhaps will constitute, when they are better known, and more fully explored, distinct epochs.

"The distinctive characters of this epoch, comprising the whole extent we have assigned to it, from the Lias to the Wealdean formation exclusively, are; among the Ferns, the rarity of ferns with reticulated nervures, so numerous in the Lias; among the Cycadeæ, the frequency of _Otozamites_ and _Zamites_, properly so called; that is to say, Cycadeæ most analogous to those of the existing period, and the diminution of _Ctenis_, _Pterophyllum_, and _Nilsonia_, genera much more remote from living species; finally, the greater frequency of Coniferæ, viz., _Brachyphyllum_ and _Thuites_, much rarer in the Lias.

"_Wealdean Epoch._--This epoch affords, Amphigenous cryptogams, the Algæ; among Acrogenous cryptogams, Ferns, _Marsileaceæ_, and _Equisetaceæ_; among Gymnospermous dicotyledons, _Cycadeæ_ and _Coniferæ_; lastly, some Carpolithes as plants of a doubtful class.

"This enumeration results principally from discoveries made, in recent years, in the Wealdean formations of the north of Germany, at Osterwald, Schaumberg, Buckeburg, Oberkirke, &c., of which the fossil plants were first described by M. Ræmer, and afterwards in a more complete manner by M. Dunker, in his monograph of these formations. To these species must be added others, less numerous and varied, previously discovered in the _Wealds_ of England, near Tilgate Forest, and Hastings in Sussex, and which are so well described by M. Mantell."

This same formation has likewise been found in France, near Beauvais, by M. Graves, who observed there _Lonchopteris Mantelli_, and some other plants, of which M. Brongniart has not seen specimens, and which he quotes from Graves on the geology of the department of the Oise.

"These species, 61 in number, enumerated above, appear to be all peculiar to this formation, with the exception, perhaps, of _Baiera Huttoni_, which seems to be identical with the species of the Bayreuth Lias and Scarborough Lias; but their generic forms are almost all the same as those of the Lias and Oolitic formations. The Cycadeæ, however, already appear less numerous relatively to the ferns.

"We further observe, that this fresh-water formation, which, according to our view, terminates the reign of the Gymnosperms is connected, by the whole of its characters with other epochs of the vegetation of the Jurassic formation, and is distinguished from the Cretaceous epoch, which succeeds it, by the complete absence of every species which could be arranged among the Angiospermous dicotyledons, both in France and England, as well as in the deposits of northern Germany, so rich in varied species. On the contrary, in the lower chalk, cretaceous _glauconia_, the quadersandstein or planerkalk of Germany, we immediately find many kinds of leaves evidently belonging to the great division of Angiospermous dicotyledons, as well as some remains of palms, of which no trace is observable in the Wealdean deposits.

"I class among the Cycadeæ the stems of the Tilgate forest, formerly designated by the name of _Clatharia Lyellii_, and which I have considered as a stem related to the _Dracæna_. The whole of its characters, although the almost entire absence of the tissues prevents us examining its anatomy, appear to me to render this connection most probable, and particularly to indicate the relations between this stem and that of _Zamites gigas_ found at Scarborough.