Part 37

The animals in which meningopoliomyelitis has been found were three monkeys, two Canadian lynx, a bear and a raccoon; about a score of cords from other animals with some kind of palsy have been studied microscopically without discovering it. The following cases illustrate our material. The only instance of two cases in close relation concerns the lynx (_Felis canadensis_). They occupied the same cage and died twelve days apart. No symptoms were recorded until a few days before death when a general paralysis appeared, deepening to completeness on the day of death. No case occurred in neighboring cages. Doctor Rhein studied all these cases, and his notes are used for these records. Portions of the lumbar and cervical enlargements and of the thoracic regions of the cord were stained with hemalum and acid fuchsin and with thionin. The pia was slightly infiltrated. There was some cellular infiltration of the anterior septum, and the vessels here showed an increase in the nuclei of the walls and a slight perivascular infiltration. The pial infiltration seemed to be equally distributed in the entire circumference of the cord, although perhaps a little more marked over the anterior and posterior septa. The vessels of the gray matter were congested and the walls of the vessels in most part showed a proliferation of the nuclei. There were a few small hemorrhages into the gray matter, probably agonal. As compared with the human cord and the cords of monkeys, antelopes and dogs, there was an unusually large number of glia nuclei, which, if found in the human cord, would be looked upon as a proliferation process. In some cases these nuclei were heaped together in masses, and were evidently pathological. There was also, about the ganglion cells, some pericellular round cell infiltration, and this was more marked around a few cells which were almost entirely destroyed. The ganglion cells themselves were swollen. Some showed eccentric nuclei, and many of them stained poorly, while one or two showed distinct vacuolization. In one field a ganglion cell was partly destroyed by a recent hemorrhage. There were, however, a number of cells which appeared normal. This process seemed to be fairly distinct in the lumbar and cervical enlargements, but was not clearly demonstrated in the sections from the dorsal region. The cellular infiltration of the horns was evidently not leucocytic, but presented the appearance of a connective tissue proliferation. Although these are not the exact lesions found in poliomyelitis in the human animal, they are at least suggestive of the same process since the infiltrating cells are of the lymphatic or connective tissue types. There is no acute inflammatory leucocytic infiltrate.

A weeper cebus (_Cebus capucinus_) ever since he was received acted in such a peculiar manner, seeming to have only partial control of his movements, that he was known as the “Crazy Monkey.” There was no history of illness before death. Pathological diagnosis: Chronic enterocolitis, chronic adhesive pericarditis, early interstitial change in kidney, edema of lungs, meningitis and poliomyelitis. The pia of the paracentral cortex was thickened and was the seat of a round cell infiltration of moderate degree, the cells being of the mononuclear type. The blood vessels of the cortex were congested and the nuclei of the walls were increased. The round cell infiltration of the pia had in some places extended into the cortical layers. The pia surrounding the medulla oblongata was also the seat of a slight round cell infiltration. The pia of the spinal cord, however, did not show any cellular infiltration. The cells of the anterior horns of the spinal gray matter were extensively diseased, being swollen in places, some surrounded by a glia proliferation and many with marked vacuolization.

A common raccoon (_Procyon lotor_) was observed in the laboratory to have complete paralysis of the anterior and partial paralysis of the posterior extremities. This latter was almost complete in muscles controlling the feet, while the thigh and hip muscles showed some irregular incoördinate movements. Respiration shallow but regular. History shows that the power of the extremities began to fail about a month before death and was absolutely lost in the fore extremities three days before the animal was killed. Diagnosis: Poliomyelitis. Examination of the central nervous system showed the presence of marked round cell infiltration of pia of cortex and of spinal cord, more particularly in the lower thoracic and lumbar regions. Ganglion cells in the lumbar region were markedly diseased. There were numerous old and fresh hemorrhages and a moderate degree of round cell infiltration in the anterior horns. Two young of this animal, born three months before its death, showed weakness and gradual increasing paralysis of their extremities beginning when three months old (that is at the time of the death of their mother), and lasting until their death, one in the seventh and one in the eighth month of life. These were found not to have changes in the central nervous system, but there was sufficient rachitis to account for this paralysis.

The only tumor of the central nervous system found among these animals occurred in an Undulated Grass Parrakeet (_Melopsittacus undulatus_). The gross notes are very vague but the microscopy is suggestive of a glioma. The growth in the brain consists of large irregular masses of large cells with vesicular nuclei and pale homogeneous protoplasm. “Scattered between these accumulations are irregular strands of spindle cells, with spindle-shaped nuclei, taking the hematoxylin very deeply. The supporting tissue is almost without cells, taking the eosin faintly, and is quite loosely arranged. No fibrils are seen among the cells. The blood vessels are congested, and at one place there is a small hemorrhage. The vessel walls are the same as the rest of the connective tissue. There is a slightly atypical metastasis in the liver.”

A case, the identity of which is still undecided, was observed in a Green Monkey (_Cercopithecus callitrichus_); it may belong among the gliomata or glioses. There was in the middle of this monkey’s cerebrum a gray area about 3 × 2 × 1 cm. with a softened centre, the more solid parts being found under the microscope to consist of glia tissue, blood vessels and degenerated cells. No true gliomatous formations could be discovered. Because of the indefiniteness of the lesion, it is not included in the tumors or inflammations. Clinically the effect of the change was to cause blindness and ataxia but motor power was not greatly impaired.

A very small number of tumors of the brain in wild animals is on record in the English and German literature, perhaps the most interesting being what resembles in description a subdural neurocytoma reported by Wilson in the _Proceedings of the London Zoological Society_, 1908. The mass was separate from the cerebellum, but had hollowed out a place for itself in this part of the hind-brain.

BRAIN WEIGHTS.

The policy of preserving the brain of all species enables us to record in the accompanying list the weights of a large number of specimens. In order that the figures may have a representative and comparative value only those are given where the total body weight of the animal is also known. The specimens were removed by the laboratory staff, most of them by one person, and by the same technique. All brains were weighed immediately upon removal from the body, no preservative being near the organ. The brains were themselves externally normal. Our technician is skillful in removing the organ, practically always getting the pituitary body, and cutting off the brain stem at the foramen magnum, the pia remaining but the dura removed. Because the specimens were taken, in practically all cases, from animals that died in the Park, and because of the shortness of the list (196), it seems wise not to attempt conclusions referable to comparative weights of the different orders and families. However, the data seem worthy of record because it is doubtful if anywhere one can find so many weights taken under comparable conditions by the same personnel. One can find a considerable list of brain weights and values in many publications throughout the literature, notably in an article by Ziehen in Bardeleben’s _Handbuch der Anatomie_ (Vol. IV, Abt. III 363), but from no single source are there so many varieties or so long a list. Ziehen’s tables are compiled from the literature and therefore represent data collected under different conditions, many of which were probably pathological. The appended figures are to be considered as raw material collected under uniform conditions.

Examination of the figures bears out in a measure some of the remarks made by Ziehen, notably those which indicate that between large and small varieties of the same general group, the smaller has the greater brain weight value and that the youthful animal has more brain than the adult.

The brains at the museum are fixed in saline-formaldehyde—sufficient strength of the former to suspend the organ in the container and four percentage of the latter. When fixation is complete, as indicated by density, preservation is done in one per cent. formaldehyde, the organ, usually bound in gauze, being laid in cotton. A list of important references is added to the weight tables—some antedating Ziehen’s articles, but principally those that have appeared since the publication of his monograph.

PRINCIPAL REFERENCES TO THE RELATIVE WEIGHT OF THE BRAIN

ZIEHEN: In _Bardeleben’s Handbuch der Anatomie des Menschen_, Vol. 4, pt. 3. ZIEHEN: _Handbuch der Anatomie des Nervensystems_, Jena, 1903. GIRARD: _Bulletin de l’Institut Gen. Psychologie_, Vol. 7, p. 53. VON BUSCHAU: _Real Encyclopedie der Gesamten Heilkunde 3. Aufl._ VON BUSCHAU: _Neurologisches Zentralbl._, 1897, March. BRANDT: _Bull. de la Soc. Imperial des Naturalistes de Moscow_, 1867, 40, pt. 2, 525. MIES: _Verhandl. der Gesellsch. deutscher Naturforsch und Arzte_, 1898, 353. DHERE ET LAPICQUE: _Archives de la Physiologie_, October, 1898. LAPICQUE ET GIRARD: _C. R. des Sceances de l’Academie de Science_, Paris, 1905, 140, 1057. LAPICQUE: _Bulletin de Museum d’Histoire Naturelle_, 1909, No. 7, 408. LAPICQUE: _Revue du Mois_, Paris, April, 1908, 445. LAPICQUE: _Bulletin et Memoires de la Société d’Anthropologie de Paris_, 1907, 5, Vol. 8, No. 3, 261. LAPICQUE: _Biologica_, Vol. 2, 1912, p. 257. FUNK: _Inaug. Dissert. Wurzburg_, 1911. POYNTER: _Cerebral Anthropology_, Lincoln, 1913. MOLLISON: _Arch. für Anthropologie_, 1914, XIII, 388. HULTGREN: _Das Hirngewicht des Menschen_, Upsala, 1912. WEBER: _Festschrift für Karl Gegenbauer_, 1898. DUBOIS: _Bulletin de la Soc. Anthropologie_, Paris, 1897, 337. DUBOIS: _Archiv. für Anthropologie_, Vol. 25, 1898. DUBOIS: _Proc. Sci. K. Acad. Wet., Amsterdam_, 1914, 16, 647. DUBOIS: _Zeitschrift für Morph. und Anthropologie_, 1914, Vol. 18, 323. MARCHAND: _Hirngewicht des Menschen_, Leipsig, 1902. RUDOLPH: _Beiträge zur Path. Anatomie_, Jena, 58, 1914, 48. KRAEMER: _Mitt. der Deutsch. Landwehrgesell_, 29, 1914, 55.