The works of Francis Maitland Balfour, Volume 1 (of 4)

The earliest stages in the development of the excretory system have already been described in a previous chapter[335] of this memoir, and up to the present time no investigator,...

In the embryos or larvæ of all the Elasmobranchii, Ganoidei, and Teleostei which have up to this time been studied, the unpaired fins arise as median longitudinal folds of the i...

_General History._ In stage G the brain presents a very simple constitution (Pl. 8, fig. G), and is in fact little more than a dilated termination to the cerebro-spinal axis. It...

Owing to this fact the first appearance of the external gills forms a very convenient break in the Elasmobranch development; and in the present chapter the history is carried on...

In the last chapter the blastoderm was left as a solid lens-shaped mass of cells, thicker at one end than at the other, its uppermost row of cells forming a distinct layer. Ther...

The alimentary canal of _Peripatus capensis_ forms, in the extended condition of the animal, a nearly straight tube, slightly longer than the body, the general characters of whi...

In the cases of Pristiurus and Scyllium only have I had any considerable number of eggs in this condition, though one or two eggs of Raja in which the process was not completed...

The development of the spinal nerves has been already treated by me at considerable length in a paper read before the Royal Society in December, 1875[247], and I have but little...

The present chapter deals with the early development of the heart, the development of the general circulatory system, especially the venous part of it, and the circulation of th...

[The remarkable discoveries about the early development of Peripatus, which Balfour made in June last, shortly before starting for Switzerland, have already been the subject of...

The change already alluded to in the previous chapter (p. 317) by which the external epiblast or epidermis becomes divided into two layers, is completed before the close of stag...

The present chapter deals with the history of the development of the Elasmobranch embryo from the period when the medullary groove first arises till that in which it becomes com...

The first development and early histological changes of the notochord have already been given, and we may take up the history of the vertebral column at a period when the notoch...

The present Chapter completes the history of the primitive alimentary canal, whose formation has already been described. In order to economise space, no attempt has been made to...

No complete series of figures, representing the various stages in development of an Elasmobranch Embryo, has hitherto been published. With the view of supplying this deficiency...

My investigations on the histology of the ripe ovarian ovum have been made with the ova of the Gray Skate (_Raja batis_) only, and owing to a deficiency of material are somewhat...

The nature and homologies of the ribs of Fishes have long been a matter of controversy; but the subject has recently been brought forward in the important memoirs of Götte[524]...

There are a pair of ringed antennæ projecting from the anterior end of the head, and a pair of simple eyes, placed on the dorsal surface at the roots of the antennæ.

The centrum is slightly narrower in the middle than at its two extremities. It articulates with adjacent vertebræ by a convex face in front and a concave face behind, being thus...

DEVELOPMENT OF THE BRAIN, pp. 397-407. General history. _Fore-brain._--Optic vesicles. Infundibulum. Pineal gland. Olfactory lobes. Lateral ventricles. _Mid-brain._ _Hind-brain....

Order of treatment. _External epiblast._--Characters of epiblast. Its late division into horny and epidermic layers. Comparison of with Amphibian epiblast. _The unpaired fins._...

_External epiblast._--Division into separate layers. Placoid scales. Formation of their enamel. _Lateral line._--Previous investigations. Distinctness of lateral line and latera...

Previous investigations. _Excretory organs and genital ducts in adult._ _In male._--Kidney and Wolffian body. Wolffian duct. Ureters. Cloaca. Seminal bladders. Rudimentary ovidu...

_The solid oesophagus._--OEsophagus originally hollow. Becomes solid during Stage K. _The postanal section of the alimentary tract._--Continuity of neural and alimentary canals....

_General features of the epiblast._--Original uniform constitution. Separation into lateral and central portions. _The medullary groove._--Its conversion into the medullary cana...

Division of blastoderm into two layers. Formation of segmentation cavity. Disappearance of cells from floor of segmentation cavity. Nuclei of yolk and of blastoderm. Formation o...

_The spinal nerves._--Formation of posterior roots. Later formation of anterior roots. Development of commissure uniting posterior roots. Subsequent development of posterior roo...

_The heart._--Its development. Comparison with other types. Meaning of double formation of heart. _The general circulation._ The venous system. The primitive condition of. Compa...

Appearance of impregnated germinal disc. Stage with two furrows. Stage with twenty-one segments. Structure of the sides of the furrows. Later stages of segmentation. Spindle-sha...

Structure of ripe ovum. Atrophy of germinal vesicle. The extrusion of its membrane and absorption of its contents. Oellacher's observations on the germinal vesicle. Götte's obse...