ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
567 
Remarkable Abnormality in Development of Hen’s Egg.* — M. 
Etienne Rabaud describes the formation of blastoderms without further 
embryonic development. After four and eight days’ incubation only 
blastoderms were formed. The endoderm had an entirely parablastic 
appearance, the mesoderm was simply a somatopleure, there was an 
excessive development of blood-vessels, and there was no notochord. 
The observer finds in the abnormalities support for three conclusions, — 
( 0 ) that the endoderm is parablastic in origin ; (6) that the vascular 
system has an endoderrao* parablastic origin ; and (c) that the notochord 
arises from the vitelline, not from the invaginated or gastrula endoderm. 
Bole of the Periblast in Teleosts/f — Prof. W. Reinhard found in 
a Teleost embryo with closed Kupffer’s vesicle and completed ento- 
blast, that there were two masses of large cells with large nuclei lying 
on each side of the embryo about the middle of its length. They 
resembled those cells which penetrate into Kuptfer’s vesicle and form 
the beginning of the entoblast. They differentiate into the periblast, 
and lie beneath the lateral plates ; and they insinuate themselves into 
the splanchnopleure and somatopleure. It is probable that they serve 
mainly to form the blood. 
Protoplasmic Phenomena in the Trout Ovum.J — Prof. W. His 
describes the fresh protoplasm as a viscid fluid easily drawn out into 
threads, and distinguishes a turbid granular morphoplasm from a trans- 
parent hyaloplasm. The further development advances, the more does 
the hyaloplasm increase and the granular plasm decrease. 
The blastomeres show persistent amoeboid movements ; moreover, 
if an egg be opened during the later stages of segmentation, almost 
all the cells protrude finger-like processes, and after a short time retract 
them. 
The morphoplasm of the blastomeres forms a fine framework studded 
with plasmosomes : internally it surrounds the nucleus, externally it 
shows a membranous limiting zone ; the meshes are occupied by hyalo- 
plasm. The great and rapid changes which may occur in the form and 
arrangement of the morphoplasmic framework suggest the probability 
that its connecting medium does not mix with the hyaloplasm. The 
latter is indifferent to the fixatives which precipitate albuminoids. 
When the egg passes into water there is a concentration of the plasma 
into an almost uniform — isotypic— lounded elevation. As segmentation 
sets in, the isotypic character is lost. 
The membranous boundaries of the blastomeres arise from a thicken- 
ing and fusion of morphoplasmic strands. Nothing is known of the 
internal organisation of the hyaloplasm, and it may be that its functional 
role is secondary to that of the morphoplasm. 
As the functional state changes, e.g. in amoeboid movements or in 
divisions, the distribution of the morphoplasm and hyaloplasm changes. 
The hyaline protuberances of the amoeboid cells are still surrounded by a 
membranous limiting layer, and are traversed by a very fine and sparse 
plasmic framework. The latter becomes denser, and the hyaline pro- 
* Comptes Rend us, cxxix. (1899) pp. 167-8. 
f Biol. Centra lbl., xix. (1899) pp. 480-7. 
t Abh. k. S'aelis. Ges. Wiss. Leipzig, xxv. (1899) pp. 159-218 (3 pis. and 21 figs.). 
