518 SUMMARY OF CURRENT RESEARCHES RELATING TO 
influences, are known to hasten the development of silkworm eggs. The 
removal of the varnishing secretion facilitates gaseous interchange, and 
increases the vitality. 
More striking, however, is the fact that unfertilised eggs are stimu- 
lated to parthenogenetic development by gentle friction, Parthenogenetic 
development does indeed occur apart from this, and is most frequent in 
the eggs of robust females. 
Wind-Eggs.* — M. Xavier Raspail describes a “ wind-egg ” or “ cock’s 
egg ” which he found in the nest of Cannabina linota. He has in his 
long experience found only four of these peculiar eggs in the nests of 
wild birds. Various hypotheses have been suggested to explain them. 
That they are cock’s eggs is absurd ; that they are laid by immature or 
exhausted females is contradicted by the case described. Raspail’s con- 
clusion is that they are not really eggs at all. Some stimulus provokes 
the secretion of albumen in the upper part of the oviduct; the mass 
acquires ovoid form as it passes downwards ; and a shell is formed 
around it. 
Fourth Visceral Cleft and lateral Thyroid in Cat.f — P. Verdun 
finds that the median thyroid arises as an epithelial bud from the anterior 
wall of the bucco-pharyngeal cavity near the level of the second branchial 
arches. All the secretory parenchyma, as in rabbit and mole, comes 
from this median rudiment. The lateral thyroids are paired organs, 
which seem to arise on each side of the ventral wall of the fourth 
visceral pouch. The tliyroidean glands arise as hemispherical thicken- 
ings of the dorsal and external wall of the same pouches. 
Development of Hedgehog’s Spines.f — Dr. Hs. Sprenger gives a 
detailed account of the structure and development of the hedgehog’s 
spines. Like hairs, they show three areas, — a medulla, a cortex, and a 
cuticula ; and their development in the embryo is at first essentially the 
same as that of hairs. 
Organ in Embryo Reptiles like a Hypochorda.§— Prof. A. Prenant 
finds that in embryos of Anguis fragilis , Lacerta viridis, L. agilis , Agama 
Bibronii , and Tropidonotus natrix, there is a median dorsal pharyngeal 
plate, which seems comparable to, if not strictly homologous with, the 
hypochorda of Ichthyopsida. 
Gastrula and Archenteron of Salamander. j| — Dr. Hj. Gronroos 
concludes that the primitive alimentary cavity in Salamandra maculosa 
is formed from two components, — (a) in small part, from the gastrula- 
invagination, and (b) for the most part, from an independent cavity 
arising internally as a modification of the segmentation cavity. 
Chondrocranium in Ichthyopsida.1T — Mr. G.M. Winslow has studied 
this in Ambly stoma and other Urodela, in Pipa, in Ichthyophis, and in 
Polypterus , Protopterus , and trout. He gives excellent figures of the 
models which he constructed by Born’s method. One of his aims was to 
* Bull. Soc. Zool. France, xxiii. (1898) pp. 94-7. 
f Journ. Anat. Physiol., xxxiv. (1898) pp. 265-304 (1 pi. and 12 figs ). 
t Zool. Jahrb., xi. pp. 97-152 (3 pis.). 
§ Journ. Anat. Physiol., xxxiv. (1898) pp. 433-62 (3 pis.). 
|| Anat. Anzeig., xiv. (1898) pp. 456-63 (6 figs.), 
f Tufts College Studies, No. 5, 1898, pp. 147-201 (4 pis.). 
