478 Miscellaneous. 
form of a tube. This tube persists until the later stages of deve- 
lopment, and grows in length with the whole cervical region 
without increasing in circumference, so that it finally constitutes a 
long, thin, caudally directed, cervical, fistulous canal. In young 
developmental stages of snakes and lizards we certainly meet with 
a similar canal in a rudimentary condition; in these forms, how- 
ever, it undergoes no further development, but disappears much 
earlier. 
7. The third branchial pouch swells out into an epithelial follicle, 
with many secondary evaginations. This becomes constricted off 
from the branchial gut, and the evaginations transform themselves 
into thymus-tissue, in the interior of which, however, the central 
epithelial follicle persists. The latter may be regarded as the 
homologue of the carotid body in the lizards. 
8. The fourth and fifth branchial pouches develop jointly with 
the above-mentioned supra-pericardial evaginations from a lateral 
ceecum-shaped fold at the posterior end of the branchial gut 
(recessus preecervicalis), similarly to what is found to be the case in 
snakes. They soon become entirely constricted off from the 
branchial gut, and in this manner form a complex of three epithelial 
vesicles in connexion one with the other. Now, if their further 
development also takes place on the same lines as in the snakes, the 
two foremost of these vesicles, which represent the remnants of the 
fourth and fifth branchial pouches, should develop into thymus-tissue, 
while the third and hindermost should, on the contrary, remain in an 
epithelial condition. This, however, is not the case: all three 
retain an epithelial character, and are met with in this shape, even 
in much later developmental stages, between the aortic and pulmo- 
nary arches. ‘They do not come into connexion with the thyroid. 
9. The aorta develops from the artery of the fourth branchial 
arch, the pulmonary artery from that of the sixth. The fifth aortic 
arch, the rudiment of which arises between the fourth and fifth 
branchial pouches, very soon becomes aborted again, as I have also 
shown to be the case in snakes and lizards. 
10. The observations here detailed confirm the theories as to the 
probable origin of the thymus and of the epithelial rudiments in 
the cervical region, which I arrived at in the anatomical investiga- 
tion of young turtles, and to which I have already drawn attention 
in a previous memoir (“ Beitriige zur Kenntnis der Halsgegend bei 
Reptilien: I. Anatomischer Teil,” published in ‘ Bijdragen tot de 
Dierkunde, uitgegeven door het Genootschap Natura Artis Magistra 
te Amsterdam,’ 1880).— Anatomischer Anzeiger, vill. Jahrg., nos. 23 
and 24, October 10, 1893, pp. 801-803. 
Observations on the Karyokinetic Phenomena in the Cells of the 
Blastoderm of Teleosteans. By MM. E. Batartion and R. Ka@unmr. 
In a previous communication we have described the results of our 
researches upon the extension of the blastoderm on the surface of 
