602 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
oedematous swelling of tlie connective tissue also results in the forma- 
tion of two cushions, one on the ovarian, the other on the vaginal side. 
Soon the placenta begins to be formed. 
Spermatogenesis of Mammals.* — Herr C. Niessing has particularly 
investigated the share which the central corpuscle and sphere have in 
forming the spermatozoon. The animals studied were hedgehog, rat, 
and mouse. The most important results are: — (1) That the centro- 
some,,with certain parts of the sphere, is taken up into the spermatozoon 
and forms an apical knot at the anterior end of the head ; (2) that 
certain other parts of the sphere are modified into the head- cap ; and 
(3) that the axial thread arises, not from the chromatoid accessory body, 
but from the nucleus. 
Spermatogenesis in Monotremes and Marsupials.! — Prof. K. von 
JBardeleben has found, in a study of the testes of Ornithorliynchm ,, 
Echidna , Dasyurus , Phalangista , &c., a confirmation of his previously 
expressed conclusion that the two main portions of the spermatozoon 
arise from two different kinds of cells. On the one hand, there is the 
spermatogonium - spermatocyte - spermatid series, dividing by karyo- 
kinesis ; on the other hand, there are the characteristic basal nuclei and 
cells, which show no hint of mitosis, but give rise to the axial filaments. 
Each filament thickens terminally and appears like a cherry on the end 
of a long stalk. After being liberated into the canal, they encounter 
spermatids, and unite with these to form spermatozoa. 
Accessory Glands of the Thyroid and Carotid.!— Prof. A. Prenant 
makes some notes on recent investigations (by Kohn, Schaper, and 
Jacoby) dealing with these structures. Jacoby found that the cranial 
part of the thymus separates off and forms the external thyroidean 
glandule ; that the carotid gland is formed in the adventitia of the 
primitive carotid ; and that the lateral lobe of the thyroid encloses an 
“ internal epithelial body,” the “ included thyroidean glandule.” 
Prenant, on the other hand, found that the third and fourth branchial 
pouches produce respectively the thymus and the lateral rudiment of 
the thyroid, and also by a thickening of their walls two glandular 
nodules, the thymoid and thyroid glandules. The former is the carotid 
gland, the other is the internal epithelial body. He adheres firmly to 
the general embryological result that the third and fourth branchial 
clefts give origin to originally similar and homologous glandular 
structures. 
Development of Allantois in Lizard.§ — Herr J. Janosik corrobo- 
rates Coming’s account of communications between the lumen of the 
allantois and the coelom. From what Strahl and others have described 
as the canal is amnio-allantoideus there is a fine cleft leading to the 
space between the epiblast and the somatopleure of the amnion, and 
thence to the coelom. This is distinctly seen in embryos of Lacertct 
agilis with 19-21 mesoblast somites, but its morphological import 
remains obscure. 
* Arch. f. Mikr. Anat., xlviii. (1896) pp. 111-42 (2 pis.), 
f Verb. Anat. Ges. X. Anat. Anzeig. Erg.-Heft, xii. (1896) pp. 38-43 (4 figs.), 
i Anat. Anzeig., xii. (1896) pp. 242-4. § Tom. cit., pp. 225-32 (4 figs.). 
