656 SUMMARY OF CURRENT RESEARCHES RELATING TO 



■structures as parts of the excretory system, the Miillerian duct, &c, 

 which also originate from the ccelomic epithelium, but retain their 

 -epithelial character, and remain distinct from the mesenchyme. 



With regard to the spleen in the Anamnia, the author is not as yet 

 prepared to formulate conclusions, and thinks that further research is 

 necessary. He gives a useful list of the times at which the spleen 

 tippears in the Vertebrates most commonly used for embryological work. 



Mesothelial Allantoic Villi of Pig.*— Dr. C. S. Minot fiuds that in 

 young embryos of the pig the allautois gives rise to processes resembling 

 villi which grow between the organs of the abdomen, are clothed with 

 mesothelium, and when at their maximum appear like small bladders. 

 They reach their maximum development in embryos of 17 mm. in length, 

 -and in those of 20 mm. are already undergoing regressive metamor- 

 phosis. The author has not as yet found any reference in literature 

 to these structures, nor has he found them as yet elsewhere, but he has 

 not searched in any other Ungulate. In maDy other forms (man, cat, 

 dog, &c), there are slight irregularities on the surface of the mesothelium 

 in the vicinity of the umbilicus — these may represent the point of origin 

 of the villi of the pig. 



Peculiarities of Breeding and Development in Anura.f — Lilian V. 

 Sampson has brought together a useful account of unusual modes of 

 breeding and development among Anura. Thus she notes Bhacopliorus 

 ■schlegelii which kneads the jelly around the eggs into a trough ; Phyllo- 

 medusa hypochondrialis which makes a sort of leaf-nest ; Cystignathus 

 mystaceus which never goes to water even for spawning; the Surinam 

 toad ; the obstetric frog ; and many others. The value of the paper is 

 in bringing together the widely scattered observations on the subject. 



Development of Torpedo marmorata.J — Dr. J. Einmert has studied 

 embryos of this species corresponding to Balfour's stages D, F, G, and 

 H, and also embryos of Pristiurus. With regard to the origin of the 

 blood-vessels — one of the points specially studied — the author finds that 

 they originate exclusively from the mesoderm, especially the splanchno- 

 pleure. There is no indication that the endoderm takes any part in the 

 process. The aorta appears to originate from cells which migrate from 

 the dorsal end of the splanchnopleure, perhaps also from the primitive 

 segments in the space beside the notochord ; but this is uncertain. 



Oocytes of Cat.§ — Dr. Emil Holmgren has examined various kinds 

 of cells in search of the intracellular canaliculi, which he has already 

 demonstrated in nerve-cells. He has obtained interesting results in the 

 ease of ova in their growth period in new-born kittens. Such ova, on 

 staining with iron-alum-hgematoxylin and acid fuchsin-orange, show, 

 near the exeentric nucleus, a body which stains with the acid-fuchsin and 

 is usually invested by a mass of granules which take up the orange 

 stain. The body varies in shape, consists of rods or canaliculi, and 

 from its staining reactions would appear to arise from prolongations of 

 the mesenchymatous investment which surrounds the cells. These 



* Anat. Anzeig., xviii. (1900) pp. 127-3G 2 (figs.). 



t Ainer. Nat., xxxiv. (1900) pp. 6S7-715. 



% Arch. Mikr. Anat., lvi. (1900) pp. 459-90 (1 pi. and 38 figs.). 



| Anat. Anzeig., xviii. (1900) pp. 63-9 (8 figs.). 



