6 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Physical Equilibrium of Amphibian Ova during Maturation. * 

 E. Bataillon has experimented with eggs of frogs and toads, which, he 

 believes, exhibit variations in osmotic pressure and turgescence in the 

 course of their maturation. 



Experiments on Artificial Parthenogenesis in Vertebrata.f — 

 E. Bataillon subjected the eggs of frog and lamprey to salt solutions 

 and sugar solutions. The eggs of the frog formed, at the most, imper- 

 fect blastulae ; those of the lamprey formed complete blastulge. The 

 mitoses were mostly irregular, but some quite normal nuclear figures 

 occurred. 



Development of Chromosomes in Teleostei.t — J. Marechal has 

 studied this subject in the ovary of Trigla hirundo and Gasterosteus 

 aculeatus. Briefly reviewed, the main facts made out appear to be : 

 (1) The formation of yolk, or the trophic alterations of the growing 

 protoplasm, are temporarily related to the beginning of a finer distribu- 

 tion of the chromosomes. In general, as the protoplasm becomes 

 darker and more stainable, the chromosomes begin to appear " spiny." 

 Soon, also, several chromatic nucleoli and many chromatin granules, 

 lying chiefly on the nuclear membrane, appear. (2) In synapsis and 

 spireme phases no achromatic reticulum is to be seen between the 

 chromatic loops. When the chromosomes already show a spiny appear- 

 ance, a few delicate threads sparingly scattered stand out between them ; 

 these gradually multiply in order to form a ground reticulum, which is 

 in no way achromatic. (3) Most of the loops appear as in Selachians, 

 paired or forked. This is not so clear in Gasterosteus as in Trigla. 

 The paper contains a note on some of the stages of the ovarian eggs in 

 Amphioxus and in Ciona intestinalis. 



Ovarian Sac in Bony Fishes.§ — B. Haller has studied various 

 types of the ovary in Teleosts, and finds four conditions representing 

 phylogenetic stages. Amongst the Salmonidee, in Argentina and 

 Mallotus occurs the most primitive state, where the ovary, projecting 

 into the coelome, is band-shaped, attached by a dorsal mesentery, with 

 the formation of a lateral furrow in this band ; in others {Salmo) a 

 better passage for the eggs to the exterior is secured. This condition 

 leads over to that where the furrow is closed and each of the two 

 ovaries forms a sac. The attachment of the right side of this sac to 

 the body-wall yields a fourth modification, seen in Cyprinoids. 



Genital Glands and their Secretions.|| — G. Loisel gives a general 

 review of our knowledge of this subject, and brings forward some new 

 facts. As derived from the germinal epithelium he quotes excretory 

 pigment, the glandular tissue covering the ccelome, a portion of the 

 supra-renal, fatty bodies, Bidder's organ, lymphoid organs, and per- 

 haps the Wolffian bodies. The genital glands are the sisters of the 



* Arch. Zool. Exper., iii. (1905) Notes et Revue, ccxii.-ccxv. 



f Arch. Entwick., xviii. (1904) pp, 1-56 (4 pis., 12 figs.). 



X Anat. Anzeig., xxvi. (1905) pp. 641-52. 



§ Op. cit., xxvii. (1905) pp. 225-38. 



|| Journ. de l'Anat. et Phys., xl. (1904) pp. 536-62. 



