ZOOLOGY AND BOTANY, MICROSCOPY, KTC. > 167 



into which the chromatin penetrates, segregating itself and arranging 

 itself prior to division. In the nucleolar fluid there may be at the same 

 time an intense metabolism. 



. Determination of Sex.* — Heinrich Bayer discusses fertilisation and 

 sex determination from a gynaecologist's point of view. As to fertilisa- 

 tion, he agrees in the main with Boveri and de Vries. As to sex- 

 determination, he argues against the position of 0. Schultze and 

 Lenhossek, that the sex is predetermined in ovo, and inclines to attach 

 importance to the spermatozoon as well. In particular, he maintains 

 that the energy of the eperm-centrosome is determinative. "When its 

 •energy is great, the offspring tends to be female, when its energy is less, 

 the offspring tends to be male. 



Cytasters and Centrosomes in Artificial Parthenogenesis. f — E. B. 

 Wilson found that centrosomes may arise by new formation in the 

 -artificially induced parthenogenesis of sea-urchin ova. This result has 

 been vigorously criticised by Petrunkewitsch. Wilson answers the criti- 

 cisms of Petrunkewitsch, which do not seem to him to overthrow, or even 

 weaken, the case for the independent new formation of centrosomes. 



" I willingly grant that a phenomenon so surprising, and of such far- 

 reaching significance, as the new formation of centrosomes, capable of 

 division, in a non-nucleated mass of protoplasm — or the hardly less re- 

 markable one of a multiple free-formation in an entire egg of centro- 

 somes capable of subsequent division — is not to be unreservedly accepted 

 without additional study of the most careful kind, and by different 

 observers ; but if my conclusions on these points are to be rejected, it 

 must be on evidence more adequate than that brought forward by 

 Petrunkewitsch. 1 ' 



Development of the Venous System in the Mole. J — A. Soulie and 

 C. Bonne give a detailed account of the constitution and successive 

 modifications which the venous system presents during foetal life. A 

 very complete series of embryos, from 1*6 mm. to 20 mm. long, has 

 been utilised as a basis for their conclusions, which, in a synthetic and 

 •comparative manner, they give of the evolution of the venous system in 

 the mole during both the first and second circulations. 



Development of Olfactory Organ in Spinax Niger.§— 0. Sund has 

 •examined a series of embryos of S. niger up to 4 cm. He describes a 

 paired blind sac in the anterior region of the olfactory organ, which in 

 origin, development and innervation is strikingly similar to Jacobson's 

 organ, and with which the author suggests the latter is probably homo- 

 logous. 



Development of Gills of Fishes.]] — T. Moroff finds that the mode of 

 origin of the gill-slits in the different groups is as follows. In Cyclo- 

 stomes there are evaginations from the gut, which, on reaching the 



* Befruchtung und Geschlechtsbildung Strassburg (19f)4) pp. 39. See Zool 

 .Zentralbl., xi. (1904) p. 779. t Zool. Anzeig.. xxviii. (1904) pp. 8-12. 



X Journ. de l'Anat et Pbys., xli. (1905) pp. 1-39 (3 pis.)- 

 § Biol. Centralbl., xxiv. (1904) pp. 651-9. 

 H Arch. Mikr. Anut., lxiv. (1904) pp. 189-213 (2 pis.). 



