36 Gen. Sub. 
GENERAL SUBJECTS. 
or their chemical products, acts in a manner comparable to action of 
male element on ovum, in setting up segmentation ” 
Zacharias, 0. TJeber Eier und Samenfaden. Biol. Centralbl. vi, p. 250 ; 
Ber. 58 Yersamml. Naturf. 1885, p. 100. 
In plants and Amphibians, male cells distinguished by small or absent 
nucleoli and rich content of nuclein ; female by poverty of nuclein, 
abundance of albumen, and one or more nucleoli. The fertilized, ovum 
has thus a larger proportion of nuclein than the unfertilised. 
. Ergebnisse einer zoologischen Excursion. Z. wiss. Zool. xliii, pp. 
271-275, 4 figs. 
In describing spontaneous transverse division of Planaria, notes that 
when supply of food abundant, a new act of fission is to be observed 
before daughter bud has attainod proportions of parent, but if amount of 
food reduced or altogether withdrawn, reproduction by division com- 
pletely ceases. 
