April 1892.] THE BOTANICAL SOCIETY OF EDINBURGH. 417 



of the oosphere (or gamete), which was hitherto wanting to 

 it, and which it needs for further development, -and suggests 

 that this " something " may be a ferment. 



Weismann does not believe that there is any fundamental 

 distinction between the two sexes, or between the nuclei of 

 the reproductive elements which represent them in their 

 most condensed form, as has already been pointed out. He 

 further maintains that the normal egg in the higher animals 

 gets rid of its oxogenetic plasma by the formation of the first 

 polar body, and then removes one-half of its germplasma 

 (and with this one-half of its hereditary tendencies) by the 

 formation of the second polar body. This removal of the 

 female germplasma necessitates the acquirement of some 

 new germplasma, which latter is brought to the egg by the 

 spermatozoon. 



Fertilisation then consists in the acquirement of a certain 

 amount of germplasma (and with it of a certain number of 

 new hereditary tendencies), which doubles the amount of the 

 germplasma in the egg, and thus leads to a segmentation of 

 the ovum. Hence the segmentation of the egg depends simply 

 on mere c[uantity of germplasma. 



As Weismann's view\s are purely teleological and inspired 

 by a desire to explain heredity, it is only natural that the 

 author should have arrived at the very ingenious, but 

 decidedly wrong, notion about the " functions " of the polar 

 bodies, and that he should liave considered his germplasma 

 to be so isolated a substance in the body, uninfiuenced by 

 any environmental conditions that may act on the soma of 

 the parent. 



Strasburger maintains that sexual cells contain proportion- 

 ally a smaller amount of nucleo-idioplasm than the asexual cells, 

 and that for this reason they are not capable of undergoing 

 further division. Therefore, between asexual and sexual cells, 

 no qualitative, but only a quantitative, difference exists, due 

 to the varying amount of nucleo-idioplasm. Fertilisation, 

 according to this view, is equivalent to an increase of the 

 mass of nucleo-idioplasm in the ovum, an increase which 

 leads to the division of the egg. 



Strasburger and Weismann then agree to fertilisation being 

 brought about by a doubling of the chromatin-elements 

 of the female samete-nucleus. 



