EFFECTS OF AMPHIMIXIS ON THE GERM-PLASM 25 I 



somatic cells, as well as the mother-cells of both kinds of germ- 

 cells in Liliuin martagon, contain twenty-four idants, while the 

 mature germ-cells contain twelve only. We do not as yet know 

 whether this reduction is effected by a single reducing division, 

 or by two such divisions preceded by a doubling, as in the case 

 of animals. For evident theoretical reasons I consider it ex- 

 tremely unlikely that the reduction occurs in the mother-cell 

 while it is preparing for division, as Guignard thinks is the case. 

 It is very possible, however, that only one reducing division 

 takes place in this instance. 



The details of these processes in the lower plants are quite 

 unknown, probably owing to the minute size of the idants, which 

 till now has rendered the difficulties of such investigations insur- 

 mountable. It has, however, at any rate been ascertained that 

 in many marine algae (^Fncoidea) the development of the egg- 

 cells is accompanied by the formation of ' polar bodies,' which 

 certainly correspond to stunted and phyletically degenerated 

 ova : this was first shown to be the case by Butschli and Giard, 

 and the fact has long been recognised by other zoologists besides 

 myself. In the genus Fucus these polar bodies do not occur, 

 and eight eggs are formed from the primary ovum, — if I may 

 venture to apply this term to the original cell of the so-called 

 oogonium or ovary ; in an allied species of wrack, Ascop/iyllii/n 

 nodosunu only four eggs are formed from the primary ovum, but 

 four polar bodies are also produced ; in Pelvetia canaliculata 

 the primary ovum gives rise to two eggs and six polar bodies ; 



merely from a comparison of the analogous process in animals, but also 

 because I cannot help thinking that it is possible, and even probable, that 

 in this respect these otherwise admirable observations are not quite com- 

 plete. In the formation of the male germ-cells, a reducing division may 

 perhaps take place between the 'cellules mSres primordiales ' and the 

 ' cellules mdres definitives ; ' and as regards the female germ-cell, it will 

 occur in the division which gives rise to the ' cellule m6re du sac embry- 

 cnnaire.' In both cases even the most acute observer might fail to notice 

 the reducing division if his attention were not specially directed to this 

 point. Why should an arrangement for a ' reducing division ' have been 

 made in the case of animals if the reduction could take place without 

 nuclear division, and could produce the same result? Of all the other 

 numerous observations which have been made on the process of karyo- 

 kinesis, not a single one supports the view that the single (?) chromatin band 

 of the ' skein ' stage can become disintegrated into half as many idants as 

 were previously present in the nucleus. 



