376 ON THE NUMBER OF POLAR BODIES AND 



chromatin rods either do not divide longitudinally, or else divide 

 in this way after they have left the equatorial plate and are 

 proceeding 1 towards the poles. Carnoy does not himself attach any 

 special importance to these observations, for he only considers 

 them as proofs that the longitudinal splitting of the loops may 

 occur at various periods in different species either at the equator, 

 or on the way towards the poles, or even at the poles themselves. 

 We cannot conclude from the author's statements whether this 

 form of nuclear division only occurs in a single cell-generation 

 during spermatogenesis, as it must do if it really represents 

 a ' reducing division.' Until this point is settled, we cannot 

 decide with certainty whether the described form of karyokinesis 

 is to be considered as the 'reducing division' for which we are 

 seeking. Fresh investigations, undertaken from these points of 

 view, are necessary in order to settle the question. It would be 

 useless to seek further support for the theory by going into further 

 details, and by critically examining the numerous observations 

 upon spermatogenesis which have now been recorded. 



I will only mention that among the various nuclei and other 

 bodies in different animals which have been considered by different 

 observers as the polar bodies of the sperm-cells, or the cells which 

 form the latter in my opinion the paranucleus (' Nebenkern ') of 

 the ' spermatides ' described by La Valette St. George x has the 

 highest claim to be considered as the homologue of a polar body. 

 But I am inclined to identify it with the first rather than the 

 second polar body of the egg-cells, and to regard it as the histo- 

 genetic part of the nucleoplasm which has been expelled or 

 rendered powerless by internal transformations. There are two 

 reasons which lead me to this conclusion : first, as I have tried to 

 show above, it is probable that the ancestral germ-plasms are not 

 removed by expulsion, but by means of equal cell-division ; 

 secondly, my theory asserts that the histogenetic nucleoplasm 

 cannot be rendered powerless until the close of histological differ- 

 entiation. 



The whole question of the details of the transformations under- 

 gone by the nucleus of the male germ-cells is not ready for the 



1 La Valette St. George, ' Ueber die Genese der Samenkorper.' Fiinfte Mittheilung. 

 Die Spermatogenese bei den Saugethieren und dem Menschen,' Archiv f. mikrosk. 

 Anat. Bd. XV. 1878. 



