RESEARCHES ON KARYOKINESIS AND CELL DIVISION. 47 



of the spermatospore to form several spermatozoa. The 

 tlifierence between the two processes could be explained by 

 the fact that the ovum requires for its development a large 

 supply of food material. One of the daughter ova has been 

 selected to develop, and possesses all the food material, 

 while the others remain small and incapable of forming an 

 embryo. On the other hand, fertilization is more certainly 

 ensured by a number of small spermatozoa than by a few of 

 larger size, and thus the division of the mother cell of the 

 male element is a process of functional importance, while in 

 the female it has become rudimentary. 



Do Cells Divide without Karyokinesis ? — Since the process 

 of karyokinesis occurs in such diverse parts of both the 

 animal and vegetable kingdoms, there is ground for in- 

 quiring whether it is universal. Flemming doubts whether 

 cell multiplication by any other method has yet been 

 definitely proved. Klein, in a recent number of this 

 Journal (July, 18T9), attempted to prove from the ob- 

 served ratios of karyokinetic figures to resting nuclei in 

 preparations from the epithelium of the newt, that the 

 number of indirect divisions was insufficient to account for 

 the rapid regeneration of that epithelium. To this Flemming 

 replies by calculating from the same data and proving that 

 the ratios are sufficient. Van Beneden believed that multi- 

 nuclear cells arise by direct division of the nucleus of a 

 uninucleate cell, but the indirect division of a nucleus has 

 been often observed to take place without any division of 

 the cell containing it. Multinuclear cells are frequently 

 found with all their nuclei in process of indirect division ; 

 they are generally all in the same phase though not in- 

 variably. The division of Amoebae and amo3boid cells seems 

 to be unaccompanied by karyokinetic changes, but the 

 nuclei of these are very small and difficult to observe. 

 F. Schmitz^ has described a direct division in vegetable 

 cells without karyokinetic changes. 



Flemming found karyokinetic figures in colourless cells in 

 the blood of a man suffering from leucocythsemia, but these 

 were not sufficiently common to account for the whole number 

 of such cells, and he thinks it doubtful whether the numerous 

 colourless cells of the blood in leucocythsemia are the same 

 as the colourless blood cells of normal blood ; they are more 

 probably young stages of red cells derived from the spleen 

 and bone-marrow. On the other hand, Franz Schultze^ was 

 fortunate enough to observe a living specimen of Amoaba 



' S. B. Niederrhein, Ges. Naturwiss. u. Heilkun. Bonn, 1880. 

 ^ ' Archiv, ' Mik. Anat./ Bd. 11, 1875. 



