GS 



THE AMEBIC AN NATURALIST [Vol. XLIX 



conjugation. A similar interpretation was given by 

 Calkins : 



... it is now a well-known fact that in this process of reorganization 

 the old macronueleus fragments and ultimately disappears in the cyto- 

 plasm. This disappearance must give rise to a great increase in the 

 nucleo-protein content of the cell, therefore to a new chemical composi- 

 tion of the cell as a whole. We have recently shown that, under cer- 

 tain conditions, nucleo-proteins (especially the purines) have a mark- 

 edly stimulating effect on the rate of cell division. 7 

 Now such intermingling is no more characteristic of this 

 process of asexual reorganization than it is of the reor- 

 ganization following conjugation. In both cases, as 

 Woodruff and Erdmann show, reorganization is effected 

 by the physical and chemical change of the old macro- 

 nucleus and portions of the old micronucleus or micro- 

 nuclei. The sole difference in these processes of reor- 

 ganization is not to be found in the molecular rear- 

 rangement of the cell, but, as Woodruff and Erdmann 

 state, in the presence after conjugation of a syncaryon 

 and the nuclei derived from it. This difference, how- 

 ever, does not amount to much in closely related pairs 

 in conjugation. Several observers have shown that 

 closely related individuals, even sister cells, of Para- 

 mecium may conjugate, and I have followed out through 

 360 generations the history of such an endogamous ex- 

 conjugant from a pair which came from the same ances- 

 tral cell not more than ten days prior to conjugation. 

 There can not be a great difference in the syncaryon re- 

 sulting from such a union, over the functional micronu- 

 cleus had it undergone asexual endomixis. In other 

 words, the excellent term endomixis does not indicate 

 phenomena peculiar to asexual reorganization in Para- 

 mecium, but applies equally well to the process of reor- 

 ganization following conjugation. The terms asexual en- 

 domixis and sexual endomixis may serve to dist inu-uisli 

 the process of intermingling during parthenogenesis and 

 after conjugation, respectively. 



7 "The Paedogamous Conjugation of Blepharisma undulans," Jour. 

 Morph. Vol. 23, 1912, p. 685. 



