734 



THE AMERICAN NATURALIST [Vol. LI 



the sexual process is at the beginning of the new life cycle. 



I do not wish to veil the great discrepancy between the 

 conception of Mercier (Fig. 6) and the other authors 



Oc ^ott ^02. ^oez ^an 



mentioned. All cells are products of a copula, and there 

 is no setting apart of the pansporoblast-membrane-form- 

 ing cells or nuclei, though later they appear at the accus- 

 tomed places between the two spores (Plate I, Figs. 31, 

 32). I shall not risk an interpretation, but think a new 

 investigation on this same.subect might be very promising 

 and result in the desired uniformity. I think it highly 

 probable that in all pansporoblastic forms the spore de- 

 velopment follows the Keysselitz-Schroeder interpreta- 

 tion: that two gametocytes form the basis of the spore 

 formation. But even if one believes that the quadruple 

 group is not formed by two but by one cell pair, the prin- 

 cipal point is not changed. It is indifferent for the the- 

 oretical interpretation whether a segregation of the sec- 

 ond coll pair from tlio first takes place, and both then form 

 tlio (inndriiplo uionp, or whether two cell pairs a])proach 

 facli otlicr and forin tlic quadruple group. The papdog- 

 aiiiy is iiier(^ly a closf r one in the first case. 



To summarize : In the observed myxosporidian species 



