448 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



macronuclear anlagen (lb, Ila, lib), a primary distinction between 

 the morphological phenomena in conjugation and in the process 

 here described is established, i.e., the important micronuclear 

 division which forms the migratory micronucleus and the sta- 

 tionary micronucleus is absent. But we wish to emphasize 

 the fact that if a third micronuclear division occurs, it can 

 equally well be a precocious division in the ascending or re- 

 construction phase of the reorganization process. 



The diagram presented herewith (text fig. 3) summarizes the 

 different cases which are possible from the observed facts. All 

 the described cases are distinguished from conjugation and autogamy 

 by the absence of the formation of a syncaryon. In the process 

 only in case la already described is it possible that a third 

 micronuclear division at the climax takes place. The difference 

 between conjugation and the process in case la consists in the 

 occurrence of one more cell division in the latter than in conju- 

 gation. The possible variations in cases lb, Ila and lib agree 

 -in the absence of the third micronuclear division under discussion. 

 Cases Ila and lib have no cell division before the formation of 

 the macronuclear anlagen, one or two so-called reduction micro- 

 nuclei remaining in the same old cell. Case lib is peculiar in 

 the shifting of one micronucleus into each new cell. 



But from a study of all the observed sequences of generations 

 ■at this period there is some evidence that case lb presents the 

 usual method of nuclear changes at this period. Line VId had 

 four and Line VIb had three animals in the reorganization process, 

 all of which were at the first stage of the ascending phase — for- 

 mation of the macronuclear anlagen. This one fact is crucial 

 evidence that a cell division has occurred before the formation of 

 the macronuclear anlagen, but no direct observation can be pre- 

 sented which determines whether the discussed micronuclear 

 division has or has not taken place, because one spindle in a 

 cell filled with chromatin bodies without a macronucleus or with 

 a macronuclear membrane devoid of chromatin can represent 

 either: (a) the discussed third micronuclear division or (b) the 

 division which forms in cases la, lb, and Ila the two new micro- 

 nuclei which in the next division form the macronuclear anlagen. 



