190 Uiiiversiiij of California Publications in Zoology [Vol. 16 



ance of this classification would remove the latter group from the 

 Sporozoa altogether and place it with the Haemoflagellata. 



A careful examination of the known facts regarding the life-cycle, 

 as well as the morphology, of these two groups, reveals striking differ- 

 ences and few similarities, too few indeed to be of the taxonomic value 

 assigned to them by Hartmann. An attempt will be made in the fol- 

 lowing discussion to point these out, and also to indicate the lines along 

 which their relations may be better sought. 



I. The Binuclear Theory 



Nuclear dimorphism is not an uncommon condition in the Pro- 

 tozoa. The presence of the macro- and micronuelei have been quite 

 clearly established in many of the Ciliata, and these relations will 

 probably hold for most members of that class. The macronucleus con- 

 trols the trophic or vegetative functions and the micronucleus the 

 generative functions of the cell. At the time of conjugation the macro- 

 nucleus can be seen to degenerate 171 situ, with no trace of its material 

 passing to the gametic nuclei or to the other conjugant, thus definitely 

 showing that it takes no part in this process. 



Nowhere else among the Protozoa has nuclear dimorphism of this 

 type been thus far established. 



The attempts of Schaudinn to establish it among the Rhizopoda 

 have not been upheld by all of the facts as exhibited in his own in- 

 vestigations. He found (1903) that the gametic nuclei of the fora- 

 miniferan Polystomella crispa and the rhizopod Centropyxis aculeata 

 were formed from the chromidia scattered through the cytoplasm. A 

 certain amount of chromidia is given out by the nucleus during the 

 growth period, but before the beginning of the formation of gametes 

 the amount is greatly increased by nuclear disintegration. From 

 these chromidia a number of small nuclei are formed, after which the 

 cytoplasm breaks up into a number of small individuals. This does 

 not take place, however, until after the complete disappearance of the 

 original vegetative nucleus, or rather its change into chromidia or 

 "generative" chromatin. 



There is no evidence here of two kinds of ckromatin substance. On 

 the contrary, facts seem to point to the conclusion that the terms 

 "vegetative" and "generative" merely designate the successive states 

 or phases of the same substance, there being no indication of a loss of 

 any material in the change from a nuclear to a cytoplasmic position. 



