206 Uiiirfrsitii of California Publiralious in Zoology [Vol. lii 



of the haemoflagellates. These claims recognize a polyphyletic origin 

 for the present class of Sporozoa, and give to the Haemosporidia a 

 flagellate ancestry, which is as yet capable of no proof. This assump- 

 tion has resulted in the attempt to find in the morphology and life- 

 history of these forms flagellate stages and organelles. 



From the facts presented here as well as from the figures cited, 

 it is evident that the constant presence of a permanent cell organ in 

 the Haemosporidia comparable to the parabasal body of the trypano- 

 somes has not thus far been demonstrated, neither have undoubted 

 flagellate stages in their life-history been shown to occur in a single 

 authentic instance. "With no recognizable data by which to relate 

 them to the flagellates, and lacking a structure comparable to the 

 parabasal body, this group cannot logically be placed among the 

 "Binucleata." 



With this review of the order Binucleata an estimate has been 

 given of the validity of the claims for affinities between two widely 

 diverse groups, and the grounds for the binuclear theory upon which 

 these claims are based. It has been shown that these claims rest upon 

 an insecure foundation of facts which are susceptible of other inter- 

 pretations. Some of these interpretations have already been pointed 

 out and in the following pages will be expanded more fully. 



In the evidence thus presented, emphasis has been laid on those 

 points in the structure of both the Haeflagellata and Haemosporidia 

 which have been used by the authors of the Binucleata as constituting 

 the basis of their claims for a binuclear condition in these forms, as 

 well as for flagellate affinities of the Haemosporidia. 



D. THE PARABASAL BODY AS A SPECIALIZED STRUCTURE 



I. Phylogenetic Development 



The characteristic motor apparatus of the Mastigophora, as well 

 as of the flagellated stages of other organisms, consists of one or more 

 flagella attached either to the nucleus, or to a single granule or granule 

 complex, the blepharoplast, which may or may not be connected with 

 the nucleus. This type of organization is found generally throughout 

 the free-living flagellates as well as in the parasitic forms and is evi- 

 dently the primary condition. 



The terminology for the neuromotor apparatus of the flagellates, 



