THE HjEMOSPORIDIA 371 



when full-grown attaches itself to an erythroblast and develops into the 

 leucocytozoon, losing its locomotor apparatus. The large trypanosomes in 

 question were supposed to be the sexual, propagative phases, male and 

 female, of a very minute spirochsete-like trypanosome, which represented the 

 indifferent, multiplicative form of the parasite. The existence, however, of 

 young forms of the leucocytozoon, no less than the schizogony discovered by 

 Fantham, disprove entirely any such origin from trypanosomes. 



In correspondence with his ideas upon the nature and orgin of leucocytozoa, 

 Schaudinn regarded the nucleus of the female forms (Fig. 158, B) as con- 

 sisting of a trophonucleus with a kinetonucleus (" blepharoplast ") close 

 beside it ; while the nucleus of the male leucocytozoon (Fig. 158, A) was sup- 

 posed to consist of a cluster of small trophonuclei, each with a small kineto- 

 nucleus beside it, precocious division of the two nuclei of the " male trypano- 

 some " being supposed to have produced a number of couples of nuclei in readi- 

 ness for gamete-formation. These cytological interpretations cannot be upheld. 

 There is nothing in the structure of the nucleus of the male leucocytozoon to 

 support the notion that it is not a single large nucleus, and the " blepharo- 

 plast " of the female form appears to be simply the karyosome, eccentric in 

 position. 



Schaudinn also described what he believed to be the development of 

 Leucocytozoon (or, as he named it, Spirochceta) ziemanni in Culex pipiens. 

 According to his account, the ookinete became an elongated, worm-like body 

 which divided up to produce an immense, number of spirochaetes, or very 

 slender trypanosomes. The spirochaetes were stated to find their way into the 

 Malpighian tubules, where they multiplied and occurred in vast numbers. 

 The spirochaetes, inoculated by the mosquito into the blood of the owl, there 

 became the " indifferent form of the leucocytozoon." 



The statements of Schaudinn with regard to the development of Leucocyto- 

 zoon have received no confirmation, in spite of the efforts of the Sergent 

 brothers to find experimental proof for them. These investigators were 

 unable to obtain any development of the leucocytozoon in Culex, or to 

 transmit the parasite from owl to owl by the agency of mosquitoes. They 

 found, however, that mosquitoes were commonly infected with spirochaetes 

 in the Malpighian tubules, but injection of these spirochaetes into the owl 

 produced no infection with Leucocytozoon, and there can be no doubt that 

 the spirochsetes in question were true spirochaetes, not connected in any way 

 with either trypanosomes or leucocytozoa. Mayer (685) obtained only 

 ookinetes, apparently similar to those of hakeridium, but non-pigmented 

 and slightly larger, in mosquitoes fed on owls infected with leucocytozoa, and 

 observed no sign whatever of nuclear multiplication in the ookinetes ; Wood- 

 cock's unpublished results were practically the same as those of Mayer. 

 Mat his and Le'ger (473) obtained no development of L. sabrazesi in mosquitoes, 

 bugs, and leeches, fed on well-infected fowls, nor could they bring about 

 transmission by means of mosquitoes. 



4. The Hosmogregarines. Parasites of this type have been 

 found in the blood of all classes of vertebrates, and are especially 

 common in cold-blooded animals, such as fishes and reptiles. 

 Until quite recently, haemogregarines were not known to occur in 

 birds ; but Aragao (692) has described a number of species para- 

 sitic in the leucocytes of various species of birds in Brazil. It is 

 a ciuious anomaly of the distribution of these parasites that, 

 while common in marine fishes, they are not known in fresh- 

 water fish, with the sole exception of the eel. While in other 

 classes they are parasitic in the red corpuscles, in mammals they are 

 parasitic in either the red or the white corpuscles, but more com- 



