732 OEDEE: MYXOSPOEIDIIDA 



Each nucleus now divides unequally, so that two small and two large 

 nuclei are present (Fig. 310). The small ones are vegetative and the 

 large ones generative nuclei. The generative nuclei become separated 

 in the cytoplasm of the parent as a large and a small cell, which may be 

 regarded as female and male gametocytes. Each of the gametocytes 

 divides to form two large female gametes and two small male gametes, 

 while the two vegetative nuclei remain unchanged. Conjugation between 

 male and female gametes takes place to form two zygotes, so that the 

 parasite again reaches a quadrinucleate stage in which its cytoplasm con- 

 tains two vegetative nuclei and two zygotes, each with a single nucleus. 

 Each zygote now proceeds to the formation of a spore. A number of 

 cells is produced, two of which give rise to the two valves of the spore, 

 two to the two polar capsules, and one to the infective amoeboid body. 

 After each zygote has formed a spore the parasite dies and degenerates, 

 the spores being liberated. Thus each parasite produces only two spores. 

 It was Myxosporidiida of this type that Doflein (1901) grouped under the 

 heading Disporea. 



Leptotheca ohlmacheri (Gurley, 1893). — This parasite was first observed 

 by Ohlmacher (1893) in the kidney tubules of Bufo lentiginosus. It was 

 studied by Whinery (1893) and Gurley (1893, 1894). The latter observer 

 named it Chloro?nyxum ohlmacheri, while Thelohan (1895) gave the name 

 Leptotheca ranee to a form in the kidneys of Rana esculenta and R. tem- 

 poraria. Labbe (1899) placed Ohlmacher's parasite in the genus Lepto- 

 theca as L. ohlmacheri, and came to the conclusion that it was identical 

 with L. rancB. The parasite has more recently been studied by Kudo 

 (19226) in R. clamitans and R. pipiens in America. 



According to Kudo, the spore contains two uninucleate amoeboid 

 bodies, and when it is placed in gastric juice or weak pepsin hydrochloric 

 acid, the amoeboid bodies show slow movements. The polar filaments 

 are extruded from the capsules, and finally the valves of the spore separate 

 (Fig. 311). By this time the two amoeboid bodies have united into a 

 single binucleate form, which escapes from the spore. It is probable that 

 the two nuclei fuse, for the earliest stages found in the kidney tubules 

 contain a single nucleus. There was no evidence of any intracellular 

 stage, the whole development appearing to take place in the lumen of the 

 tubules. It seems probable that multiplication of these forms by binary 

 fission takes place for some time, after which growth into the adult spore- 

 forming parasite occurs. 



The single nucleus divides into two nuclei of equal size, which, though 

 at first alike, soon become difi'erent in appearance, so that a vegetative 

 nucleus can be distinguished from a generative one. The latter quickly 

 divides again, so that a trinucleate parasite is produced. This contains 



