THE NEOSPOBIDIA 



401 



B 



stuffs by diffusion, the method by which the organism, like other 

 sporozoan parasites, obtains the required nourishment. The pseu- 

 dopodia vary in form in different species, from coarsely lobose 

 and blunt to fine filaments ending in sharp points. In some species 

 the formation of pseudopodia is localized at one pole of the body, 

 termed " anterior," and in such cases a peculiar propulsive pseudo- 

 podium (" Stemm-pseudopodium ") may be developed at the 

 posterior pole like a tail, which 

 by its elongation pushes the body 

 forward.* 



The endoplasm is distinguished 

 from the ectoplasm by its coarsely 

 granular appearance. In addition 

 to numerous nuclei and stages of 

 spore-formation, the endoplasm 

 may contain various metaplastic 

 products, such as crystals, pig- 

 ment-grains, fat-globules, etc. ; 

 but never food-vacuoles or solid 

 ingested food-particles. 



The plasmodial trophozoite 

 forms spores in its endoplasm, 

 as a rule, during the whole period 

 of growth, but may also multiply 

 by plasmotomy. In Myxidium 

 Ueberkiihm, for example, plas- 

 motomy proceeds actively during 

 the summer months, and leads 

 to the wall of the pike's bladder 

 being carpeted with the slimy, 

 orange - coloured plasmodia, the 

 presence of which can generally 

 be detected at a glance ; spore- 

 formation, on the other hand, 

 takes place almost exclusively during the colder months of the year. 



Spore-formation in the Myxosporidia is a somewhat complicated 

 process, and is accompanied by sexual phenomena, which are 

 commonly stated to be autogamous, but which are probably 

 nothing of the sort. There is a slight difference between the 

 mode of spore-formation in the Disporea, in which each 

 trophozoite produces but two spores, and the Polysporea, which 

 produce many. 



* Auerbach (758, p. 11) seems to have mistaken altogether the significance of 

 Doflein's " Stemm-pseudopodium," and applies the term to the anterior pseudo- 

 podia, which appear to be rather tactile in function in such cases. 



FIG. 165. Leptotheca agttis: young 

 plasmodial trophozoites in which 

 the spore-formation has not begun. 

 A, Individual moving forward by 

 means of the " Stemm-pseudopo- 

 dium " (st. ps.) ; B, individual in 

 which only the anterior pseudopodia 

 are developed. After Doflein. 



