320 RESEARCH IN PROTOZOOLOGY 



lated spore) (see, for example, Kudo, 1922). Georgevitch (1919) 

 notes that the vegetative nucleus may divide once to form two 

 nuclei. In a developing sporoblast of all forms there were noted 

 two nuclei for the spore membrane, two for the sporoplasm or 

 sporoplasms, and as many nuclei as there are developing polar 

 capsules. In the case of a disporoblastic pansporoblast, the smaller 

 nucleus divides once according to the investigators who hold the 

 view 1 1 -a and forms two vegetative nuclei of the pansporoblast. 

 The large nucleus divides repeatedly, giving rise to from ten or 

 twelve to sixteen nuclei. Two spores are thus formed ; in the mean- 

 time the two vegetative nuclei degenerate with the development of 

 the spores. 



According to the investigators who hold the view ii-b-i, the 

 zygote nucleus gives rise to two "reduction nuclei" (vegetative 

 nuclei) and sixteen nuclei which develop into two bicapsular 

 spores. On the other hand, workers who hold the views ii-b-2 

 or ii-b-3, assume that the two small nuclei remain as vegeta- 

 tive nuclei of the pansporoblast and each of the other two large 

 nuclei gives rise by division to a definite number of nuclei to form 

 a spore. 



Besides these two pansporoblast nuclei, several authors note the 

 appearance of compact bodies which take nuclear stains deeply, in 

 the developing sporoblast or pansporoblast. Erdmann (1917) was 

 inclined to think them glycogen bodies which are used for the 

 formation of the spore membrane and polar filaments. Kudo ( 1923, 

 1926) observed that these bodies appear as the amount of the 

 endosome (plasmosome) of the dividing nuclei decreases and that 

 on a number of occasions the endosome appeared to be just ex- 

 truded from the nucleus through the nuclear membrane. He con- 

 sidered it probable that the endosomes of the nuclei of the develop- 

 ing sporoblasts are extruded to the periphery of the cytoplasmic 

 body and used for the formation of the spore membrane. 



13. Pathological. There is lack of precise information concern- 

 ing the pathological effect of myxosporidia upon the host body. 

 Various investigators report in numerous instances remarkable 

 changes which were supposed to be due primarily to infections of 

 certain myxosporidia, but in most cases they could not show con- 

 clusively that the changes were due exclusively to myxosporidia. 

 Observations up to 1893 are excellently described by Gurley 

 (1894), and Thelohan's monograph (1895) contains useful ob- 



