196 THE ANIMAL PARASITES OF MAN 



neighbourhoods of Calcutta and Madras, and the parasite has been 

 seen in Ceylon. Similar structures have since been described from 

 the United States and South America. 



The Rhinosporidium polypus is said not to be particularly painful, 

 though nasal forms must interfere with breathing to some extent. The 

 first nasal polyp reported from India formed a vascular pedunculated 

 growth on the septum nasi and was about the size of a large pea or 

 raspberry. It was compared with a raspberry, being red in colour 

 with a number of small whitish dots upon its surface. When the 

 tumour was cut, a number of similar whitish dots were seen within. 

 These were the cysts of Rhinosporidium. According to Minchin 

 and Fantham 1 (1905), they vary considerably in size and measure up 

 to 200 //, or 250 IJL in diameter. Each possesses a cyst wall which varies 

 in thickness in different cysts. Its outer wall is always firm and 

 distinct, the inner limit being less definite at times. Each large cyst 

 is filled with numbers of spherical or oval bodies, showing every 

 gradation between small ones at the periphery and large ones at the 

 centre (fig. 112). Roughly, three zones of parasites can be dis- 

 tinguished in a large cyst, a peripheral set consisting of the youngest 

 parasites, an intermediate group and a central, oldest zone. A large 

 cyst may possess a pore for the egress of its contents. Some of the 

 cysts show polar distribution of the zones. 



The youngest forms of Rhinosporidium are difficult to detect. 

 They are small, granular masses, round, ovoid or irregular and at times 

 even amoeboid in appearance. These are young trophozoites. They 

 increase in size, but encystment occurs early, the outer layer becoming 

 firm so that the organisms have a definite contour. Each is soon 

 multinucleate and the cytoplasm segments around the nuclei. The 

 cyst thus becomes full of uninucleate pansporoblasts or sporonts, 

 with a peripheral layer of undifferentiated protoplasm. The pan- 

 sporoblasts grow in size. In the larger cysts the formation of 

 pansporoblasts progresses at the expense of the peripheral layer of 

 protoplasm, which, ho\vever, continues to grow, so that the cyst as 

 a whole increases in size. The pansporoblasts at first are uninucleate 

 (fig. 112, a), and then undergo nuclear multiplication. This is well seen 

 in the intermediate zone of parasites, where the pansporoblasts show 

 first one, then two, then four or more spores (fig. 112, 6), while in the 

 oldest centrally placed pansporoblasts, about a dozen or sixteen 

 closely packed spores (fig. 112, c), can be seen. The spore is small 

 and rounded, and its nucleus is clear and distinct. The fully formed 

 pansporoblast or spore morula becomes surrounded by a membrane. 



Certain of the cysts have been found in a ruptured condition,. 



1 Quart. Journ. Microsc. Set., xlix, p. 521. 



