282 SOME MINUTE ANIMAL PARASITES 



tubes. If a small piece of the tube be torn open or 

 teased in a little salt solution, and then examined with 

 the microscope, hundreds of small, oval or sickle 

 shaped bodies are seen. These are the spores, for 

 which the old name was Rainey's corpuscles. If 

 sections of a Mieschers tube (Fig. 56) be examined, 

 the spores are found lying in clusters in a series of 

 chambers. Fine partitions separate one chamber from 

 another. The outer layer of the Miescher's tube may 

 show striations. 



The spores themselves vary to a great extent, both 

 in different hosts and in the same host. The Sarco- 

 cystis muris of mice has spores that are capable of 

 rapid movements ; others show but slight power 

 of progression. Spores, no matter what host they 

 belong to, are relatively fragile, and do not seem 

 well adapted for resisting external conditions of life. 

 Two types of spore have been found common in 

 Sarcocystis colii, one narrow, one broad. The narrow 

 form stains deeply, the broad one less deeply. A 

 nucleus is present, and sometimes a few deeply stain- 

 ing granules may be scattered in the spores. An 

 interesting point is that the character of the nucleus 

 changes with the age and stage of development of 

 the spore. Sometimes the nucleus has its chromatin 

 evenly distributed ; at other times it is concentrated 

 to form a compact granule or karyosome, lying 

 inside the nuclear membrane. A vesicle, which 

 may be compared with the polar capsule of the 

 Microsporidia, is often present near one end of the 

 spore, and in some cases a minute protrusion has 

 been seen from the spore in this region, suggesting 



