THE LIFE OF SARCOCYSTIS 283 



that there was a polar filament within. Such a 

 filament, if present, has probably not been seen in 

 its full length yet. 



Multiplication of the spores occurs by longi- 

 tudinal division, a feature of interest, since divi- 

 sion of spores directly into two seems uncommon 

 among these lowly organisms. All stages in this 

 division have been seen by us in 5. colii and in 

 S. tenella of the sheep. The avian form certainly 

 shows the division remarkably well. The stages of 

 growth and extension of a Sarcosporidian in the 

 vertebrate host are briefly as follows : Each spore 

 contains an amoebula which finds its way into a 

 muscle. The amoebula grows and its nucleus divides, 

 thus becoming an elongate, multinucleate mass. 

 Around each nucleus the protoplasm segregates, and 

 a number of young pansporoblasts are formed 

 (Fig. 55). At this stage pansporoblasts (sometimes 

 called sporonts) may wander out and start new 

 infections. Later, partitions or septa are formed 

 between the pansporoblasts. Several spores are 

 ultimately found in each chamber, having been formed 

 from the pansporoblast (Fig. 56). A Miescher's tube 

 is, then, a many -chambered structure containing 

 spores, the spore formation taking place more especi- 

 ally at the ends or poles of the tubes. Old Miescher's 

 tubes in section are interesting. The central part is 

 often hollow, for the spores have been imprisoned 

 there and have degenerated or disintegrated. Around 

 the hollow chambers are others containing some more 

 or less degenerate (or senile) spores. Beyond these 

 are cavities filled with well-formed Rainey's cor- 



