462 PROCEEDINGS OF THE ACADEMY OF [July, 



well-known rule that chromatin does not break clown so quickly as 

 cytoplasm. 



In general, the line of demarcation between the normal and degen- 

 erate spores was abrupt. The same compartment might be filled 

 partly with normal spores and partly with debris. 



The degenerating spores differ from the normal spores in being- 

 shorter and broader, even at times round. As the spore changes in 

 shape, the cytoplasm becomes very loose and to a large extent loses 

 its ability to stain, the spores frequently taking on the form of a 

 chromatin mass lying in an empty shell. It is on account of these 

 observations on the sectioned cyst that the short, broad spores found 

 in the fresh preparations are believed to be degenerate. 



The relative extent of central core and peripheral layer in the make 

 up of the cyst is merely a question of its age. Thus, Stiles found the 

 small, intramuscular cysts to be without a central core. Further, 

 in his description of the intermuscular form, Stiles gives .48 mm. for 

 the thickness, and in his figures the central core is relatively very 

 much smaller than it is in my material, where the diameter is as much 

 as 1 millimeter. It is merely a matter of evolution. The cysts herein 

 described are older than those studied by Stiles and spore degeneration 

 has proceeded much further. 



Smears. — The description which follows is based wholly on material 

 fixed in osmic acid vapor and absolute alcohol, the other fixations 

 giving obviously bad results. The three different stains mentioned 

 above were all used, and all were good. They gave, however, quite 

 different appearances, which will be noted as the description proceeds. 

 Yet although the appearances were quite different, it was perfectly 

 easy to correlate them. No one of the three stains showed any struc- 

 tural details not shown by the other two. The distinction between 

 them had to do primarily with the chemical composition of the different 

 parts of the spore. 



As was to be expected, the sharpest pictures were obtained with 

 iron hematoxylin and acid fuchsin. This method was best for the 

 detection of the presence and form of the figured elements. But 

 iron hsematoxylin does not distinguish between different grades of 

 chromatin, staining that containing much nucleic acid the same as 

 that which contains little. Differences of this sort were, however, 

 brought out by thionin and Wright's stain. 



The observations were made with a 2 mm. apochromatic oil immer- 

 sion lens, with a No. 12 or No. 18 eye-piece. These give, respectively, 

 1,500 and 2,250 diameters. The light was obtained from an incan- 



