468 PROCEEDINGS OF THE ACADEMY OF [Juty, 



This does not prove that the spores were no longer living, as it is 

 by no means easy to get Sarcosporidia spores to display movements. 

 Some years ago, at the Pathological Laboratory of the Medical School 

 of the University of Pennsylvania, some experiments were made 

 with the spores of Sarcocystis muris. It was found that if these were 

 kept in the incubator, in some appropriate medium, and then examined 

 at a temperature of 32° C, very lively movements were displayed. 

 These movements, however, were not maintained for any length of 

 time, even at this temperature, and at ordinary room temperature 

 quickly ceased. It is evident that the organisms are sensitive to any 

 fall of temperature below the so-called blood heat. 



Methods. 



Both fresh and prepared material were studied. The latter was 

 either smears or paraffin sections. The smears were prepared as 

 follows: A cyst was removed from the muscle, placed on a slide 

 with a small drop of salt solution, and broken into several pieces 

 with needles. These pieces were then smeared over the slide, thus 

 scattering the spores, and the preparation fixed before it had dried. 

 Three methods were used, the best results being obtained with fixa- 

 tion in vapor of osmic acid. For this a wide-mouthed, glass-stoppered 

 bottle was used, in which was placed a small quantity of a 4 per cent, 

 solution of osmic acid. The wet smear was left in this bottle ten to 

 thirty seconds, sometimes more, and then transferred at once to 

 absolute alcohol. The air in such a bottle is saturated not only with 

 osmic acid vapor, but with water vapor as well and the smears do not 

 dry. It may be noted that any osmic acid solution which adheres 

 to the slide after removal from the fixing bottle must be wiped off 

 before immersion in alcohol. 



Other smears were fixed by dropping on them, while still wet, a 

 quantity of fixative. Two of these were used: Hermann's fluid and 

 an alcoholic corrosive acetic mixture made up as follows: 



95% alcohol 50 parts. 



Sat. sol. of HgCb in water 50 parts. 



Glacial acetic acid 5 parts. 



Both of these fluids caused the parasite to swell and to become 

 relatively very much broader than it was in the fresh state. Nor 

 were the structural details preserved anything like so well as with 

 fixation in osmic acid vapor. 



Three stains were used : 



1. Iron hematoxylin and acid fuchsin. 



