PROTOZOA IN CARCINOMA. 189 



host, the protoplasmic contents contract, and form a sphere lying 

 free within the cyst wall. Under suitable circumstances this ball 

 of protoplasm pushes out projections, at first flattened, but soon 

 becoming more distinct, till at length it divides into four distinct 

 smaller spherules. Each of these protoplasmic masses becomes 

 somewhat elongated, and forms, within itself, two crescentic germs 

 lying in its long axis, leaving unutilised a small nuclear mass. A 

 wall of less density than the outer cyst is formed round each of 

 these groups of two germs, and then this stage of development 

 is complete. 



In this condition the parasite seems very resistant to injurious 

 influences, and is capable of remaining alive for at least 6 months. 



Methods. 



For the purpose of noting the changes which I have briefly 

 mentioned, the parasites obtained from recently killed animals may 

 be placed on a cover glass, and examined as a drop cultivation. 

 The method which I have found most useful is that recommended 

 by Professor Delepine, under the name of inter-lamellar films.* 

 In this way the cycle of development, which I have described, 

 will be accomplished in less than a week, the transformation into 

 four daughter cells being noticeable on the third day, at the ordin- 

 ary temperature of a room. 



On commencing these observations, the ordinary bacteriological 

 processes were made use of, with very little result. Tubes of ster- 

 ilised blood serum, bouillon, and other media, were utilised, and 

 the usual precautions observed. Subsequently the inoculated 

 materials were placed in incubators at temperatures of 2o^C. and 

 38 '^C. The more elaborate the precautions, however, the less 

 result was obtained. The organism flourished best when freely 

 exposed to the atmosphere. And as R. Pfeiffer observes, the 

 presence of carbonic acid, and the change from the temperature 

 of the body to the cooler external temperature, aid in their devel- 

 opment. A warm temperature, and want of free aeration, modify 

 and even prevent the changes described, and influences of this 

 sort no doubt account for the very great discrepancies, as to time, 



* SeQ /ourn. Micros., Third Series, Vol. i., p. 339, 1891. 



