Jan. 15, 1920 Further Studies of Sorosporella uvella 413 



which can be seen in one preparation. Sometimes at one end, sometimes 

 at both ends of the blastocyst a budhke outgrowth or papilla appears 

 which grows rapidly until it assumes the form and approximate size of 

 its parent. For reasons given below it soon breaks away from the parent 

 cell and proceeds to form new cells by a similar process. At times a 

 mucronate outgrowth appears at the tip of the blastocyst instead of a 

 papilla, so that a short neck is formed, at the distal end of which a daughter 

 cell arises (PI. 52, I). 



Multiplication continues in this manner until enormous numbers of 

 blastocysts occur within the blood plasm ; and since they are free-floating, 

 the circulation of the blood distributes them uniformly from place to 

 place, so that they are found throughout the body cavity, within the 

 heart (PI. 55, B), and in all regions where it is possible for the blood to 

 penetrate. The nature of the blastocysts and their somewhat loose 

 attachment to one another is such that the circulation of the blood must 

 evidently be considered the essential factor in spreading them to all 

 parts of the body as well as in aiding vegetative reproduction. 



The blood lymph becomes so loaded with blastocysts that not only is 

 its progress eventually impeded but its function of supplying oxygen to 

 the organs of the insect is apparently inhibited. As a result of what is 

 perhaps lack of oxygen, the host acts as though stupefied; and, though 

 alive, it responds to stimuli feebly, remaining in a comalike condition for 

 several hours before death. 



When the insect dies or when the blood circulates slowly before death, 

 the blastocysts, though formed in the usual manner, no longer break 

 away from one another; instead of isolated cells, colonies of coherent 

 individuals are formed (PI. 51, D), which ultimately develop into the 

 resting-spore masses. At the same time that the colonies are formed, 

 however, the blastocysts individually change from an elliptical to nearly 

 spherical form. Since each blastocyst is able potentially to form new 

 colonies, a large number of the latter are produced; but many do not 

 grow to large size, evidently because the nutrient in the blood is ex- 

 hausted. Other small colonies coalesce so that large spore masses are 

 formed, and still others that are in close proximity to fat bodies or other 

 sources of nourishment are able to grow as long as this nutrient lasts. 



The writer has never seen cells of the parasite actually intruding into 

 the insect organs, and in fact the budding process of growth is such that 

 intrusion would not be expected. On the contrary there appears to be 

 a substance secreted by the fungus which causes the organs to break 

 down; and, as would be expected, those which are in contact with the 

 fungus colonies disintegrate first. 



The chitinous body wall of larvae in which resting spores are fully 

 mature is always very thin (PI. 51, K), and even the tracheae are broken 

 down completely, fragments of the taenidia only remaining; whereas 

 in insects in which blastocysts are beginning to develop the tracheae are 



