Jan. 15, 1920 Further Studies of Sorosporella uvella 419 



individuality to some extent; and from an examination of such free or 

 semifree individuals it is possible to determine that they are identical 

 with the free-floating, spindle-shaped cells of the blood, or in other 

 words the phagocytes. 



The phagocytes are often arranged in irregularly concentric layers 

 about a mass of free blastocysts, or in other instances infected leu- 

 cocytes seem to act as a focus around which numbers of blood cells, 

 for the most part uninfected, gather (PI. 56, A, B). Other sections 

 show what may be called compound complexes, in which there are two 

 or three foci, or centers of attraction, the whole being surrounded by a 

 common envelope composed of several layers of leucocytes. These ag- 

 gregations, or complexes, occur throughout the body cavity, though 

 more commonly perhaps near the heart or tracheae; and although they 

 are of various sizes and shapes, they tend to be roughly spherical. 



The fusion or coalescence of the amoeboid-like leucocytes recalls at 

 once the similar action of the amoebae of Myxomycetes in forming 

 Plasmodia; and furthermore, as in the Myxomycetes, this coalescence 

 is not accompanied by nuclear fusions, for the nuclei remain distinct. 



Since the phagocytic action of the blood corpuscles of susceptible 

 hosts upon the vegetative bodies of Sorosporella had been observed, 

 it was deemed advisable to determine whether or not similar action 

 would occur when the organism was introduced into the blood of non- 

 susceptible hosts. J 



In inoculation experiments it was found that when the usual methods 

 of infection were employed, silkworms {Bomhyx mori) and white grubs 

 (Lachnosterna spp.) did not succumb to the disease. Sorosporella conidia 

 were therefore injected within specimens of these insects by means 

 of a hypodermic needle. The needle was made from a piece of 4-mm. 

 glass tubing, one end of which was drawn out into a very fine point. An 

 ordinary atomizer bulb was attached to the other end. Conidia in 

 suspension in sterile water were drawn into such sterile tubes, and the 

 body of the host was punctured. Then pressure was applied to the 

 bulb, forcing the conidia into the body cavity. It was found necessary 

 to fasten the insects to some substratum in order to prevent them from 

 wriggling and rupturing the organs around the needle. The needle was 

 then quickly removed; and if the operation was carefully performed, 

 very little blood escaped. 



The technic here employed was so crude that it was impossible to 

 to measure very carefully the amount of fluid injected into the lar\^ae. 

 The diameter of the needles averaged less than i mm., and a column of 

 fluid 0.5 cm. long was considered a small dose. 



When small injections were made it was nearly always possible to 

 observe conidia in the blood of silkworms and white grubs a few hours 

 after injection, in prepared blood smears; but one or two days after in- 

 oculation it was impossible to detect fungus cells of any sort in such 



