306 



CHARLES T. BRUES AND RUDOLPH W. GLASER. 



ration are of the same general shape as the cells from which they 

 originate, but much smaller, varying in length from 6.2-6.7 /x. 

 Some buds are nearly round, in which case they separate when 

 considerably smaller, about 3.7 /x in diameter. 



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FIG. i. a, Section of fat body showing symbionts in situ in overwintered 

 nymphal Pulvinaria, X 260 ; b, isolated symbionts, stained with methylene blue 

 and eosin, X 1,000. 



The internal structure of the symbionts shows very little uni- 

 formity. Sections of tissue fixed in Zenker's solution and stained 

 with methylene blue and eosin show one or several rather distinct 

 deeply stained portions that resemble nuclei. When one is pres- 

 ent it is usually central, when two or more are present, they are 

 separated rather evenly from one another and from the cell wall. 

 The remaining protoplasm shows irregular denser streaks and 

 spots of irregular size, with usually one large, several smaller, or 

 one large and one small, vacuole, with generally a number of 

 minute clear spots that can be seen only after very close examina- 

 tion. We have tried to bring out other details of structure by dif- 

 ferent methods of fixation and stajning but without much success. 

 Smears fixed by such methods as drying and submersion in abso- 

 lute alcohol and subsequent staining with Giemsa's stain, Hanson's 

 Protozoan stain and carbol-fuchsin, give quite similar pictures to 

 those in sections which are disappointing from a cytological stand- 

 point. Evidently the symbionts are of very delicate consistency. 

 No chains of symbionts occur at this time (early April) except for 

 the single attached buds, and no masses of contiguous ones are to 

 be found. 



