212 M\I,ARET R. MURRAY. 



the rather large, short-winged field-cricket; and Nemobius 

 fasciatus, the small, striped ground-cricket. In practically all 

 of this work, the two crickets could be used interchangeably, 

 since the only differences between them so far as the ovarian 

 tissue is concerned, involve the size of the egg-string as a whole, 

 and the number of cells constituting an egg-follicle. 



Since, in the history of any one egg, the stages designated in 

 Fig. 15 as A, B, C, etc., form a continuous series, there is of 

 necessity considerable overlapping between the conditions de- 

 scribed for any two contiguous stages. In general, however, 

 rapid and copious secretory activity is observed in the A and B 

 follicles and to some extent also in the C follicle during September 

 and October. Mitotic figures have been observed in cells of 

 follicles distal to the C egg; only amitotic nuclear changes appear 

 in stages A, B, and C. 



III. METHOD. 



The follicle cells were studied in tissue cultures with and 

 without the use of vital stains. They were also studied after 

 treatment with six fixatives and twelve stains, with their various 

 possible combinations. 



The culture medium most successfully used is a Locke solution 

 as modified by Lewis and Robertson (M. R. Lewis and W. B. 

 Robertson, '16): 



Sea water 30 cc. 



Distilled water 50 cc. 



NaHCOj 0.02 gram 



Dextrose 0.25 gram 



To this was added o.i gram of peptone. The tissue was placed 

 in a hanging drop with a cover slip as growth support. In 

 general, the whole egg string distal to the A egg was used in one 

 implantation; the A egg was usually implanted separately. In 

 spite of precautions against septic conditions, the cultures had 

 an unusual tendency to become infected, especially with coccus 

 and bacillus forms. The greater number of the cases of infection 

 were probably due to the difficulty, at the time of implantation, 

 of keeping the ovary and the dissecting instruments from contact 

 with the contents of the digestive tract. 



