IO2 MARGARET REED LEWIS AND WM. REES B. ROBERTSON. 



trated the cells formed numerous delicate pseudopodia or flagella 

 and when the medium was too dilute the cells became swollen. 

 The solution which is most nearly isotonic is one in which the 

 cells remain round and flatten out close to the cover slip, or 

 crawl along the cover slip by means of broad, flat pseudopodia. 



The grasshopper was opened on the ventral side by means of 

 sterile scissors and the walls pinned down with sterile pins. 

 The testis follicles were then removed aseptically. Each follicle 

 of the testis is made up of a number of cysts, each of which con- 

 tains a number of cells all in the same stage of development. 

 The apical cell and the primary spermatogonia are at the blind 

 end of the follicle. The cysts which contain the secondary 

 spermatogonia, the first spermatocytes, the synapsis stages, the 

 growth stages, the first spermatocyte division stages, the second 

 spermatocytes, the second spermatocyte divisions, the spermatids, 

 and the spermatozoa are arranged in order back of this towards 

 the open end of the follicle. In order to obtain the cells in the 

 stage desired for observation, a follicle of the testis was placed 

 in a thin drop of the sterile culture medium on a sterile cover slip 

 and, with the aid of a binocular microscope, the wall of the cyst, 

 which contained the cells to be studied, was punctured with a 

 sharp, sterile needle so that the cells of the cyst flowed out into 

 the medium. The excess of the medium was drawn off by means 

 of a capillary pipette and the preparation was then sealed onto 

 a hollow ground slide by means of a vaseline ring. In case 

 stained preparations were to be observed, the vital stain, Janus 

 green or neutral red, was dissolved in the drop of the culture 

 medium in which the follicle was punctured. The cells released 

 from the cyst wall spread out in a thin layer along the cover slip 

 and were then studied by means of the No. 6 ocular and 2 mm. 

 oil immersion lens. A 4O-watt Mazda electric light was used for 

 illumination. 



Since any stage in the development of the germ cell can be 

 obtained in the above manner, it was not found necessary to 

 watch any one cell over a long period of time, although the cul- 

 tures remained healthy and dividing cells were found as late as the 

 fourth day. 



Tissue cultures of the germ cells in body fluid medium were 



