40 Comparative Studies 



in blood-serum cultures, but after growing on artificial 

 media for some months it showed only as short, plump 

 bacilli with rounded ends, the centre of which did not 

 take on stain, while the poles were deeply stained. 



All the other cultures occur as short bacilli with pointed 

 ends, sometimes having only one clear, unstained space in 

 the centre and the poles deeply stained ; again at times 

 they are made up of alternate bands of stained and un- 

 stained material. In blood-serum cultures and in alkali- 

 peptone media a considerable number of club-shaped bacilli 

 were to be seen, especially in cultures 20, 26, 27 and 29 ; 

 less markedly so in cultures 18, 21, 23, 24, 30 and 31 ; 

 while the remaining cultures only showed club-shaped 

 bacilli occasionally. A peculiarity of these cultures which 

 had been noted by other investigators, is the tendency they 

 have of two or three lying side by side in cover-slip prep- 

 arations. 



Biologically, these cultures show greater differences. A 

 most striking difference is noted in the growth on agar- 

 agar. Cultures 20, 26, 27 and 29 grow as a thick, moist, 

 glistening, white or yellowish-white layer on the surface 

 of the agar. Culture 13 grows as a thick, moist, glisten- 

 ing, yellowish layer on agar-agar. All the other cultures 

 grow as very \ninute, dry, pearly- white colonies and show 

 no tendency to coalesce, except when sown very thickly, 

 when they grow as a dull, pearly-white layer. These 

 differences in growth were somewhat less marked on blood- 

 serum, though they all manifested very much the same 

 characteristics as on agar-agar. 



In alkali-peptone bouillon (47) the same cultures show 

 characteristics which correspond with the characteristics 

 on agar-agar and on blood-serum. Cultures 20, 26, 27 and 

 29 grow with a thick yellowish-white mycoderm, which 

 sinks to the bottom of the tube after several days, while 

 cultures 18 and 21 show a very thin mycoderm. The 

 remaining cultures show a very fine flocculent deposit 



