382 INFECTIVE DISEASES. 



smooth, or, even at this early stage, appear dry and crinkled. 

 According to the number of bacilli inoculated, the colonies will 

 either remain isolated or coalesce and form a more or less continuous 

 film. If the nutrient agar-agar has only recently been prepared, 

 there is usually a quantity of liquid present, and the bacillus forms 

 a white coating over the inoculated area and beyond it. The 

 appearances are much more characteristic when this medium is, 

 comparatively speaking, dry. A semi-transparent membranous 

 growth develops, thickens, and assumes a characteristic lichenous 

 appearance. Such a culture, examined with a pocket lens, resembles 

 a model in wax in miniature of the folds of the gastric mucous 

 membrane. In about six weeks to two months the culture has fully 

 developed. In old cultures, especially when the individual colonies 

 remain isolated, the appearance is very characteristic. Some cul- 

 tures in appearance closely resemble cultivations on blood serum. 

 The consistency of the growth depends upon the character of the 

 soil and the age of the culture. When the medium is moist the 

 growth is moist and viscous, but more often it is distinctly tallowy, 

 and in old and dry cultures scaly and friable. 



Cultivations in Glycerine Broth. — In a few days minute flakes are 

 visible, which steadily increase in size, and subside to the bottom of 

 the flask, forming in time a very copious deposit. On shaking the 

 flask, this deposit, which is extremely tenacious, rises in stringy 

 masses, and gives an appearance which is more or less character- 

 istic. If the flask is left undisturbed, a delicate veil-like film forms 

 over the surface, which can be readily broken up by gentle agitation, 

 forming flakes which gradually sink in the liquid. If undisturbed 

 for several weeks this film increases in thickness, is irregularly 

 fissured, and has more the appearance of masses of tallow floating 

 on the surface.. The growth also may be seen to extend up the side 

 of the flask above the liquid. Pasteur or Erlenmeyer flasks can be 

 employed for these cultures. Solidified egg-albumin added to the 

 glycerine broth seems to increase the amount of growth, which 

 clings to the albumin, and waves to and fro in the liquid when the 

 flask is gently shaken. The author has confirmed the observation 

 of Nocard and Roux, that sub-cultures from glycerine agar-agar, or 

 from glycerine broth, will give cultures in ordinary broth without 

 glycerine. Ordinary broth with egg-albumin, and without glycerine, 

 will also give a good growth when inoculated from previous sub- 

 cultures, although the attempt to produce primary cultures in these 

 media has hitherto failed. 



Cultivations in Glycerine- Milk, and other Media. — In milk the 



