138 The Microscope. 



again with pure turpentine, then placed in 96° alcohol, then in 

 dilute alcohol, then in very dilute alcohol and finally in water ; the 

 sections can then be stained in the usual manner, washed, dehy- 

 di'ated and mounted as before. 



In conclusion, I should like again to say that there is scarcely 

 anything in this paper which is original. The details have been 

 selected from various sources, and a few slight modifications added. 



Harvard Medical School. 



MORPHO-BIOLOGICAL CHAKACTERISTICS OF THE GERM 

 OF THE SOUTHERN CATTLE PLAGUE. 



FRANK K. BILLINGS. 



{Continued.) 



TN general they appear either single or in pairs. In very old cul- 

 -^ tures these micro-organisms become thinner, more rod-like, and 

 color more diffusely with the same degree of exposure to the tinction, 

 and the whole substance is either not visible at all, or veiy faint. 

 (Fig. 3.*) Again, such old cultures are very replete in apparent 

 micrococci of various dimensions, which might lead one into the 

 eiTor of thinking that his cultures had become polluted. I call this 

 last condition that of coccoid degeneration. (Fig. 3.) Or, we may 

 see unusually long objects, the longitudinal diameter being twice or 

 three times that of the mature organism, and the white or uncolored 

 substance occupying a corresponding extensive amount of space, 

 while the dark or colored ends may be somewhat larger or of the 

 same size as those of the mature object. This condition represents 

 the first step in the developmerit of these organisms, that is, they 

 become longer, and more of this white substance is secreted. (Fig. 4.) 

 The next step in the process of vegetative development is the sepa- 

 ration of one of the pole or coccoid ends, which then becomes free, 

 and for a moment is exactly round like a coccus; and, as in a hang- 

 ing-drop culture (to which I always add a very slight amount of 

 an aqueous coloring solution), one will naturally see a very large 

 number of these coccoid objects, on account of the fact that each 

 individual present is continually going through the same process of 

 multiplication. Here, again, one may see a condition or phenome- 

 non that might be misleading. One of the coccoid ends having been 

 separated, the other may still remain connected with the white 



*See April Microscope. 



