594 DISEASE IN WILD MAMMALS AND BIRDS 
or specimens that have slight reddenings or erosions on 
the buccal mucosae suggesting possible early stages of 
streptothricosis. Five animals have now had a course of 
vaccine injections, ranging in number from 5 to 10 and in 
quantity from 0.3 to 2.4 mg. over a period of a month. 
Fourteen months have elapsed at the time of writing and 
only one case has developed, but this of course cannot 
settle the efficacy of the method ; perhaps it would be safer 
to demand that no case should ever appear in a treated 
animal, while the disease did appear in the untreated. 
The preparation of the vaccine is by no means a simple 
matter, since the surface growth upon solid media is so 
tenacious. Methods such as are employed for the 
tubercle bacillus have to be used. The first two vaccines 
were made by scraping off surface colonies from agar and 
grinding with glass balls. One successful batch was made 
recently by simply triturating the colony directly on the 
agar slant, but the latest method seems to offer the 
simplest and most generally satisfactory way. Neutral 
broth is placed in flasks containing glass beads and 
sterilized in the incubator. This is seeded with the 
Nocardia, incubated at 37° C. until the surface is covered, 
heated to 60° C. in a steam sterilizer and tested for 
sterility. If growth occur it is reheated until dead, 
whereupon the broth is syphoned off, the gro^vth emulsi- 
fied by whirling the flask, thus grinding the bacterial mass 
by the glass beads. Sufficient saline is added to make a 
workable emulsion, and the fluid then poured into bottles. 
Control by reculturing is again done, and if the fluid be 
found sterile, 0.5 per cent, trikresol is added to keep it so. 
These organisms cannot be counted accurately because 
of the variation in length, their budding and coccoid 
forms. Standardization is done by weight. A definite 
equal quantity of the suspension and of the saline used to 
make it are evaporated to dryness in weighed vessels and 
the whole then weighed. The difference is the weight of 
the organisms suspended in the saline. Such a fluid can 
