VETERINAKY MEDICINE. 287 



process of disintegration. He believes that were the acid wholly of post-mortem 

 origin its neutralization could hardly be expected to revive a portion of the 

 bacilli to renewed activitj'. 



Some further tests which were made with media containing various amounts 

 of glycerin showed that two processes may occur, one being a rapid fermentation 

 and the other a later disintegration process. The author was able to confirm a 

 jtrevious conclusion that where only small amounts of glycerin (1 per cent in 

 bouillon) are present the tubercle bacillus produces an alkalin reaction. When 

 a slight acid reaction in 1 per cent glycerin bouillon is present, this is due to a 

 disintegration process. " The difference in the reaction of 1 and 4 per cent 

 glycerin bouillon in the human type after three months is probably due to 

 acid production in glycerin not used up in the growth of bacilli. Under the 

 conditions and with the amount of peptone, etc., supplied it is evident fmm 

 the results that from 1.5 to 2 per cent glycerin represents the average amount 

 utilizable. With increased amounts of peptone, etc., and the neutralization of 

 the acids formed, more glycerin may perhaps be consumed." 



In order to determine the correctness of GrifKth's statement that the degree 

 of acidity produced is a function of the amount of growth rather than being 

 specific of a type, the author performed some tests, the results of which show 

 that where acids are produced the bulk of growth does not seem to increase 

 beyond a certain limit, this being dependent upon the amount of glycerin 

 present, and probably because the acids inhibit. The diagrams also " prove 

 that 2 per cent glycerin in bouillon is not sufficient to bring out the differences 

 between the bovine and the human type in all strains." 



An experiment to determine the behavior of the bovine and human type of 

 bacilli in the presence of dextrose showed that in a flask containing acid 

 bouillon without either dextrose or glycerin only a slight multiplication of the 

 bacilli took place. Flasks containing dextrose remained practically neutral. 

 The author does not believe dextrose a good substitute for glycerin. All claims 

 of transformation by passages of the human into the bovine type or vice versa 

 must, according to him, pass the test of the reaction curve as well as the others 

 before such transformations can be accepted as accomplished facts. 



The relative importance of the bovine and human types of tubercle bacilli 

 in the different forms of human tuberculosis, W. H. Park and C. Krumwiede, 

 Jr. {Jour. Med. Research, 23 {1910), .A'o. 2, pp. 205-368; CcntU. Bakt. [etc.'], 1. 

 AM., Rcf., Jtl {1910), No. 22-24, PP- 673-680).— These investigations were con- 

 ducted for the purpose of determining the relative importance of human and 

 bovine types of bacilli in the prevalence of tuberculosis in man. The cases 

 selected were taken without regard to the age of the patient or the type of the 

 disease. The bacterial cultures employed were in every instance isolated 

 through the guinea pig and egg media were used to cultivate the various strains 

 obtained. 



When using Lubenau's medium (glycerinated egg) the bovine type of bacillus 

 could only be sparsely propagated or not at all, while the human type flour- 

 ished. The authors believe this to be a good differential method. 



To control the difference between the plain egg and the glycerinated egg 

 media the investigators made use of a glycerin-potato medium free from co- 

 agulable protein. It was noted that when adding glycerin bouillon to the egg 

 media for growing the bacilli from the egg to the bouillon, the virus of the 

 bovine type failed to form a pellicle in the first few generations, whereas on 

 the other hand, the human type formed a pellicle at the outset without any 

 trouble. Slightly perceptible differences alone could be noted in the morphology 

 of the bacilli, and only when they were cultivated through some generations. 

 101861°— No. 3—11 7 



