VETEEIlSrARY MEDICINE. 771 



growth was reached in the other media." The tuhercle hacilli during the last 

 three weeks of growth were completely acid-fast. 



" One of the noteworthy changes produced in the media by the growth of 

 the organisms in the asparagin medium was the development of a mucinous- 

 like substance which was apparent even at the end of the first week. By the 

 end of the second week it had apparently reached its maximum, although it 

 persisted throughout the course of the experiment. It was possible to draw 

 out the medium in long and viscid strings by touching V with a platinum 

 needle. Although the medium underlying the pellicle of the tubercle bacillus 

 exhibited this mucinous change most strongly, the organisms themselves were 

 also somewhat mucinous in character. This viscosity was most marked in man- 

 nit, considerable in dextrose, and relatively slight in glycerin. ... It is con- 

 ceivable that the three phenomena, the decrease in weight of the tubercle 

 bacillus pellicle, the decrease in antigen content, and the decrease in vegetative 

 activity, as sliown by the ammonia curve, are parallel phenomena, and the 

 cause of the decrease in each instance is closely associated with the recession 

 of this vegetative activity." 



The metabolism of the bacilli in media with inorganic salts as sources of 

 nitrogen, was taken up in the fourth study. It was found that by growing a 

 strain of human type tubercle bacilli in " a medium of known and very simple 

 composition, consisting essentially of diammonium-hydrogen-phosphate, as a 

 combined source of nitrogen and phosphorus, and dextrose, mannit, and 

 glycerin, respectively, as sources of carbon, at the end of two weeks, 4.2 mg. of 

 nitrogen, that is to say, 10 per cent of the total nitrogen of the uninoculated 

 medium, has been so changed by the growth of this organism that it can not 

 be recovered as ammonia. This loss of ammonia is most plausibly explained on 

 the assumption that it has been built up into the bodies of the newly developed 

 bacteria. At the end of four weeks, between 40 and 50 per cent of this 'lost' 

 nitrogen has reappeared in the clear medium underlying the pellicle of the 

 tiibercle bacilli in such a form that it can again be determined as ammonia. 

 The period during which the disappearance of nitrogen from the culture fluid 

 is the greatest corresponds with the period of maximum vegetative activity in 

 the culture. Coincidently with the reappearance of this nitrogen, which can 

 be detected as ammonia in solution, there are evidences of a cessation of 

 vegetative activity. This strongly suggests that the reappearance of this am- 

 monia is associated with a certain amount of autolysis of the bodies of the 

 bacteria." 



In the fifth study, the metabolism of " lepra bacillus," grass bacillus, and 

 smegma bacillus in plain, dextrose, mannit, and glycerin broths was con- 

 sidered. It was found that " the metabolism of the smegma and grass bacilli 

 resembles that of the rapidly growing human tubercle bacilli, described pre- 

 viously, in two important particulars ; neither dextrose, mannit, nor glycerin 

 exhibits any appreciable sparing action for the protein constituents of the 

 broth, the amounts of ammonia produced being practically the same in these 

 media as in plain broth ; and their cultures present a gradual increase in 

 proteolysis to a maximum which is followed by a clearly defined recession of 

 the metabolism indicated by a gradual decrease in the ammonia content. The 

 ' lepra bacillus ' does not present this metabolic phenomenon. This would sug- 

 gest that this bacillus was entirely distinct in its cultural relationships from 

 the grass and smegma bacilli, which follow more closely the metabolism of the 

 tubercle bacillus." 



As a result of the sixth study on the occurrence of a soluble lipase in broth 

 cultures of tubercle bacilli and other acid-fast bacteria, it was determined that 

 12146°— No. 8—15 6 



