VETEEINARY MEDICINE. 81 



•' The dyes above mentioned are well borne for a long period if the dose of 

 the methylene blues, basic fuclisin, and crystal violet is not too large. Almost 

 any dose of the first 4 dyes mentioned is well borne. The individual bacillus 

 Itself is penetrated and well stained by all the methylene blues, by basic fuch- 

 sin, and crystal violet, by erythrosin and the eosins ; not so well by trypan 

 blue, trj-pan red, isamin blue, pyrrhol blue, pyronin, and neutral red. Methy- 

 lene blue, Bismarck brown, and brilliant cresyl blue are the only dyes which 

 have a possible bactericidal power over the organism, though many of the 

 others seem to inhibit its growth in the test tube." 



These experiments confirm von Linden's findings in so far that they demon- 

 strate the possibilities of staining the tubercle bacillus in vitro, and also Bhow 

 that the dyes penetrate the tubercles in vivo. No stained tubercle bacilli were 

 ever found in the tubercles or in tuberculous pus stained with dye. 



y. The behavior of the tubercle bacillus toward fat dyes, Hope Sherman 

 (pp. 249-273). — "All the dyes used, whether fat-soluble or not, stain pure cul- 

 tures of tubercle bacillus, en masse, because of the presence of stainable sub- 

 stances outside the bacilli. Sudan III does not stain individual tubercle bacilli, 

 either in smears of pure culture, in tuberculous pus, or in tuberculous tissue. 

 Sudan yellow and Sudan brown stain the bacilli faintly, in pure culture 

 smears, upon prolonged exposure, or on heating. Scarlet red resembles Sudan 

 III in behavior, but is slightly less inefficient, about half the tests for indi- 

 vidual staining being doubtful or even faintly positive. 



"Nile blue sulphate gives a faint and rather unsatisfactory bacillus stain, 

 as does Janus green, for the most part. A single smear stained with Janus 

 green showed deeply stained bacilli, but this could not be duplicated. Indulin 

 stains the bacilli faintly upon prolonged application. Indophenol blue does 

 not show any bacillus stain. Dimethylaminoazobenzol gives a faint and un- 

 satisfactory bacillus stain. Basic fuchsin, which is only slightly fat-soluble, 

 eosin, and methylene blue, which are not fat-soluble, stain the individual bacilli 

 deeply in a relatively short time. 



"All the dyes used stained the impure ether extract of tubercle bacilli, while 

 the purified ether extract was less readily stained by the majority of the dyes 

 not classed as ' fat dyes.' The behavior of the dyes toward the impure ether 

 extract corresponds with their behavior toward cultures of the bacilli, and is 

 very different from that toward the individual bacilli. These facts seem to 

 indicate that masses of ether-soluble substance exist on the surface of cultures 

 as well as within the bacterial protoplasm, and it is with this extracellular 

 material that the dyes combine. Basic fuchsin and eosin, and to a less extent 

 Bismarck brown resemble the regular fat dyes in the ease with which they 

 stain the ether extract. Dilute solutions of Nile blue sulphate and neutral 

 red are more efiicient than the saturated, in the staining of the ether extract. 

 The fat dyes are not serviceable for the detection of tubercle bacilli in pus 

 or in tissue, nor for their staining in pure cultures. 



"Experiments with crushed bacilli confirm Beninns' view that the acid- 

 fastness of the tubercle bacillus depends upon the physical integrity of the 

 bacterial cell. The fatty constituents of the tubercle bacillus are not, per se, 

 the cause of the stainiiig reaction characteristic of this organism." 



VI. Intra-vitam staining of tuberculous guinea pigs with fat-soluble dyes {sup- 

 plementary note), H. J. Corper (pp. 274, 275). — If indulin, dimethylaminoazoben- 

 zol (1 per cent in oil), and Bismarck brown (1 per cent in oil and water) are fed 

 to tuberculous guinea pigs, they do not appear to enter the organs nor tuber- 

 culous areas to any appreciable extent when given for a period of about 65 

 days. Alkanin and annate, 1 per cent in oil, do not enter within a period of 

 14 days. 



