Effect of Gentian Violet. 



55 



the unstained controls, (b) Pepsin. The activity of this enzyme 

 was estimated by its action on wedges of egg albumen. It was 

 found to be unaffected by the dye. (c) Trypsin. The dye was 

 also without effect on this enzyme, (d) Rennin. The power of 

 the enzyme to clot milk was entirely uninfluenced, even by pro- 

 longed and deep staining with gentian violet, (e) Thrombin. 

 With this enzyme (kindly furnished by Prof. Howell) the results 

 though not quite so convincing as with (a), (b), (c) and (d), were 

 in general similar. Gentian violet staining does not destroy the 

 power of the enzyme to clot blood plasma, though if present in 

 large quantities the dye may hinder clotting somewhat. 



In a word the organized ferment (yeast) is "killed" by staining 

 with gentian violet; the unorganized ferments are unaffected. 



3. Toxines. The toxines of tetanus and diphtheria were 

 studied. With the former, the results were definite and constant; 

 staining of the diphtheria toxine in no way impairs its toxicity. 

 With the latter, the results were less constant; possibly some delay 

 in the death of the experimental animals is produced by previously 

 staining the tetanus toxine with gentian violet. 



4. Ultra-microscopic infections, (a) Vaccinia. Rabbits were 

 vaccinated on the back with stained and unstained vaccine. The 

 potency of the vaccinia was unimpaired by staining, for equally 

 good takes were obtained with both specimens, (b) Rabies. 

 Experiments with this agent were kindly done for me by Dr. 

 Williams at the N. Y. Board of Health Laboratory. Only a few 

 experiments were done, but the dye was apparently without effect 

 on the virus, (c) Anterior poliomyelitis. Seventeen Macacus 

 rhesus monkeys have received injections of the virus into the 

 sciatic nerve. The early experiments suggested very strongly 

 that the virus of this disease was weakened or even entirely robbed 

 of its virulence by staining with gentian violet. In one series, 

 for example, the control animal died of typical anterior polio- 

 myelitis in 7 days; the animal which received stained virus is still 

 alive and well, 8 months after injection. In the later experiments 

 inconstancy of the controls made positive deductions impossible; 

 and some of the animals which received the stained virus devel- 

 oped the disease. 



