204 LABORATORY EXERCISES IN BACTERIOLOGY. 



disappearance of the color the film is dried and may be examined in oil (oil-immersion 

 lens) or covered in the usual manner before examination. Counterstaining with 

 vesuvin or eosin may be practised if desired. 



The following list includes the most important forms which are decolorized by 

 this method, while the important forms which retain the stain may be inferred from 

 their absence from the group mentioned: Gonococcus, Micrococcus of Malta fever, 

 Micrococcus catarrhalis, Micrococcus boms, Micrococcus magnus, Micrococcus Vincenzii, 

 Streptococcus Kirchneri, Streptococcus canis, Bacterium influenza, Bacterium conjunc- 

 tivitidis, Bacterium cancrosi, Bacterium agyptiacum, Bacterium chinense, Bacterium 

 Wrightii, Bacterium pneumonia (Friedlander), Bacterium cholera, Bacterium san- 

 guinarium, Bacterium avium, Bacterium saliva, Bacterium ambiguum, Bacterium 

 radiatum, Bacterium ovatum, Bacterium Lepierrei, Bacillus Marsiliensis, Bacillus coli, 

 Bacillus Wardii, Bacillus anindolicus, Bacillus enteritidis, Bacillus chologenes, Bacillus 

 toxigenus, Bacillus brassica (?), Bacillus icterogenes, Bacillus Poelsii, Bacillus colum- 

 barum, Bacillus Breslaviensis, Bacillus Salmonii, Bacillus levans, Bacillus loxiacida, 

 Bacillus morbificans, Bacillus Silberschmidii, Bacillus Murium, Bacillus intestinal is, 

 Bacillus meningitidis, Bacillus typhosus, Bacillus pseudotyphosus, Bacillus icteroides, 

 Bacillus Billingsi, Bacillus paradoxus, Bacillus pestis, Bacillus solitarius, Bacillus 

 geminus, Bacillus aquatilis-sulcatus-quartus, Bacillus primus Fullesi, Bacillus trache- 

 iphilus, Bacillus pinatus, Bacillus Ravaneli, Bacillus alcaligenes, Bacillus Friedber- 

 gensis, Bacillus solanacearum, Bacillus Weichselbaumi, Bacillus phasiani, Bacillus 

 Schafferi, Bacillus rugosus, Bacillus amsepticus, Bacillus avium, Bacillus meleagris, 

 Bacillus tetraonis, Bacillus cygneus, Bacillus aerobius, Bacillus pneumosepticus, Bacillus 

 monachce, Bacillus cuniculi, Bacillus venosus, Bacillus glischrogenus, Bacillus albus, 

 Bacillus granulatus, Bacillus stolonatus, Bacillus invisibilis, Bacillus venenosus, Bacillus 

 murinus, Bacillus denitrificans, Bacillus Stutzeri, Bacillus centra punctatus, Bacillus 

 agilis, Bacillus Hartlebii, Bacillus murisepticus, Bacillus Wesenbergii, Bacillus larvi- 

 cida, Bacillus dendriticus, Bacillus Kornii, Bacillus prodigiosus, Bacillus kiliensis, 

 Bacillus licheniformis, Bacillus oedematis, Bacillus Weigmannii, Bacillus saccharo- 

 butyricus, Bacillus longus, Pseudomonas punctata, Pseudomonas campestris, Pseudo- 

 monas pyocyanea (?), Pseudomonas capsulata, Pseudomonas fluorescens, Pseudomonas 

 putida, Microspira phosphorescens, Microspira Schuylkilliensis, Microspira comma, 

 Microspira Danubica, Microspira Beroliniensis, Microspira protea, Microspira 

 aquatilis, Spirochata Obermeieri, Mycobacterium influenza, Mycobacterium Elmassiani, 

 Mycobacterium mallei (?), Mycobacterium hastilis. 



Staining of Mycobacterium Tuberculosis and Allied Forms. The myco- 

 bacterium of tuberculosis is especially resistant to staining, and having been once 

 stained is equally resistant to decolorization by means of the mineral acids. In this 

 rests its peculiarity in differential staining. Many bacteria respond nearly or quite 

 equally to this organism when stained by Gram's method, but there are few that are 

 able to withstand the influence of the mineral acids employed for decolorization of the 

 stained preparation. The varieties which approach the tubercular organism are the 

 mycobacterium of leprosy and that of smegma, and several forms of the same group 

 isolated from butter, hay, and grass. The latter very closely simulate the organism 

 of tuberculosis ; but excluding these, the degree of resistance to decolorization by acids 

 and by alcohol serves to differentiate the others from the cause of tuberculosis. For 

 demonstration of this microbe the use of one of the aniline dyes reinforced with a 

 mordant is essential, and, with subsequent decolorization of all the elements in the 

 preparation save Mycobacterium tuberculosis by one of the mineral acids, affords a 



