47 



125 



garicum, have each its own manner of agglutination^). We "were unfortunately debarred 

 from making experiments in this direction, as our laboratory is not equipped for experi- 

 mental work with animals, and with the great quantity of strains here concerned, it was 

 likewise impossible to carry out the work as guests at any other laboratory. The results 

 obtained by such agglutination experiments are, however, not always 

 of the same interest from the systematic point of view, since, as will appear 

 from M. Christi.a.nsen's work on the bacteria of the typhus-coli group*) the character 

 of the agglutination need not always cover definite morphological, cultural or biological 

 qualities. And this agrees excellently with the fact that, as we have mentioned, the 

 bacteria are able to adapt themselves to new proteins. Among the most variable proteolytic 

 qualities in bacteria are the hæmolytic, and, as we know, everything connected with 

 pathogenity at any rate for the pathogenic bacteria coming into our sphere of work (certain 

 strepto- and micrococci) is among the qualities soonest lost on cultivation in artificial 

 substrates. On the other hand, the researches of C. O. Jensen render it likely that non- 

 virulent coU bacteria — and in analogy therewith, also other non-virulent bacteria — can 

 under certain conditions become pathogenic, (consequently, the pathogenic quali- 

 ties cannot be utilised at all as species character, but merely serve to 

 indicate whether we are dealing with a pathogenic variety. 



In Lehmann and Neumann's »Bakteriologische Diagnostik" (5. Edition 1912) 

 taurocholate of sodium is used to separate off Sc. pyogenes from the remaining strepto- 

 cocci. If 5 — 10% of this salt be added to broth cultures 24 hours old, of the various strepto- 

 cocci, then their cells should dissolve in the course of some few minutes, save in the case 

 of cells of Sc. pyogenes. This seems most mysterious to begin with, and involves the unfor- 

 tunate conclusion that no streptococci other than Sc. pyogenes could live in the intestinal 

 canal of animals, or at any rate, in that of carnivores. We on our part have never succeeded 

 in observing the slightest clearing in broth cultures of any of our strains on addition of 

 taurocholate of sodium, far less any real dissolution of the cells perceptible under 

 the microscope^). 



Another reaction largely used for identification of streptococci is that based on their 

 various power of reducing colouring matter. For this purpose, milk stained a 

 pale blue with litmus*) is chiefly used. With like quantities sown out, and at like tempera- 

 tures (which should preferably be somewhere near the optimal temperature for the bac- 

 teria in question), the power of reduction will be proportional to the time taken in decolo- 



>) Meddelande Nr. 68 från Centralanstalten for försöksväsendet på jordbruksomrâdet. 1912. Tbm. 

 Joghurt, which is otherwise nearest to Tbm. helveticiini. agglutinates, however, together with Tbm. 

 btilgaricum. 



-) Det kgl danske Videnskabernes Selskabs Skrifter, naturvidenskab, og matematisk Afd. 191Ü. 

 8. Række, I, 3. 



We made our experiments with a preparation from Merck, and as this proved to contain at 

 least as much sodium glycocholate as sodium taurocholate, we have ourselves prepared pure tauro- 

 cholate of sodium from gall, by precipitating the sodium glycocholate from the mixture of gallic acids, 

 with sugar of lead, and then removing the lead by means of sulphuretted hydrogen. Even the pure 

 salt, however, gave no better result. It is only the cells of Sc. lanceolatus and Sc. mucosus, which are 

 dissolved by taurocholate of sodium. 



<i As milk, like other sugar-containing liquids, decolorises litmus during sterilisation, the litmus 

 tincture must be sterilised separately, and dropped into each tube with a sterile pipette. 



