ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 709 



are not flocculated by salts of potassium, sodium, or ammonium, like 

 particles of suspended inorganic matter, and consequently a pure floccu- 

 lation or coagulation cannot be employed as a means of separating 

 bacteria from cultures or of causing ultra-microscopical bacteria to 

 cohere into visible aggregates. Salts of lime form a precipitate of 

 calcium jmosphate with the phosphoric acid of the medium. Since 

 all ordinary media contain phosphates, and the organisms grown therein 

 always retain traces of phosphoric acid, any substance capable of forming 

 an insoluble phosphate will, when added to bacterial suspensions, cause 

 a precipitate to form, and this by entrapping the bacteria will produce 

 an apparent flocculation of the organisms. Bacteria when grown in 

 ordinary media exhibit different powers of precipitation with calcium 

 salts, Bac. typhosus requiring only one-fifth the amount required by 

 B. coli commune. Calcium chloride cati be employed as a means of 

 distinguishing between these two organisms. The method consists in 

 pipetting 2 ccm. of a two or three days' bouillon culture into a narrow 

 test-tube, and adding 1 ccm. of calcium chloride solution containing 

 1 grm. crystallised calcium chloride per 100 ccm. The mixture is shaken, 

 and allowed -to stand for an hour. At the end of this time B. typhosus 

 shows a well defined precipitate, and in an almost clear supernatant fluid 

 several large floccules adhering to the walls of the tube. On the other 

 hand, B. coli has an ill defined precipitate and a very turbid supernatant 

 fluid. 



Influence of Bacteria on the Decomposition of Bone.* — Prof. J. 

 Stoklasa records experiments on the influence of bacteria on bone de- 

 composition. The species used were B. megaterium, B. fluorescens 

 Uquefaciens, B. proleus vulgaris, B. butyricus, B. mycoides, B. mesentericus 

 vulgaius. These were cultivated in a medium containing bone-dust, 

 potassium sulphate, magnesium chloride, and iron sulphate, and after an 

 incubation of 20 days the amount of nitrogen and phosphoric acid was 

 determined as amid, diamin, andmonamiu nitrogen. The results showed 

 that bacteria, especially B. megaterium, B. mycoides, and B. mesentericus 

 ■vulgaris, are very effective agents in removing phosphoric acid and nitrogen 

 from bone. The laboratory experiments were confirmed by cultivating oats 

 in a hot-house with different composts and with different bacteria. The 

 composts used were superphosphate, Chili saltpetre, bone meal, bone meal 

 with glucose, and with xylose. The same three bacteria again stood at 

 the head of the list. 



Presence of the Members of the Diphtheria Group of Bacilli other 

 than the Klebs-Loeffler Bacillus in Milk.|— Dr. J. W. H. Eyre, who has 

 examined large numbers of samples of milk, states that several groups 

 of bacilli exhibiting segmentation, metachromatism, and clubbed invo- 

 lution forms, are occasionally present in retail milk. The bacilli of 

 these groups agree in resembling Bacillus diphtherias to some extent, 

 but are capable of being differentiated from it and also from each other. 

 They arrange themselves according to their colour-production into three 

 well-defined groups which are characterised by the coloration of the 

 colonies themselves in groups. In group 1 the colony is yellow, and in 



* Centralbl. Bakt. u. Par., 2 te Abt., vi. (1900) pp. 526-35, 554-60 (9 pis.), 

 t Brit. Med. Journ.. 1900, ii. pp. 426-7. 



