772 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and differences in American and European forms. Mr. T. B. Bosseter, 

 F.R.M.S., gave an historical account of the family Taeniidae, and a 

 sketch of his own work on Hymenolepis, and the methods he employed 

 in obtaining and preparing specimens of these Platyhelminths for 

 examination. 



B. Technique.* 

 (1) Collecting Objects, including Culture Processes. 



Influence of the Composition of the Medium on the Solvent 

 Action of certain Soil Bacteria.! — 0. W. Brown has studied the 

 influence of the composition of the medium upon the solvent action of 

 certain soil bacteria. The materials experimented upon were finely 

 powdered rock phosphate, bone, tricalcium phosphate, dicalcium phos- 

 phate, and calcium carbonate. These were shaken up in water, and a 

 little of the washed powder put into a flask of medium and sterilised for 

 15 minutes ; after cooling to 60° C. the particles of powder are dis- 

 tributed through the medium by shaking, plates are poured, and 

 inoculated by a stroke on the surface of the solidified medium, and 

 incubated at 22° C. With ordinary nutrient agar there was no visible 

 dissolution of any of the five minerals. With agar containing 2 p.c. 

 dextrose, several germs showed an action upon calcium carbonate, 

 dicalcium phosphate, and tricalcium phosphate, but there was no visible 

 action on bone or rock phosphate. 



A synthetic agar medium composed of 0*02 p.c. magnesium sul- 

 phate and ammonium sulphate and 2 p.c. agar, was then used both with 

 and without sugars. The results showed that no germs had any action 

 in the plates containing no sugar, but with 1, 2, and 4 p.c. dextrose, 

 some germs acted on calcium carbonate, and on dicalcium and tricalcium 

 phosphate ; there was no action on bone or on rock phosphate. 



The solvent action of some germs was greater in the presence of a large 

 percentage of sugar ; that of others being as great with 1 p.c. as with 

 4 p.c. If meat infusion was substituted for the water in the synthetic 

 medium, the solvent action of the germs was less. On using a medium 

 composed of soil leachings with 2 p.c. agar, no action was noticed, but 

 on the addition of sugar to this medium, the results were similar to 

 those obtained with the synthetic medium. It was found that those 

 germs which in the presence of sugar were the most active acid 

 producers, were those that showed the greatest solvent action. 



Plate-cultivation of the Streptobacillus of Ducrey.i — R. Stein 

 finds that the streptobacillus of soft chancre will grow well on rabbits' 

 blood agar plates if kept in a moist chamber to prevent drying. The 

 waxy, shining, whitish-grey colonies have no growth in the depth of the 

 medium, and can be easily removed from the surface of the plate. 



» This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes ; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, etc. ; 

 (6) Miscellaneous. t Mich. Acad. Sci. Rep., ix. (1907) p. 160. 



J Centralbl. Bakt. lte Abt. Orig., xlvi. (1908) p. 664. 



