•032 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cisely because it is free from this objection, and the fact that it is not as 

 well suited for logarithmic work is of no importance where a calculating 

 machine is employed. The author proceeds to develop his algebraical 

 equations, which have the advantage of checking one another. More- 

 over, if the performance of the optical system should prove unsatis- 

 factory, it is probable that a comparison of certain corresponding 

 quantities would suggest what modifications are necessary to amend the 

 system in the direction desired. 



(6) Miscellaneous. 



Ultra-microscopic Investigation of the Tanning Process in 

 Jellies.* — W. Moeller gives a further description of the conditions of 

 formation of laminated structures in the action of aqueous solutions on 

 jellies. The formation of an insoluble salt by the interaction of an 

 electrolyte in the aqueous solution and a second electrolyte in the jelly 

 is not an essential condition in the production of such structures. It 

 has been found that an aqueous solution of silver nitrate when left in 

 contact with a gelatin jelly containing no added electrolyte gives rise to 

 the formation of alternating layers. The laminated structure would 

 seem to be produced when any ionizable salt diffuses into a jelly. The 

 same heterogeneous structure results when gelatin jellies are subjected 

 to the action of tanning solutions. It is considered that the ultra- 

 microscopic observations cannot be interpreted satisfactorily in terms of 

 the hypotheses previously set forward, and that the rhythmic lamination 

 can only be accounted for in terms of the structure of the jelly. The 

 author's view that gelatin consists of a fibrillated substance (a-gelatin), 

 the spaces between the fibrils being filled by a structureless substance 

 (/5-gelatin), is made the basis of an explanation of the rhythmic effects 

 which are the result of the diffusion processes which occur when jellies 

 are brought into contact with solutions of salts. 



"o* 



B. Technique. t 

 (1) Collecting Objects, including- Culture Processes. 



Medium for obtaining Anaerobes in Exudates.J — E. S. Harde 

 finds that the following medium gives good results : — 20 p.c. gelatin to 

 which is added 2 c.cm. of beef or veal. The tubes are then incubated 

 at 37 • 5. It is important to sow the tubes with much exudate. Pure 

 cultures are then made in the usual way. 



Method for the Rapid Determination of Bacillus diphtherias. §— 

 S. Costa, J. Troisier, and J. Dauvergne use the followiug medium : — Horse 



* Kolloid Zeitschr., xx. (1917) pp. 257-70. See also Journ. Chem. Soc, li. (1917) 

 p. 454. 



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

 cesses ; (2) Preparing Objects ; (3)Gatting, including Embedding and Microtomes 

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

 (6) Miscellaneous. 



X C.R. Soc. Biol. Paris, Ixxx. (1917) p. 661. 



§ C.R. Soc. Biol. Paris, Ixxx. (1917) pp. 678-80. 



