ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 583 



B. Technique.* 

 (1) Collecting- Objects, including Culture Processes. 



Purification of Crude Silk Peptones, f — I. Walker Hall has devised 

 a method for the removal of the pigment of crude silk peptone (a mixture 

 of the hydrolytic products of the original silk fibre) by filtration through 

 argilla-alba. After three filtrations the residue is washed with distilled 

 water, and the total filtrates are evaporated almost to dryness. The 

 viscid mass is extracted several times with hot methyl-alcohol, the residue 

 powdered, dissolved in water, and the process repeated. The extracts are 

 poured into ethyl-alcohol, filtered off and placed in a vacuum. The 

 filtrates are allowed to stand for 24 hours, and the flocculent precipitate 

 removed as a second peptone. The products are tested for their peptone 

 contents. Purified silk peptone provides a valuable medium for bacterio- 

 logical purposes. 



Cultivation of Pathogenic Spirochetes. J — J. W. McLeod and 

 A. R. B. Soga have devised a simple method for the obtaining of anaerobic 

 conditions with the valuable though complex fluid media introduced by 

 Noguchi. A test-tube is fitted with a perforated rubber bung, and a 

 bent glass tubule with a capillary end is introduced to within a short 

 distance of the lower end of the bung:. The test-tube is now half filled 

 with pepton bouillon, which is then boiled. On cooling, a portion of 

 sterile rabbit's kidney is introduced, and a piece of cotton-wool, which 

 has been threaded through a glass bead, is soaked in the inoculating 

 material and dropped into the test-tube. Ascitic fluid is then run in to 

 near the mouth of the test-tube, and the bung introduced. As the bung 

 is pushed downwards, so the fluid rises in the narrow tube until it 

 reaches the bent portion. The capillary end is then sealed off. Fluid 

 can be easily drawn off at any stage of culture and subculture prepared. 

 This method is capable of general application to the cultivation of 

 anaerobic bacteria, with the exception of such as cause active gas form- 

 ation. 



Culture of the Plankton Diatom Thalassiosira gravida. § — E. J. 

 Allen gives the following summary of his investigations as to the artificial 

 cultivation of diatoms. Attempts to obtain good cultures of Thalassio- 

 sira gravida in a purely artificial medium, made by dissolving in doubly 

 distilled water Kahlbaum's pure chemicals in the proportions in which 

 the salts occur in sea-water, adding nitrates, phosphates, and iron accord- 

 ing to Miquel's method and sterilizing the medium, have not succeeded. 

 If, however, a small percentage of natural sea-water (less than 1 p.c. 



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

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

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

 (6) Miscellaneous. 



t Journ. Path, and Bact. (1914) xix. pp. 286-304. 



% Journ. Path, and Bact. (1914) xix. pp. 210-13 (1 fig.) . 



§ Journ. Marine Biol. Assoc, x. (1914) pp. 417-39. 



