622 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The collector is to provide himself with several squares of well- 

 washed cotton cloth, about the size of a handkerchief, and bo at the 

 ground at low tide. Take a square of cloth and carefully lay it down 

 on the mud surface in a way not to include air-bells. The cloth will in 

 a few moments become wet, and may then be raised by one corner first 

 and folded up with the side that was next the mud on the inside. After 

 folding wrap in waxed paper and label for future reference. When 

 ready to clean, place the cloth in a porcelain evaporating dish, and cover 

 with strong sulphuric acid and enough bichromate of soda to make the 

 mass a deep reddish colour. Place the dish in a sand-bath over a gas- 

 stove or other source of heat, boil the mass till crystals of chromic acid 

 appear as scum on the surface of the liquid. Remove and let cool, 

 and pour into a preserve-jar partly filled with water. Let settle for at 

 least half an hour undisturbed, then siphon off the water with a rubber 

 tube to within 1 in. of the bottom of the jar, being careful not to disturb 

 the sediment. Repeat the washing till clear from all colour. The 

 sediment may now T be removed to a small bottle and excimined, and if a 

 small quantity of sand be present it may be removed by whirling it with 

 some water in the evaporation dish by means of a glass rod, and the sand 

 will be found to pile up in the centre as a dark spot. Carefully pour off 

 the water with the diatoms suspended in it, leaving the sand in the dish. 

 It is surprising how the diatoms will stick to the cloth, and how little 

 foreign matter will be collected by this method. 



Useful Medium for the Bacteriological Examination of Faeces.* 

 C. G. Delta recommends the following medium. To 100 c.cm. of 3 p.c. 

 agar, slightly alkalin to litmus, are added (1) \\ grm. of lactose, or any 

 sugar, dissolved in 4 c.cm. of distilled boiling water, and further boiled 

 half a minute ; (2) 10 c.cm. of \ p.c. aqueous solution of acid fuchsin, 

 brought to boiling point and discolourized by adding four drops of a 

 normal solution of sodium carbonate, and by boiling again until it 

 assumes a port-wine colour. The agar thus prepared presents all the 

 advantages and disadvantages of Endo's medium, but also has its own 

 special advantages, namely, it is very easily prepared from staple solu- 

 tions and is not affected by light. Furthermore (should one wish to 

 make this medium more differentiating), there may be added nutrose or 

 caffein, or malachite green or crystal violet (10 drops of 1 p.c. in 1000 

 solution). In the last two combinations the background is green or 

 blue, and the Bacillus coli colonies are violet or red. 



New Medium for the Culture of the Meningococcus.!— G-. Faroy 

 and Chavaillon recommend the following medium for the cultivation of 

 the meningococcus, as a substitute for the usual ascitic agar medium. 

 It is easily prepared, and, provided a stock of agar is kept on hand, is 

 eminently suitable for travelling or field laboratories. 100 c.cm. of sterile 

 horse serum is poured into a sterile flask containing glass beads, and)) 

 this 20 c.cm. of white of egg are added. (The large extremities of the 

 eggs are sterilized in the flame and pierced with a sterile forceps, the 



* Lancet (1915) ii. p. 1053. 



t CR. Soc. Biol. Paris, lxxviii. (1915) pp. 455-6. 



