372 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



water with the animals is removed by means of a pipette, and treated 

 as follows : — 1 drop of the narcotising fluid, consisting of hydrochlorate 

 of cocaine 1 grin., methyl-alcohol 10 c.cm. Distilled water 10 c.cnUis 

 added at intervals of five minutes and mixed, until it is seen that most of 

 the rotifers have fallen to the bottom of the tube. Then they are imme- 

 diately killed and fixed by adding as many drops of 1 p.c. osmic as the 

 tube contains c.cm. of fluid, and mixed. After ten minutes the animals 

 are removed with a pipette and washed in 1 or 2 p.c. commercial forma- 

 lin, and finally preserved in the same fluid. The non-pelagic rotifers, 

 creeping and living upon aquatic plants, are obtained by placing a quan- 

 tity of the plants in a large jar or bucket with just enoughlwater to cover 

 them, and leaving them there for several hours. Asphyxiation will soon 

 drive the animals to the surface film and ' near the light, where they are 

 collected and treated as before. The author considers that this method, 

 which in its main features is that of Rousselet, will preserve a large 

 number of rotifers in a fairly extended condition, and suitable for 

 systematic study. 



Cultivation of Anaerobic Organisms applicable to Water Analysis.* 

 A. Guillemard employs the following method (fig. 48) : a large Pasteur 



Pig. 48. 



pipette, with a content of 9-10 c.cm., pointed at its lower and narrowed at 

 its upper part, to which is attached the hydrogen apparatus, which 

 serves to replace the air of the pipette and the culture tube by hydrogen, 

 and also to aspirate the culture into the pipette. The medium being 

 liquefied and inoculated with the water to be tested, the pipette is flamed 

 and attached to the hydrogen apparatus, from which a rapid current of 

 gas is passed ; after closing the cock P, the pipette is placed in the 

 culture tube and wedged in with wool ; the cock P is then opened gently, 

 and a continuous current of hydrogen is passed for a few minutes, when 

 the cock R 1 connecting with the gasometer is closed, and the cock R 2 on 



* Ann. Inst. Pasteur, xx. (1906) p. 155. 



