862 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



consists of a flat, round metal box (figs. 174 and 175, II), with a central 

 conical aperture. The entranco and exit pipes for the heated water 

 (fig. 175, Z, A) are set on at a right anglo to the side : the former, Z, 

 is a metal tube ; the latter, A, a glass one, is fitted with a thermometer, 

 the bulb of which, K, passes into the box. A current is maintained by 

 a partition S between the openings of the two pipes. These are sup- 

 ported by a stand (fig. 176), and their ends connected with rubber 

 tubes. 



Two precautions are necessary in using this apparatus. The first 

 is to get rid of all air-bubbles in the water, and the second is to 

 ascertain the temperature of the hot chamber. This is best done in 

 the manner described by Koch.* The materials employed by Dr. 

 Israel for ascertaining this latter point are a mixture of paraffin and 

 vaselin, from which a substance with the desired melting point is 

 easily prepared. Repeated trials with this apparatus show that if a 

 temperature of 37° C. be required for the hot chamber, the tempera- 

 ture of the water in the capsule must range between 42° and 47° C. 

 The apparatus can be adapted for direct heating after the manner of 

 Max Schulze's stage if so desired. 



Delage's Reversible Compressor. — Prof. Y. Delage has devised a 

 form of compressor for the most delicate observations, figs. 177 and 178, 



Fig. 177. 



Fig. 178. 



* Cohn's ' Bcitrage zur Biologie der Pflanzen,' ii. p. 284. 



