ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



537 



kept at any constant temperature. He introduces the slide into a kind 

 of india-rubber stoppered larg:e test-tube. The stopper is perforated foi 

 the admission of a platinum thread (anode), and of a small tube termin- 

 ating in a small piece of platinum foil (cathode). This small tube 

 contains a few drops of mercury to facilitate the passage of the electric 



Jt la,ti. ne mfuii tin e«. 



1 



s 



Fig. 78. 



current introduced by a coil which sparks to at least 25 mm. The 

 stopper is also pierced by a small tube in connexion with an air-pump. 

 By regulating the current with a rheostat, and by controlling the air- 

 pump, the temperature of the interior, and therefore of the object-slide, 

 can be fixed as required. The apparatus has been found especially 

 convenient for the observation of crystal-formation. 



(8) Miscellaneous. 



Safety Mixing Cylinder.*— The practice of shaking emulsions of 

 infective material in the ordinary glass-stoppered measuring cyHnder is 

 attended with a certain amount of risk, and the subsequent removal ol 

 the stopper produces a fine spray of the fluid from the lip of the vessel. 

 To remove the danger of accidental infection from this cause, Lentz has 

 devised a special form of mixing cyUnder (fig. 79). It is shorter and 

 stouter than the ordinary type, and stands on a broad base. It is made in 

 70 and 100 c.cm. sizes, graduated respectively to o5 and 50 c.cm. The 



* Centralbl. Bakt., Ite Abt. Orig., Ixx. (1913) pp. 108-9. 



