64 



THE AMERICAN NATURALIST [Vol. XLI 



pinch cocks until the desired flow is obtained in each, necessitating, 

 however, more attention than the simpler form. The main features 

 of this apparatus are: its automaticity, its noiseless action making 

 it suitable for the class room or laboratory table, its simplicity and 

 inexpensiveness. 

 Detroit. Mich. 



