342 GASOMETRIC-MANOMETRIC METHODS 



acetate, and 0.5 ml. n-butyl phthalate. The thinnest fihn that Tobias 

 used and measured was about 20 m/t thick, although thinner films 

 proved adequate. 



B. MANOMETRIC 



Of the two manometric techniques which will be considered here, 

 Cartesian diver and optical lever manometry, the former holds the 

 more prominent position. The relative simplicity of the apparatus 

 and the great sensitivity and high precision of which it is capable 

 make the diver technique one of choice for many gasometric studies 

 on the histo- and cytochemical level. The diver has already been 

 applied to the gasometric determination of isolated enzymes and 

 other metabolic catalysts as well as to respirometry. Future devel- 

 opments can be expected to exploit extensively the many possibili- 

 ties of this versatile technique. 



1. Cartesian Diver Manometry 



The application of the Cartesian diver to the measurement of the 

 volume changes in small volumes of gas was conceived and first 

 elaborated by Linderstr0m-Lang (1937b). A short discussion of the 

 technique appeared in a subsequent report by Linderstr0m-Lang 

 and Glick (1-938). Certain technical changes were employed by 

 Boell, Needham, and Rogers (1939) and Boell, Koch, and Needham 

 (1939) in their noteworthy investigations dealing with the respira- 

 tion and anaerobic glycolysis of regions of the amphibian gastrula. 

 Other technical modifications were suggested by Rocher (1942, 

 1943). Theoretical aspects of Cartesian diver micromanometry have 

 been given a complete treatment by Linderstr0m-Lang (1942, 1943). 

 Following a study by Linderstr0m-Lang and Holter (1942) of the 

 diffusion of gases through liquid seals in the diver, Holter (1943) 

 presented a finely delineated description of diver technique which 

 contains a full complement of precise detail, and includes the refine- 

 ments and innovations subsequently introduced. Zeuthen (1943) 

 designed divers of even smaller capacities and worked out the details 

 of their use. 



The principle of the diver technique lies in the fact that any 

 change in the amount of the gas in the diver, which is used as a 



