1913] I' K. Phelps 91 



search Lahoratory of Parke, Davis and Co., Detroit, Mich.) As the 

 reaction of oxidases with hydrogen peroxide liberates heat, the 

 temperature factor as well as the expansion of the gas are very 

 important and necessitate a thermostat control with continued 

 agitation of the mixture for comparative studies. 



To obtain uniform temperature and continuous record of the lib- 

 erated gas, the following apparatus was devised. A shaking mem- 

 ber with two compartments, one for holding the hydrogen peroxide 

 and the other for the enzyme Solution, is connected by a tube with 

 ground Joint to a large cylindrical Container with its center at the 

 axis of motion so that liquid in this Container is not agitated by 

 motion around the axis. This arrangement allows the shaking of 

 the reacting Solution and the measuring of the liberated oxygen by 

 the water displaced. The large Container has a tube extending along 

 the axis to the outside of the thermostat, which allows the discharge 

 of the displaced water into a vessel suspended by a spring, so that a 

 writing arm can be made to record the volume, giving on a rotating 

 drum a curve which can be analyzed at one's leisure. 



Surface tension in muscle contraction. William N. Berg. 

 {Washington, D. C.) Macallum* quotes Jensen^ to the ef^ect that 

 " a thread measuring i mm. in diameter formed of the Plasmodium 

 of Chondrio derma, a Myxomycete, may, when it is in the dense con- 

 dition, bear up a weight of nearly a gram. If the force engaged is 

 surface tension it would amount to about 6000 dynes per centi- 

 meter. . . ." 



At the same time Macallum does not quote Pfeffer^ who, in dis- 

 cussing the mechanics of ameboid movement says, that in the case of 

 the Plasmodium of Chondrio derma, the outer membrane may vary 

 in its consistence from that of the fluid protoplasm in the interior of 

 the cell, to that of solid gelatinous masses. Chondrioderma have 

 the property of varying the consistence of the outer layer, and 

 Pfeffer regards the tougher outer layer as a physiological product 

 caused by reversible changes in cohesion. Pfeffer further states 

 that not until the outer layer has been brought back to its original 



4 Macallum : Jotir. Biol. Chem., 1913, xiv, Proc. Amer. Soc. Biol. Chem., p. xxii. 

 ^ Jensen : Anatomische Hefte, 1905, xxvii, p. 842. 

 6 Pfeffer : Pflanzenphysiologie, 1904, ii, p. 716. 



