H. C. HAMPTON AND L. G. M. BAAS-BECKING 637 



reliability. Only smooth, finished curves were used for calculation. 

 These were produced in experiments in which the ground plant was 

 mixed thoroughly with the peroxide. In connection with these 

 remarks a quotation of Pickering is given : 



"The application of the graphic method requires a great amount of care and 

 close attention to experimental and other conditions, and it is to be feared that 

 hurried use of it by those who have not taken the trouble to master the necessary 

 details, or to acquire the requisite amount of skill, may bring it into undeserved 

 disrepute." 



It is almost unnecessary to say that we used for our calculation 

 the formula of van't Hoff 



1 n. 



K = rT:r7. log 



0.434^ a - X 



In the few cases to which this formula did not apply we used others. 

 All the determinations were made at ± 17°C.(16-18°C.). The 

 temperature of the sea water was invariably 15°C. 



Catalase of the Undamaged Plant. — Catalase is an intracellular 

 enzyme and is supposed to adhere to the cells with great tenacity. 

 The extent to which the material is ground has a marked effect upon 

 the result. Long and thorough grinding in a mortar reduces the alga 

 to the consistency of an unguent. With the material in this condition 

 we obtained our best results. At first we washed off the adhering 

 sea water with distilled water before the gruiding, thinking that the 

 salt water might injure the enzyme. We were very much surprised, 

 however, to find that these preliminary v>^ashings reduced the enzyme 

 strength one-half, whereas a treatment with sea water had no effect 

 at all. 



3 gm. of Ulva + 3 cc. of unneutralized peroxide, ground without washing, gave 

 the following. 



