PETERS. — METABOLISM AND DIVISION IN PROTOZOA. 495 



This experiment permits the following tentative conclusions: (1) Sten- 

 tor is well adjusted to Na 2 HP0 4 and to CaCl 2 . (2) The low results of 

 the combination Na 2 HP0 4 + CaCl 2 were due to a sudden loss in one set 

 of ten out of five such sets (50 Stentors). We may therefore infer 

 from the uniformity of the other four sets, that Stentor is also well 

 adjusted to this combination. Subsecment experiments uphold this view. 

 (3) Stentor is not at all adjusted to excess of acid or alkali. 



Expt., Jan. 9, 1903. 



Stentors good, but slightly pale. Chemical conditions of solution like 

 those of di-sodic phosphate + calcic chloride solution. 



00050 m. CaClo 



Medium. hr. 1 da. 3 da. i da. 8 da. 



and ^ . . 50 57 57 59 59 



.00050 m. K 2 HP0 4 J 



Thus far the result indicates that Stentor is equally well adjusted to 

 di-potassic phosphate and to di-sodic phosphate, when either is in com- 

 bination with calcic chloride. 



Expt., Jan. 14, 1903. 

 The Stentors used in this experiment were pale and not well fed. 



Media. da. 1 da. 



.00100 m. CaCl 2 50 47 



.00100 m. KC1 50 7 



.00100 ra. KNOg 50 1 



.00100 m. MgS0 4 50 10 



.00100 m. K 2 HP0 4 50 10 



Of this list of physiological salts used singly and in hypisotonic concen- 

 tration calcic chloride shows a mean result near unity and stands in 

 marked contrast to the low values for the other salts. This effect is in 

 harmony with the curves of the preceding section, where the same com- 

 parative results appear. It suggests the use of calcic chloride as a basis 

 of comparison between different experiments when it occurs as a common 

 factor in each. It gives a measure of the metabolic pitch characterizing 

 the experiment. 



