1914] William N. Berg 179 



for very concentrated Solutions of potassium carbonate), which 

 varies from 71 to 85 dynes per cm. for the aqueous Solutions of 

 most inorganic salts. From the data in the literature, one might 

 infer that the surface tension of Chondrioderma ought not exceed 

 that of other aqueous Solutions or suspensions of comparable com- 

 position. It should, therefore, be somewhere in the neighborhood 

 of 85 dynes per cm., or below. But according to Jensen's calcula- 

 tions, it is 6000 dynes per cm.. One reason for doubting the cor- 

 rectness of this figure has already been mentioned, namely, the fact 

 that surface tensions as high as this are not to be found recorded in 

 the literature, for any substance. Secondly, Jensen apparently over- 

 looked the fact that the circumference of a circle is 27r times the 

 radius and not tt times the radius, which is the expression used in 

 Jensen's^ formula, with the result that a quotient of 6000 ought to 

 be 3000. 



A somewhat similar error was made in our own calculations 

 already publisht,^ insofar as the value of tt was accidentally omitted 

 from the value for the reduction in area when i cc. of muscle con- 

 tracts. The value previously obtained, 1000 sq. cm., should be a 

 little over 3000 sq. cm., with corresponding changes in the results. 

 So many assumptions had been made in favor of the surface tension 

 theory, that no change was necessary in the final conclusion, namely, 

 that the surface-tension theory of striated muscle contraction as 

 advanced by Bernstein, by Macallum and others, is untenable. It 

 is rather remarkable that altho Bernstein's^^ calculations showed 

 that surface energy was insufficient (p. 295), and he realized the 

 insufficiency, he still advocated the theory as being correct in prin- 

 ciple (p. 141). 



8 Jensen, loc. cit., p. 841 : " Diese (the surface tension) ist berechnet aus dem 

 Gewicht, das ein Pseudopodienbündel von bekanntem Gesamtumfang zu heben 

 vermag. Die Berechnung geschah nach der Formel a = p/'^r, wo a die Ober- 

 flächenspannung, p die Zugfestigkeit eines Pseudopodiums und r sein Radius 

 ist." Jensen used this same formula in the two widely differing cases of a 

 thread (Orbitolites) that lifts a weight and a thread (Chondrioderma) that sus- 

 tains a weight. This is the probable reason for the great difference between the 

 surface tensions of Orbitolites and Chondrioderma and not as proposed by 

 Macallum {loc. cit., p. iii) : "It is not improbable, therefore, that surface tension 

 may be very high in some forms of living matter and very low in others . . ." 



^Berg: Biochemical Bulletin, 1912, ii, pp. 107-109. 



10 Bernstein : Arch. f. d. gesammte Physiologie, 1901, Ixxxv, pp. 271-312; 

 1909, cxxviii, pp. 136-141. 



