XIV 



CHEMICAL CONSTITUTION AND RELATIVE PHYSIOLOGI- 

 CAL EFFICIENCY OF ACIDS 1 



In my first experiments upon membrane formation I found 

 that the chemical constitution of acids is of great importance 

 with regard to their effect upon membrane formation. For 

 whereas carbonic acid and the weak monobasic fatty acids were 

 very effective, the strong acids, such as HC1, HN0 3 , and H 2 S0 4 

 or oxalic acid, had so little effect as to be practically useless for 

 these experiments. The oxy-acids were effective, but not to the 

 same degree as the monobasic fatty acids. The further investi- 

 gation of the relation that exists between constitution and effect 

 seemed to be full of promise, as it was to be expected that it 

 would give some information upon the role of acids in membrane 

 formation, and that the results might be of general importance. 



The following was the procedure adopted in the experiments. 

 The eggs were first freed from all sea-water by being twice 

 washed in an m/2 NaCl solution. They were then put into 

 solutions of the various fatty acids in m/2 NaCl solution, since 

 it was necessary to make the acid solution isosmotic with the 

 sea-water. At definite intervals a portion of the eggs was trans- 

 ferred by a pipette to normal sea-water, and the percentage of 

 eggs which formed membranes determined. 



I had discovered in my earliest experiments that the higher 

 fatty acids had more effect than the lower. Hence I suspected 

 that the activity of the monobasic fatty acids increased with 

 the number of carbon atoms. The results of one of a series of 

 experiments performed to decide this question are given in 

 Table XVIII. The temperature was about 15 C. 



iLoeb, Biochem. Zeitschr., XV, 254, 1909; "An Improved Method of Arti- 

 ficial Parthenogenesis," University of California Publications, Physiology, II, 1905; 

 Untersuchungen, p. 329, Leipzig, 1906. 



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