XIV 
CHEMICAL CONSTITUTION AND RELATIVE PHYSIOLOGI- 
CAL EFFICIENCY OF ACIDS! 
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 HCI, HNO;, and H,SO, 
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 réle 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. 
i Loeb, Biochem. Zeitschr., XV, 254, 1909; ‘‘An Improved Method of Arti- 
ficial Parthenogenesis,”” University of California Publications, Physiology, I1, 1905; 
Untersuchungen, p. 329, Leipzig, 1906. 
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