162 J. AWAPARA 
weeks they showed a decrease of approx. 40% in the concentration of free amino acids 
in muscle. The decrease was not equal for all of the amino acids measured but some 
decreased more than others. The greatest change observed was in the concentration of 
alanine, arginine, aspartic acid, glutamic acid and proline. 
Other invertebrates studied are some parasitic worms. The concentration of free 
amino acids in parasitic worms is not different from mammalian tissues. The total 
free a-amino nitrogen found for three species of anoplocephalid cestodes was measured 
by CAMPBELL’. He reports values for non-protein carboxyl nitrogen of 16, 13 and 
10 mg/t1oo g, whichis actually on the lower range for mammalian organs, and certainly 
very low when compared with marine crustacea like the lobster (Table IV). Many 
ideas have been proposed to explain the extremely high concentration of free amino 
acids in invertebrates. High concentrations of amino acids could be osmoregulatory. 
They could be products of protein breakdown and excretory products, but this would 
not explain easily the enormous difference in patterns which exist between one species 
and another. Dietary factors must be also considered but again difficulties would 
arise in explaining for example the extremely high concentration of glycine in some 
crustacea. This deserves further discussion. Glycine makes up about one-third of the 
total free amino acids in the lobster. Three other crustacea studied by us™ vary in 
glycine content considerably; in the Gulf Coast shrimp (Penaeus aztecus) glycine 
makes up also one-third or more of the free amino acid nitrogen (450 mg of glycine/ 
100 g), but in the hermit crab (Clibinarius vittatus) the concentration of glycine is 
only 45 mg/1oo g. In the crab Pagurus pollicaris the concentration of glycine is 
TABLE IV 
NITROGEN DISTRIBUTION IN WM. expansa, T. actinoides AND C. perplexa 
Values are expressed in mg/t10oo g wet wt. 


= 8 Non-protein : Protein 
Species pee N Rgds um carboxyl aie : carboxyl 
; N N 
M. expansa 544 88 35 414 321 
Range (425-767)  (7o-112) (24-53) (254-62) — (198-50) 
% of total N — 16.2 6.4 76.1 59 
T. actinoides 1296 1604 81 896 750 
Range (1159-1501L) (140-177) (58-105) (630-1081) (530-961) 
% of total N — Wee 6.3 69.1 58.3 
C. perplexa 1291 124 61 978 830 
Range (1217-1386) (110-136) (52-71) (846-1077) (685-885) 
% of total N _ 9.0 4-7 75.8 64.3 

intermediate between the two other crustacea, namely 150 mg/r1oo g. In all three, 
glycine was the most abundant of the a-amino acids. Comparisons of amino acids 
between various species have been attempted as means of speciation but with little 
success. GIORDANO, HARPER AND FILicEe!: compared the amino acid composition 
of blood from two taxonomically related species, the sea urchin and the starfish, and 
found that the composition was dissimilar. I do not believe that the study of patterns 
can be used for this purpose. Invertebrates are in an evolutionary sense very advanced 
and already possess all the biochemical characteristics of the mammals. Amino acids 
References p. 174/175 
