484 IX. CAROTENOIDS AND VITAMINS A 



will be recalled that Kon and Thompson*''^ had reported that the latter 

 species contained a considerable proportion of vitamin A. Drummond and 

 Gunther*^" concluded that vitamin A as such is apparently present in only- 

 small amounts in phytoplankton, and is entirely absent from zooplankton. 

 The phytoplanktons studied were a diatom {Chaetoceras spp.) and a spring 

 diatom from the Irish Sea {Lauderia horealis), while the types of zooplank- 

 tons investigated included mixed copepods and a subarctic pelagic copepod 

 {Calanus finmarchicus) . Three reports state the absence of vitamin A in 

 the last species. '''*^'*^^'*^2 On the other hand, Gillam and co-workers'*^^ 

 did find vitamin A in these invertebrates; the maximum amounts of vita- 

 min A coincided with the period of maximum phytoplankton occurrence, 

 and with the zooplankton breeding season. Fisher and colleagues*^® 

 recorded the presence of small amounts of vitamin A in the pelagic plankton 

 copepod {Euchaeta norvegica) . 



Vitamin A has also been demonstrated in some of the higher members of 

 the crustaceans and cephalopods. Thus, this vitamin was found in the 

 amount of 600 I.U./g. in the oil extracted from the viscera of the edible 

 Pacific crab {Cancer magister) by Pugsley.*^* Wald^^^ reported that 1 to 2 

 Mg. of vitamin A Avas found in the retina of the squid {Loligo pealii) . Ap- 

 proximately three times as much retinene was present in this tissue. Vita- 

 min A was likewise shown to occur in the eyes of the fiddler crab {Uca 

 pugnax) and the green-shore crab {Carcinides maenas), as well as in those 

 of an unspecified variety of lobster, but no retinene was found. Both 

 vitamin A and retinene, as well as astaxanthin, were found in the eyes of 

 the freshwater crayfish (Camhariis virilis)^^^ On the other hand, Fisher 

 et al.'^^^ could find no vitamin A in the amphipods, isopods, or water-fleas 

 (Cladocera) . 



According to Neilands''^® the American lobster (Homarus americanus) , 

 is able to convert carotene to vitamin A ; thus on a carotene-free and on a 

 carotene-containing diet, the concentration of vitamin A in the hepato- 

 pancreas was 36 and 53 I.U./g., respectively, while that in the eyes was 100 

 and 183 I.U./g., respectively. Vitamin A was found to be present in 

 loAver concentration in the Decapoda than in the Euphausidae, since the 



«» J. C. Drummond and E. R. Gunther, Nalure, 126, 398 (1930); /. Exptl. Biol., 11, 

 203-209 (1934). 



«' G. Collin, J. C. Drummond, and T. P. Hilditch, /. ExplL Biol, 11, 198-202 

 (1934). 



«2 E. Lederer, Bull. soc. chim. bioL, 20, 567-610 (1938). 



«3 E. Gillam, M. S. El Ridi, and R. S. Wimpenny, /. Exptl Biol, 16, 71-88 (1939). 



*5* L. I. Pugsley, /. Fisheries, Research Board, Can., 5, 344-346 (1941). 



«5 G. Wald, Am. J. Physiol, 133, 479-480 (1941). 



«« J. B. Neilands, Arch. Biochem., 13, 415-419 (1947). 



