THE VITAMINES IN THE ANIMAL KINGDOM 85 



FISH 



As we progress in the animal series, we do not meet with any 

 vitamine experiments at least to our knowledge till we come to 

 fish, the single great group typical of the vertebrates, of which we 

 have no knowledge in this respect. There is only the work of Mor- 

 gulis (239) which might be considered to have some slight relationship 

 to our subject. He fed ox heart to fish and found that it is better 

 assimilated when cooked, while ox liver had no particular peculiari- 

 ties. Almy and Robinson (240), comparing dry and fresh fish food, 

 found that with the latter there was less mortality and a more definite 

 weight increase. 



AMPHIBIA 



Emmett and Allen (241) used frog larvae in their vitamine studies, 

 but the fact that the larvae consumed each other complicated the 

 experimental work somewhat. The larvae reacted poorly towards a 

 greater addition of fat, and developed better on a diet containing 5 

 per cent fat than on one containing 28 per cent. Both vitamines, A 

 and B, appeared to be necessary, although the latter seemed more 

 important. The variation of protein content from 10 to 30 per cent 

 was of no special significance, although the optimum growth was 

 obtained with higher concentrations. Lactalbumin or a mixture of 

 beef and oats was superior to corn gluten, indicating the importance 

 of the protein used. The growth of the hind legs depends upon 

 the addition of vitamine, according to the findings of Emmett, Allen 

 and Sturtevant (242) . For complete metamorphosis, the addition of 

 iodine also appears to be necessary. 



Harden and Zilva (243) investigated both larvae and adult frogs. 

 With tadpoles kept in water to which was added fresh meat, a normal 

 development was noted, while an experimental diet made up of 20 

 per cent casein, 75 per cent starch, 5 per cent salts with the addition 

 of butter, yeast extract, and orange juice, did not permit of normal 

 development, since only two out of six animals attained full growth. 

 According to this a better experimental diet had to be prepared. 

 With adult frogs, another difficulty presented itself in the develop- 

 ment of a fungus-like disease. On a diet free from vitamine B, some 

 of the animals stretched out their legs, before death, and one suffered 

 from convulsions. Without A- and B-vitamines, seven frogs died in 

 about four months. Out of five animals on a diet containing the 



