128 Comparative Animal Physiology 



deficiency of pantothenate than from that of any other B vitamin. Royal jelly 

 of honey bees contains three times more pantothenic acid than yeast or 

 liver. ^^^ Ruminants obtain an adequate amount from their symbiotic flora, 

 pantothenic acid increasing by 6 to 25 times in the rumen. ••^- "'' and rabbits 

 excrete as much as 265 fxg. daily on an intake of 17 ^g. ^°-^ Even in man 

 pantothenic acid is synthesized by colon bacteria and some may be absorbed. 

 Numerous pathological lesions have been reported in pantothenic acid defi- 

 ciency. There is initial stimulation and ultimate exhaustion and even atrophy 

 of the adrenal cortex. -'^ 



Trout need approximately 1.1 to 1.4 mg. of pantothenic acid per kilogram 

 per day to prevent a characteristic disease of the gills. ^°" In pantothenic acid 

 deficiency fur-bearing animals, such as the fox, show pathological symptoms in 

 hver and kidney, ^^'-^ and monkeys show lack of growth, thin fur, and anemia. 

 "^ Growing chicks and ducklings require much pantothenic acid and when 

 deficient show dermatitis and nerve degeneration; if laying hens are on a defi- 

 cient diet their eggs are fertile, but embryonic mortality is high. 



Biotin. Biotin is: 



O 



II 



c 



/ \ 



HN NH 



1 I 



HC CH - CH, - CH. - CH. - CH. - CO.H 



I I 



H.C C 



\ /H 

 S 



Biotin was discovered independently as needed by certain yeasts, by nitrogen- 

 fixing bacteria, and by mammals. Biotin may act in the conversion of pyruvic 

 acid to oxaloacetic acid by COo fixation. '" A diet rich in raw egg white 

 causes a characteristic dermatitis in chicks, rats, rabbits, dogs, and monkeys; 

 this is cured by addition of biotin to the diet. 



Biotin is not essential in the diet for the growth of the ciliate Tetrahy- 

 mena. '''' It has a pronounced stimulating action on the growth of flour 

 beetles and may be a component of the unkown yeast factors required by some 

 other insects. Mosquitoes fail to metamorphose without biotin in their 

 diet. ^^^ Biotin appears to be synthesized in the intestine by different bacteria 

 from those synthesizing some of the other B vitamins, and biotin synthesis is 

 favored by dextrin but not by lactose. Not enough is synthesized to satisfy 

 the needs of the hamster,-^ but probably enough is produced by symbionts in 

 rabbits.^"'' A deficiency in hens results in high embryonic mortality and perosis 

 or skeletal deformity in young chicks, which can be prevented by injection 

 of biotin into the incubating eggs.-'^' -"*• -'^ 



Folic Acid (Pteroylglutamic Acid). Folic acid is a B vitamin which has 

 spectacular effects in the treatment of certain types for anemia. It is needed 

 by Tetrahymena strain W but not strain £.-•*"• *^-'- *'"- " In a few insects such 

 as Triholiwn, Ephestia, and especially Tenehrio larvae (Table 24), folic acid 

 is essential for growth; it is particularly important in the third instar of Aedes 



