ESMOND E. SNELL 



of thousands of microbial species. Only a dent has been made 

 in the problem of the nutrition of protozoa and insects. 



The discovery by Fraenkel (1 5b) of vitamin B-p as an essential 

 growth factor for the meal worm, Tenebrio molitor, and its iden- 

 tification as carnitine by Carter (9b), a compound that also occurs 

 in higher animals but whose function is unknown, illustrates the 

 fruitfulness of investigations of the nutrition of the currently 

 neglected lower animals. Having discovered the factors required 

 in common by most living species, we may be on the verge of 

 discovering those nutrients characteristically required by a 

 restricted number of species (c/. D-alanine) . If such nutrients 

 exist, knowledge of them would be invaluable in permitting design 

 of antimetabolites directed against specific groups of organisms. 



In bacteria, appropriate nutrients can sometimes partially 

 overcome the deleterious influence of certain drugs {cf. the effect 

 of glutamine on alcohol tolerance in some bacteria (50)). 

 Similar relationships should hold in animals and provide a large 

 area for investigation. Proper nutrition practice has already 

 reduced the incidence of many of the infirmities of old age. 

 Can further progress along these lines be made ; can, indeed, the 

 aging process itself be slowed? 



Such questions suggest that, far from being an obsolescent 

 field, the future may hold triumphs for experimental nutrition 

 equal to those of the past. 



References 



1. Angier, R. B., J. H. Boothe, B. L. Hutchings, J. H. Mowat, J. Semb, 

 E. L. R. Stokstad, Y. SubbaRow, C. W. Waller, D. B. Cosulich, M. J. 

 Fahrenbach, M. E. Hultquist, E. Kuh, E. H. Northey, D. R. Seegar, 

 J. P. Sickels, and J. M. Smith, Jr., Science, 703, 667 (1946). 



2. Barton-Wright, E. C, The Microbiological Estimation of the Vitamin B 

 Complex and Amino Acids. Pitman, London, 1952. 



3. Bessey, O. A., H. J. Lowe, and L. L. Saloman, Ann. Rev. Biochem., 22, 545 

 (1953). 



4. Bond, T. J., T. J. Bardos, M. Sibley, and W. Shive, J. Am. Chem. Soc, 

 71, 3852 (1949). 



4a. Brink, C, D. C. Hodgkin, J. Lindsey, J. Pickworth, J. H. Robertson, 

 and J. G. White, Nature, 174, 1169 (1954). 



110 



