DIETKTIC DEFICIENCY. .297 



C(intribiitinsT to the formation of tissue, and in i(ji2 TTopkins and 

 Neville ])nbHshecl results analogous to those of Sle])]), in which 

 they eni])hasisecl the importance of the alcohol-soluble fraction 

 of a feeding composite. 



The general position, then, a few years ago, may l)e summa- 

 rised by saying that the dietetic significance of certain " minimum 

 substances " was recognised ; which siibstances might either be 

 lipoid in character, or nitrogenotts bodies cont;!ining nuclei like 

 those occurring in the ainino-acids of i)roteins. 



While all this work on feeding problems was ])roceeding — 

 i.e.. from abotU the beginning of the present century onwards — a 

 great deal of research was also being carried out u])on the natiu"e 

 of certain obscure diseases, notably beriberi, the origin of which 

 ap])eared to be traceable to dietetic deficiency of a sjiecific kind. 

 About T912 Casimir Ftmk introduced the name " vitamine '" to 

 denote a specific class of food constituent, the absence of \\hich 

 in an otherwise normal diet involved metabolic disturbance 

 resulting in malnutrition or in specific disease. 



" The " vitamines " belong to the group of " accessory " or 

 " minimal " sul)stances already mentioned, which are almost inva- 

 riablv present in all ordinar}' foods, but which under al)normal 

 circitmstances may l^e al)sent. Within the last few years h'unk 

 has made a special stud\' of these substances, and done a great 

 deal towards elucidating their chemical natiu-e. To a condition 

 resulting from a vitamine deticienc)' he ap]:)lies tlie term " avita- 

 minosis," and within the categor\- of such diseases he brings 

 either definitely or tentatively : — 



(1) The Beriberi grou]). including ])olynem"itis in birds. 



(2) The Sctirvy group, including Barlow's disease. 



(3) Pellagra (and Si>rue). 



(4) Rickets and Osteomalacia. 



(5) Diseases knoMU in Ormanv as " ]\Tehlnahrscliaden " 

 and " Milchnahrschaden." 



(6) T.amziekte and stijfziekte in cattle. 



Under a final heading he also discusses the \itamines in 

 relation to growth, to the problem of cancer and tumour growth, 

 and to various ])r()blems of ])lant and animal metabolism. 



It would occu])y too much of your time to present all the 

 aspects of avitanunosis as raised by ]^\mk,* and since much of 

 his disctission, thotigh in itself very illunu'nating, is speculative, 

 we may first confine our attention to those instances of \itamine- 

 hunger in which the evidence is clearest. 



Beriberi. — It was in the study of this disease that the experi- 

 mental evidence ultimatel}- crystallising in the concejition of 

 vitanu'ne-hunger was chiefly obtained. The malady occtirs mainly 

 in tropical and su1)tropical zones, and almost exclusively amongst 

 rice-eating i)eo])les. Particidarlv during the last (|ttarter of a 

 century it has excited enormous iiUerest, and yet tmtil recently 



* " Die Vitamiiu', ihre Bedentuno fiir die Physiohigie tind Patliulogie." 

 (1QI4). 



