Vol. XI. No. 274. 



THE AGRICULTURAL NEWS. 



339 



conditions of climate. Another is: to what extent do 

 strains showing very marked differences in virulence 

 occur in one species of parasitic fungus. While yet) 

 another is: to what extent do certain species of partly 

 parasitic fungi, such as Thyridaria tarda, found 

 throughout the tropics on several host plants and 

 originally probably pure saprophytes, exhibit before 

 our eyes a process of developing parasitism, becoming 

 at the same time specialized to the host plant predom- 

 inating ill any given locality. So many partly 

 parasitic fungi are of universal distribution in the 

 tropics, and are capable of attacking several host plants, 

 that it seems very possible that some of them may 

 actually afford instances of the progress and specializa- 

 tion of ])arasitisiii. 



The investigation of problems of the nature of 

 those just considered belongs in a sense to the realm 

 of pure research, and requires more time than is usually 

 available to the plant pathologist engaged in pioneer 

 or routine work. In fact such investigation bears 

 much the same relation to routine plant pathology 

 that medical research does to the work of a general 

 practitioner. The future may prove that the parallel 

 can be carried farther; and that the solution of these 

 problems is as important to the economic welfare of 

 an agricultural community as the results of medical 

 research are to its bodily health. 



PELLAGRA. 



Informiation concerning this disease, which is 

 common in parts of the West Indies, is contained in an 

 abstract of a paper, given in the Bulletin of Agricul- 

 tural Information and, of Plant Diseases, August 

 1912, p. 1701:— 



The investigation of pellagra moves now essentially on 

 bacteriological lines. It differs from the preceding diseases, 

 [beri-beri, polyneuritis, epidemic dropsy and scurvy] in 

 in that it cannot be produced experimentally in animals. 

 Pellagra, which was known in Italy in the eighteenth 

 century, now occurs in Italy, Roumania, Austrii, Spain, 

 Portugal, Egypt, Algeria, United States, Mexico and Central 

 America; it is strictly limited to districts where maize is 

 used as the staple diet. The disease, which breaks out 

 mostly in spring and autumn, shows nervous and psychic 

 symptoms and leads often to general cachexia, diarrhoea, and 

 suicide. A very characteristic symptom is an erythema of the 

 skin, which is caused by the sun and is localized in uncov- 

 ered parts of the body. 



In addition to such views as those expressed by Hodson, 

 that pellagra is not a definite disease, there exist five 

 distinct theories — namely, the intoxication, autointoxica- 

 tion, infection, photodynamic and deficiency theories. 



According to the fir.st, held by the Italian authors 

 (Ceni, Otto, Lombroso, Go-oio, Gavina, BertarelU, Antoniiii, 

 Camuzzi), the disease is caused by toxic sulistances produced 



in maize by the action of microorganisms, especially fungi 

 (Aspergillus, Penicillium, etc.). The ferments capable of 

 producing the toxic substances remain active even after 

 cooking. 



According to the auto-intoxication theory (v. Neusser, 

 De Giaxa) pellagra is due to toxic products formed in the 

 intestine under the influence of certain bacteria, especially 

 of B. eoli. 



As regards the infection theory, an enormous amount of 

 different organisms have been credited with the power of 

 causing pellagra: a particular strain of Penicitlium. glaucum, 

 Aspergillus iuwescens and A. fumigatns; Streptobacillus 

 pellagrae, a protozoon transmitted by a biting fly of the 

 genus Simulium. 



But post-mortem bacteriological investigations (Raubit- 

 scheck) revealed nothing in favour of the infection theory of 

 the etiology of pellagra and the sero-diagnostic examination 

 of the blood did not show the presence of antibodies against 

 maize proteins or germs contained in maize. 



According to Raubitscheck's theory, spoiled maize pro- 

 duces a toxic substance, which is able to sensitize the skin 

 for sun rays. 



The deficiency theory is the one brought forward by the 

 writer [C. Funk]. He draws attention to the fact that the diet 

 in pellagra districts is very onesided and consists chiefly of 

 starch, which is known to produce beri-beri. Maize prevents 

 beriberi and scurvy, as do beans, vegetables, milk and 

 potatoes; these appear, though in very small quantitie.s, in 

 the diet described by Lombroso and Camuri. Thus I )r Funk 

 concludes that pellagra is due, probably to the deficiency of 

 a vitamine* different from those of beri-beri and scurvy. 



Food has, till now, been valued only by its content 

 in proteins, fats and carbohydrates, and calories value; but 

 the nutritive value of the proteins depends on their amino- 

 acid content. An animal fed on proteins which differ in the 

 quantity of amino acids from the proteins of its own body 

 is forced to use much more proteins and is unable to use 

 these amino-acids, which are in larger proportion in the food 

 than in its own body. In future, the amino-acid vitamine 

 content will have to be considered. 



It is to deficiency in vitamine that the fact must be 

 attributed, that proteins which contain sufficient amino-acids 

 to maintain adult animals in nitrogenous equilibrium, prevent 

 normal growth in young animals. A deficiency in vitamines 

 produces also a predisposition to many other diseases, among 

 which rickets mav be mentioned. 



DEPARTMENT NEWS. 



The Imperial Commissioner of Agriculture left 

 Barbados by the S.S. 'Guiana' on October 20, for an 

 official visit to Antigua. Dr. Watts is expected to return 

 to Barbados in about three weeks' time. 



Mr. H. A. Ballou, M.Sc, Entomologist lo the 

 Department, left Barbados for St. Vincent by the 

 S.S. 'Oruro' on October 17, in order to make investiga- 

 tions regarding insect pests in the island. 



* Vitamines are substaiice.s (organic bases) present in small 

 4uantities in foods, which are able to prevent or cure such 

 diseases as beri-beri and scurvy. Their insuffiency in the diet 

 appears to cause the exhibition of those diseases. — Ed., A.N. 



