JANUAKY 31, 1913] 



SCIENCE 



185 



be commended for the clearness with which 

 physical principles are stated, and for the 

 numerous workable and practical problems. 

 That part of the text dealing with lenses and 

 with problems concerning- the eye is especially 

 to be commended. 



One feature of the text which distinguishes 

 it from others is the grouping together of 

 descriptions of demonstration experiments at 

 the end of each chapter. This is a matter of 

 considerable convenience to an instructor and 

 should prove interesting to a student. An- 

 other commendable feature is the large num- 

 ber of references to, or quotations from, other 

 texts or original articles. 



The author apparently has not attempted to 

 condense as great a number of facts and prin- 

 ciples as possible into the text, but has at- 

 tempted to present in an interesting form 

 what appears to him to be of most importance, 

 and he has succeeded. As a piece of book- 

 making the text is excellent. 



G. F. Hull 



Dartmouth College 



SPECIAL ARTICLES 



THE NUTRITIVE VALUE OF THE PROTEINS OF MAIZR 



The state of knowledge at present prevail- 

 ing concerning the nutritive value of corn- 

 meal when fed to domestic animals is clearly 

 presented in a letter which I recently received 

 from Professor Willard, of the Kansas Agri- 

 cultural College, who has had a wide experi- 

 ence with practical feeding experiments made 

 on a large scale on domestic animals. He 

 says: 



It is a matter of common experience extending 

 over many years, that corn appears to be deficient 

 in some particular in nutritive value. Some have 

 thought to account for this on the basis of low 

 protein content; others have attributed the result 

 to its small percentage of ash; still others have 

 taken into account not only the small percentage 

 of ash, but its unbalanced character, being defi- 

 cient in calcium and possessing a large percentage 

 of magnesium; still more recently there has ap- 

 peared the possibility that the defect may find an 



' Read before the National Academy, November 

 13, 1912. 



explanation in limitations in the amino-acid com- 

 ponents present in the corn protein. 



From this quotation it is evident that 

 further study is needed in respect to the rela- 

 tive nutritive value of the constituents of this 

 seed. Professor Mendel and I have recently 

 obtained preliminary results from feeding 

 maize proteins to white rats under conditions 

 similar to those which I described at our fall 

 meeting last year. 



The proteins of maize have not received the 

 attention that their great economic impor- 

 tance demands, for these, the most valuable 

 constituents of this seed, form from eight to 

 ten per cent, of a crop which in this country 

 alone is annually worth one and a half bil- 

 lion dollars. This is the more remarkable as 

 those chemical investigations which have been 

 made show that at least one half of the protein 

 of this seed consists of a type possessing such 

 unique chemical and physical characters as to 

 make it probable that its nutritive properties 

 diifer to a marked extent from those of the 

 proteins in other foods of either vegetable or 

 animal origin. 



In addition to this protein, known as zein, 

 the maize kernel contains small quantities of 

 globulins, albumins and proteoses and also 

 protein substance insoluble in neutral solvents 

 which can be extracted from this seed only by 

 dilute alkalies. This latter protein has been 

 named maize glutelin. According to such 

 data as are at present available, zein forms 

 about 58 per cent, of the proteins of corn, the 

 globulins, albumins, and proteoses together 

 about 6 per cent., and the remaining 36 per 

 cent, is supposed to be maize glutelin. 



The few recorded attempts to determine the 

 nutritive value of maize proteins, in the iso- 

 lated state, have been made only with zein. 

 The conditions under which these have been 

 conducted have been such as to render the re- 

 sults of uncertain value, although in every in- 

 stance zein, when supplied as the only pro- 

 tein, proved ineffective for maintaining adult 

 animals or promoting the growth of the young. 



Zein presents striking differences in its 

 amino-acid make-up when compared with the 

 other proteins commonly present in foods. 

 The greatest interest has centered about the 



