PREFACE. 



related or allied species or genera. Since Magendi 

 in 1839 found that when egg albumin is injected into 

 rabbits the animals become so sensitized that death 

 is caused by a second injection, an enormous amount 

 of work has been done in similar and allied experi- 

 ments. The literature that has . accumulated is so 

 exceedingly voluminous and of such a character that 

 even a review of the most important of the investi- 

 gations is quite impossible within the allotted limits 

 of space of this report. But there are several re- 

 searches that have appeared since the publication 

 of the preceding memoirs which, like the foregoing, 

 are of such especial importance in connection with 

 the present investigations that*they, as in the case 

 of several others above referred to, should receive at 

 least a passing notice. For instance, Bradley and 

 Sansun (Jour. Biolog. Chem,, 1914, xvm, 497) 

 found that guinea pigs that are sensitized to beef 

 or dog hemoglobin, fail to react, or react only slightly, 

 to hemoglobins of other origins. They tried the hemo- 

 globins of the dog, beef, cat, rabbit, rat, turtle, pig, 

 horse, calf, goat, sheep, pigeon, and chicken, and of 

 man, and they found reasons 'for the conclusion that 

 the hemoglobins from different sources are chemically 

 different. 



The studies of Wells and of Wells and Osborne of 

 the biological reactions of vegetable proteins (Jour. 

 Infect Dis., 1911, vm, 66; 1913, xn, 341; 1914, 

 xiv, 377 ; 1915, xvn, 259 ; and 1916, xix, 183) show 

 among various findings of variable degrees of im- 

 portance that chemically similar proteins from the 

 seeds of different genera react anaphylactically with 

 one another, while chemically dissimilar proteins 

 from the same seeds in many cases fail to do so. 

 Blakeslee and Gortner (Carnegie Institution of 

 Washington Year-Book, No. 12, 1913, 99) record evi- 

 dence in their investigations of the precipitin reactions 

 of the proteins of mold that is consistent with the con- 

 clusion that there are not only "species proteins" but 

 also "sex proteins" (see Chapter vi, pages 366 and 

 367) ; and Gohlke and Mez, and Lange (Umschau, 

 1914; Scientific Amer. Sup. 1914, No. 2016, 122) 

 have recorded most significant data in the determina- 

 tion of plant relationships by means of sero-diagnosis. 

 Taxonomic relationships of a number of families were 

 studied and references are also made by Gohlke to 

 the differentiations of plant albumins by Kowarski 

 and to the experiments of Magnus and Friedenthal 

 which showed a relationship between truffles and yeast. 

 Legrand (Revue Generale des Sciences, 1918; Scien- 

 tific American Supplement, 1918, No. 2238, 322) 

 has brought together a large number of diversified 

 facts in support of zoologic biochomic specificities. 



Comparing the results of the various "biologic 

 tests" with those recorded by means of the methods 

 used in the starch and hemoglobin researches, it seems 

 to be conclusively demonstrated, as far as these 

 investigations have gone, that the latter are capable of 

 practically unlimited development by addition and 

 improvement. The studies of the starches and hemo- 

 globins are not more than merely started, and there 

 remain virtually untouched (for exceptionally invit- 

 ing and extensive investigation) albumins, globulins, 

 proteoses, glycogens, fats, cholesterols, alkaloids, en- 

 zymes, hormones, and a host of other substances that 

 undoubtedly appear in animal and plant life in stereo- 

 isomeric forms that are specifically modified in rela- 

 tion to the protoplasmic source. When one pictures 

 what these three exploratory researches have brought 

 forth and what they suggest as being in part the 

 outcome of further inquiry the imagination becomes 

 bewildered by the marvellous richness of what is thus 

 forecasted. 



The methods used in the preceding research have 

 in the present investigation been extended and so 

 improved as to yield records that are satisfactory in 

 quantity, kind, and accuracy ; and in reference thereto, 

 it seems needless at this juncture to do more than pre- 

 sent certain excerpts from reports by the writer that 

 have appeared in the Year Books of the Carnegie 

 Institution of Washington or elsewhere, as follows: 



" The investigations with the starches were neces- 

 sarily carried on by methods that are quite different 

 from those employed in the study of the hemoglobins. 

 Although the starch granule is a spherocrystal that lends 

 itself to crystallographic study, very little can be learned 

 of its molecular characters that is of usefulness in the 

 differentiation of various starches. Other methods, how- 

 ever, offer very satisfactory means of study, especially 

 those which elicit molecular differences by means of 

 peculiarities of gelatinization. These methods, all micro- 

 scopic, have included inquiries into histological charac- 

 ters; polariscopic, iodine, and aniline reactions; tem- 

 peratures of gelatinization ; and quantitative and quali- 

 tative gelatinization reactions with a variety of chemical 

 reagents which represent a wide range of difference in 

 molecular composition. 



" Each starch property, whether it be manifested in 

 peculiarities in size, form, hilum, lamellation or fissura- 

 tion, or in reactions with light, or in color reactions with 

 iodine or anilines, or in gelatinization reactions with 

 heat or chemical reagents, is an expression of an inde- 

 pendent physico-chemical unit-character that is an index 

 of specific peculiarities of intramolecular configuration, 

 the sum of which is in turn an index which expresses 

 specific peculiarities of the constitution of the proto- 

 plasm that synthetized the starch molecule. The unit- 

 character represented by the form of the starch grain is 

 independent of that of size ; that of lamellation independ- 

 ent of that of fissuration, etc. This is evident in the 

 fact that in different starches variations in one may not 



