408 CARNEGIE INSTITUTION OF WASHINGTON. 



PHYSIOLOGY. 



Reichert, E. T., University of Pennsylvania, Philadelphia, Pennsylvania. 

 The differentiation of starches of parent-stock and hybrids. (For previous 

 reports sec Year Books 9 to 13.) 



The researches on the differentiation and specificity of corresponding 

 vital substances have for more than a year past been restricted to the 

 study of the starches of parent-stocks and hybrids, studying chieflj' 

 the peculiarities of the starch of each parent and tracing these peculiari- 

 ties to the starch of the offspring. The actual laboratory work has 

 been completed and only the final preparation of the memoir remains 

 to be done, which preparation will be accomphshed, it is hoped, some 

 time during the coming winter. As previously reported, the methods 

 pursued in a preUminary research (Publication No. 173, April 1912) 

 on the differentiation of starches from different sources have been con- 

 siderably extended and improved. Variables which under certain con- 

 ditions may give rise to fallacious results have been to such an extent 

 eliminated that the records obtained in this investigation are as closely 

 in accord as those of carefully conducted determinations of melting- 

 points, and hence practically accurate. The results recorded are in 

 support of those of the preceding researches (Publications Nos. 116 

 and 173) in going to show that complex protoplasmic metabolites are 

 specifically modified in relation to genera, species, varieties, etc., and 

 hence that difference in corresponding substances constitute a specific 

 means of plant and animal differentiation. 



In the studies of starches the histological and polariscopical prop- 

 erties, iodine and aniline reactions, temperatures of gelatinization, and 

 quantitative and qualitative gelatinization reactions with a variety 

 of chemical reagents have been recorded. While these methods of 

 investigation differ widely in character, the results are remarkably 

 harmonious in the demonstration of certain principles of the greatest 

 fundamental importance in normal and abnormal biology. Each 

 property is shown to be an independent physico-chemical character- 

 unit. Hence it follows that while a given property may bj^ one of the 

 means of differentiation appear more developed in the starch of one 

 parent than in the other and be manifested in some degree of inter- 

 mediateness in the hybrid, another property may appear in equal 

 degree of development in the starches of the parents but be developed 

 in the hybrid to same degree or beyond parental extremes in excess or 

 deficit, etc. Each method and each reagent is an independent means 

 of physico-chemical differentiation. Such relationships as are brought 

 out by one may be very different from those elicited b.y another, so 

 that we have as many independent character-units represented as 

 there are methods and reagents. For instance, differences and identi- 

 ties in the processes of gelatinization of the starches of parents and 

 hybrid, and of the hybrids of different crosses of the same parent 

 stock that are not shown by one chemical reagent, may be rendered 



