Part II. 



PREFATORY NOTES. 



VARIOUS FEATURES OF THE RESEARCH. 



The routine laboratory studies included in Part II were made, as stated in 

 the Introduction (page 14), by Dr. Elizabeth E. Clark and Miss Martha Bunting. 

 The former carried out all of the observations herein recorded except those of a 

 group comprising Vicia, Lathyrus, Quercus, Castanea, lAlium, Tulipa, Convallaria, 

 Amaryllis, Crinum, Sprekelia, Hcemanthus, Hymenocallis, Leucoium, Crocus, Spar- 

 axis, Curcuma, Maranta, and Zamia, together with the temperature reactions. Miss 

 Bunting made all of the studies included in this group as weU as the important 

 determinations of the temperatures of gelatinization. 



The methods employed in this research are described in Chapter VI (page 295), 

 in which portion of the memoir is also explained the scheme of construction of the 

 Curves of Reaction-Intensities, which constitute a very important feature of this 

 part of the report. Additional charts of a different character, which show compara- 

 tively the reaction-intensities of all of the starches studied with each agent, a table 

 of the temperatures of gelatinization of all of the starches, and also statements 

 relating to the comparative values and individual peculiarities and certain other 

 matters pertaining to these methods, will be found in Chapter VII (page 303). 



According to the literature available at the inception of this investigation it 

 seemed questionable as to what data of value in indicating stereochemic dififerences 

 in different starches, different starch-grains, and parts of grains were to be gained 

 by such gross histological investigations as were recorded especially by Fritzsche, 

 Schleiden, and Nageli, and by such refined methods as those pursued by Kraemer, 

 Denniston, and others. The gross histological properties of starches have been 

 shown to be so readily affected by various incidental conditions that starches 

 from genera of a given family (as now constituted by the data of the systematic 

 botanist) may have very unlike gross histological features, while on the other 

 hand those from genera without the remotest relationship may be so much 

 alike microscopically as to lead to the belief that they had a common plant-origin. 

 While it seemed probable that the refined methods by which the minute structure 

 of the starch-grain is analyzed would elicit data of importance in correlating histo- 

 logical and stereochemic relationships, it seemed equally likely that they would 

 not in general yield results so valuable, on the whole, as could be obtained by other 



