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AMERICAN ' 
JOURNAL OF BOTANY 
Vol. Ill March, 1916 No. 3 
THE SPECIFICITY OF PROTEINS AND CARBOHYDRATES 
IN RELATION TO GENERA, SPECIES AND 
VARIETIES* 
Edward Tyson Reichert 
It has long been known that both animals and plants can be 
definitely grouped upon the basis of the presence or absence of some 
particular kind of substance or group of allied substances, etc.: 
animals, in accordance with the presence or absence of haemoglobin, 
haemocyanin or myogen, etc.; and plants as to whether or not they 
contain starch, glycogen, tannic acid, some peculiar forms of toxic 
substances or some particular form of protein, etc. As regards pro- 
teins, it has been found that proteins of seeds from different plant 
sources are not identical and that similar or apparently identical 
proteins are found only in seeds that are botanically closely related. 
From the results of a series of elaborate investigations that are being 
carried on under the auspices of the Carnegie Institution of Washington 
we may go farther than this gross differentiation of groups end state 
that a given substance such as haemoglobin or starch may exist in 
modified forms which in number may infinitely exceed the number of 
known genera, species and varieties, and that from present indications 
these modifications are specifically taxonomic. 
In order to have clear conceptions of the possibilities of such 
inconceivably numerous forms of a single substance it is essential 
that we recall to mind certain salient facts regarding modern concep- 
tions of molecular structure. It will be remembered that when 
substances have the same kinds and the same number of each kind of 
atoms they are isomers, and have the same molecular formula; that if 
isomers so differ in their properties as to indicate that they are different 
* Invitation paper read before the Botanical Society of America and affiliated 
societies at Columbus, December 29, 1915. 
[The Journal for February (3: 45-90) was issued March 4, 1916]. 
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