CHEMICAL VARIATION 



certain factors, chemical methods open up an 

 immensely wide outlook. 



At present chemical investigations into variation 

 and inheritance unfortunately show so many gaps 

 that our report cannot be but a provisional one, 

 and it must rather contain suggestion for fresh 

 experimental work than material already worked 

 out. 



The kinds of variations which morphologists 

 distinguish as' Fluctuating Variation and Mutation 

 are exactly repeated in the chemical properties 

 of living organisms. The Law of Fluctuating 

 Variation discovered by Quetelet is expressed 

 by the statement that the average values are the 

 most frequently recurring ones. The individuals 

 showing a certain characteristic more or less 

 marked, are rarer, the greater the divergence from 

 the average value or average size of the char- 

 acteristic. This law, which can so regularly be 

 shown by measuring the length, weight or volume 

 of an organ of plants or animals in a great number 

 of individuals, supplies exact returns in chemical 

 variations. De Vries gives a report of the result 

 of an examination of 40,000 sugar beets with 

 regard to their content of cane sugar. From the 

 curve given by De Vries we immediately recog- 

 nise the fundamental law. The average quantity 

 of about 16 per cent of sugar was found in nearly 

 7000 beetroots ; 12 per cent sugar in only 340 

 roots, 19 per cent in only 5. It is true that such 

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