Apr. 10, 1916 



Citrus Canker 



91 



Cellulose determinations in fraction 3 were made in duplicate with 

 accordant results by employing Schweitzer's reagent in one case and a 

 solution of zinc chlorid in hydrochloric acid in the other. 



Polysaccharids in fraction 3 were estimated as dextrose after 2.5 hours' 

 hydrolysis in a reflux condenser using 2.5 per cent hydrochloric acid. 



In Table II are given the fresh weights of normal and cankerous Citrus 

 tissue, moisture content, dry weight, and alcohol-ether soluble and in- 

 soluble portions. 



Table II. — Analysis of normal and cankerous tissue of grapefruit leaves 



Item. 



Nonnal tissue. 



Cankerous 

 tissue. 



Fresh weight 



Moisture 



Dry weight 



Total alcohol-ether 



Soluble 



Insoluble 



Gm. 

 27. 250 

 16. 799 

 10. 451 



4.270 



6. 181 



Gm. 



27.250 

 16. 796 

 10. 454 



4.300 

 6. 154 



In this composite table it is strikingly significant that only slight 

 differences are apparent. The moisture content of normal tissue is 

 slightly greater than that of cankerous tissue, and there is, of course, a 

 corresponding decrease in dry weight. The greater amount of alcohol- 

 ether soluble material occurs in cankerous tissues with a lesser amount of 

 alcohol-ether insoluble substance. The differences represented herein 

 would have little or no value in themselves if it were not that they were 

 obtained by the use of a refined method of analysis primarily intended to 

 permit the discovery of changes not indicated by ordinary methods. 

 Studies of the intricate relation of parasite and host have proceeded far 

 enough to indicate that large changes in composition of the host are not 

 to be expected, but rather that transformations have been produced 

 which, though minute in amount, profoundly affect the metabolism of 

 both parasite and host. Table III gives in detail the results of the 

 several steps in this analytical procedure. 



Table III. — Analyses (in grams) of normal and cankerous grapefruit leaves 



27470°— 16- 



