GENUS MANIHOT. 877 



With safranin the grains begin to stain immediately and at the end of 25 minutes tlie normal 

 grains are deeply stained. This reaction is much greater than with gentian violet. 



Temperature Reaclion. The temperature of gelatinization is 61 to 63 C, mean 62. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in 2 minutes in the 

 ungelatinized grains and is over in 25 minutes. It is the same qualitatively as that of the grains of 

 the nearly related genus Jalropha aircas. 



The reaction with chromic acid begins in 15 seconds and is over in 2 minutes. It is qualitatively 

 the same as that of the grains of Jatropha curcas. 



Reaction with pyrogallic acid begins in 15 seconds and is over in 3 minutes. It is qualitatively 

 the same as that of the grains of J. curcas. 



Reaction with /er?'ic chloride begins in some grains in 30 to 60 seconds and is over in 18 minutes. 

 It is qualitatively the same as that of the grains of J. curcas. 



With Purdy's solution reaction begins in 13-^ minutes and consists in the rapid, complete gelat- 

 inization of those grains already partially gelatinous and in a slight enlargement of the hilum in 

 the uninjured grains. After this initial reaction there is no further change. 



NOTES ON THE STARCHES OF EUPHORBIACEiE. 



The starches of Jatropha and Manihot bear close histological resemblances, exhibiting only 

 minor differences in the characters of the hilum and lamelliE. In their reactions they show marked 

 differences in most instances. Jatropha has a lower degree of polarization, higher sensitivity to iodine 

 and gentian violet, lower sensitivity to safranin, lower temperature of gelatinization, and greater 

 sensitivity to all of the chemical reagents. 



