346 



BOTANICAL GAZETTE 



[NOVEMBER 



rarefied material). The appearance as observed in the oil globule 

 corresponds to that of the layer next to the point of origin of 

 growth and the layers alternating with it. The appearance of 



a 



\ 



Figs. i-io. — Potato starch grains, showing the effect of chromic acid and 



other reagents. 



the air bubble corresponds to that of the point of origin of growth 

 and the layers alternating with it. There is this difference, 

 however, that instead of the purplish hue so characteristic of 

 the air bubble, there is a reddish field in the starch grain which 



that it is of an entirely different 



may 



be taken as indicating 



