1902] THE STRUCTURE OF THE STARCH GRAIN 345 



crystalloidal substances, namely starch cellulose^ and granuloses 

 and also a colloidal substance. These occur as followis: i^a) In 

 the point of origin of growth we find the colloidal substance 

 associated with a small proportion of cellulose as also in the 

 alternate lamellae ; (^) in the other layers occurs the granulose 

 associated with a small amount of colloidal substance and pos- 

 sibly also some cellulose; (<r) the peripheral layer of the grain is 

 not readily acted upon by reagents and is quite elastic and 

 more or less porous, probably consisting of an anhydride of 

 cellulose ; (^) in some cases some of the dextrins or some of the 

 non-colloidal or crystalline carbohydrates, as maltose, dextrose, 

 levulose, etc., may be present, but these are probably formed as 

 a result of alterations taking place in the grain. 



There have been a number of important contributions on the 

 subject of the origin and structure of the starch grain, and while 

 the views of the authors appear to be more or less at variance, 

 still this is not to be wondered at, and it is highl}^ probable that 

 future observations will harmonize some of these conflictinsf 



views. 



The illustrations of potato starch grains in the different text- 

 books show two kinds of grains, one in which the point of the 

 origin of growth and alternate lamellae are light in color, as 

 figured by Sachs (26) ; and the other in which the corresponding 

 parts are dark in color, as figured by Strasburger (27). There 

 is in reality no difference in these grains, this apparent difference 

 being due to the manner of focusing upon them {figs. 1,2), that 

 is, whether viewing the lamellae from above or from below, or, 

 as the Germans would say, by *'tiefe oder hohe Einstellung." 

 The two views of the successive lamellae thus obtained may be 

 compared to the appearances obtained with two entirely different 

 substances, the one corresponding to a more or less definite solid 

 substance, as an oil globule, and the other to a body such as an 



air 



babble (or vesicle filled with air or any other gaseous or 



3 Cellulose was a terra first applied byXageli (16) and corresponds to the farninose 

 of Von Mohl (20) and probably to the ^S-amylose of Arthur Meyer (21). Granulose 

 another term which is generally accepted to have been coined by Nageli (16), was 

 adopted by Von Mohl (20) and apparently corresponds to the a-amylose of Arthur^ 

 Meyer (21). 



