1902] THE STRUCTURE OF THE STARCH GRAIN 353 



founded. Furthermore, this appearance (crystalloidal) might 

 be considered as due to an internal folding of the substance of 

 the lamellae, but this would only arise in case of a contraction 

 or reduction in the area of the lamellae ; but as we have already 

 seen the grain is swollen from two to four times its original size, 

 and even in the fragments of the disintegrating grains th^ crys- 

 talloidal character is pronounced. It seems more likely, as I 

 have already pointed out, that the reason this structure is not 

 apparent under natural conditions is because the refractive 

 properties of the crystalloidal substance so nearly resembles 

 that of the associated colloid. The use of certain reagents, 

 however, which are more or less penetrating in their action, 

 cause an imbibition of water by the colloidal portions with con- 

 sequent swelling of the grain, and hence a contrast in refractive 

 power with the more insoluble crystalloidal substances. 



College of Pharmacy, 



Philadelphia. 



LITERATURE CITED. 



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1851. 



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