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35^ BOTANICAL GAZETTE [November 



of iodine and aniline stains, but also by treatment with water and 

 various reagents as just pointed out. Both Salter and Meyer 

 appear to hold to the theory that there is a distribution of crys- 

 talloidal substance in particular lamellae. Salter quotes Meyer 

 as saying: 'Mie schattierten Schichten bedeuten die schwach 

 lichtbrechenden relativ lockeren, an fester Substanz relativ 

 armen, an Interstitien reichen Schichten, die hellen sind also die 

 stark lichtbrechenden Schichten aufzufassen, welche die meiste 

 feste Substanz enhalten." Here again it is unfortunate that the 

 descriptions do not enable us to determine which layers are 

 meant. It is likely, however, that the layers described as 

 ''schattirten Schichten" are the colloidal layers, and those desig- 

 nated as ** hellen Schichten'' are the crystalloidal layers. 



In summing up the observations herewith presented, we find 

 that the starch grain consists of colloidal and crystalloidal sub- 

 stances, these being arranged for the most part in distinct and 

 separate lamellae, that is, at the point of origin of growth, and 

 in the alternate lamellae the colloidal substance preponderates, 

 associated with the crystalloid cellulose ; whereas in the other 

 layers the crystalloidal substance, consisting for the most part of 

 granulose, occurs in greater proportion. 



As a further evidence of the presence of these crystalloidal 

 and colloidal areas we may say that the peculiar behavior of 

 the colloidal layers toward aniline stains is analogous to the 

 behavior of a section containing mucilage cells toward these 

 dyes, the latter being taken up by the mucilage cells alone. 

 Furthermore, as the characteristics of mucilage cells are most 

 pronounced in anhydrous media, as concentrated glycerin, so a 

 similar effect is observed in the starch grain, but owing to the 

 action of the glycerin in readily forming soluble starch, the 

 preparations of the starch grain, like that of the cell wall, when 

 thus stained are best preserved in Canada balsam. 



The crystalloidal character of certain of the lamellae as 

 observed in connection wjth the swelling of the grain might be 

 considered to be in the nature of microscopic clefts, but it 

 should be said that we know of no colloid that behaves in this 

 manner, and such an assumption does not seem to be well 



:j.r. 



