410 BOTANICAL GAZETTE [ May 
approach the limit of visibility, since the trichites are, according to ieyer, 
so slender as to approach this limit. This is, of course, an absurd assump- 
tion. Fischer shows also that the storing of colors is difficult or impossible 
to explain on the crystal-trichite theory. It is well known, however, that col- 
loids and even liquids (e. g., clove oil) are able to store up coloring matter, 
but no crystals are known which do this. Moreover, starch and inulin which 
have been stained while wet and then air-dried cannot be decolorized by 
alcohol or clove oil. It is impossible to understand why alcohol cannot pene- 
trate between the trichites and withdraw the coloring matter, since, even, in 
the air-dry condition, there is still 20 per cent. of water around the trichites. 
The relations of starch to iodine, also, are difficult to explain on Meyer's 
theory. Only when wet does starch give the well-known blue reaction with 
iodine; dry grains react brown. When blue grains are air-dried they become 
brown. To explain this upon the crystal theory would require us to assume 
that when the trichites are surrounded by a little water the iodine solution is 
brown, but when the crystals are surrounded by a larger quantity of water it 
is blue ; again, an impossible assumption. 
Fischer also criticises Biitschli’s theory of “foam” structure for bodies 
capable of swelling, in which an attempt is made to explain the force devel- 
oped by imbibition by osmotic action of the substance occupying the “ bubble” 
spaces. His own view, stated very briefly, is that both in starch and inulin 
a true chemical relation exists between water and the molecules of amylose 
and inulin, in consequence of which the molecular structure is different 
according as greater or less quantities of water are present, after the analogy 
of some crystals. Watery amylose and inulin have different physical was 
erties from those they possess when air-dry. Only in the watery condition 
can they dissolve in their own substance and store certain coloring matters ; 
others are insoluble. Iodine, whose tints differ according to the solvent, !s 
dissolved in watery amylose with a blue tint. When air-dry the iodine is not 
in solution, but is distributed through the amylose in fine solid particles. 
Swelling, Fischer holds, is thus a purely molecular process —a loose com 
bination of molecules with water after the fashion of water of erystalliza- 
tion in some salts. Upon an increase of water this condition passes without 
break into the state known as solution, that is, a still looser relation of the 
molecules to water. The fact that imbibition occurs for inulin, starch, ane 
lose, gums, gelatin, etc. only with water, supports this view. The heen 
Structure of both starch and inulin spherites is explicable as due to radia 
cracking. These cracks are exceedingly minute in starch and into them ~ 
air does not enter. They are larger in inulin spherites and are penetrated by 
air. The double refraction of both bodies is due to the strains under sie 
the masses exist; strains which are not completely relieved in ee 
the expansion due to true imbibition has passed over into the semi-solution © 
the gelatinous state. Both inulin and starch grains are thus considered to be 
