668 Wisconsin Academy of Sciences , Arts, and Letters. 
Strasburger (38, p. 147) considered the weakly refracting 
layers as limiting lines or adhesion surfaces between lamellar 
complexes. Meyer (18, p. 107), holdiiig that the grains are 
composed of crystalline units, explained the light and dark 
layers by the assumption that where there are many and large 
pore canals between the trichites the layers are loose, and that 
where the trichites a.re more closely packed the layers are dense. 
He observed also that, when grains are dried at 20° C over 
sulphuric acid in a vacuum, scarcely a trace of lamination re¬ 
mains. 
Suiter (32, p. 6) found that the starch grains show alter¬ 
nate light and dark blue layers with E lemming’s triple stain. 
He concluded, since the aniline dyes are so easily removed from 
the stained starch grains, that staining is merely a process of 
imbibition of the coloring matter between the particles of 
starch substance. The layers taking the dark violet stain he 
supposes to be loose and watery, the less refractive layers of 
the unstained grain. 
Meyer (18, p. 149) stained with methyl violet and then ap¬ 
plied a very dilute solution of calcium nitrate, with the re¬ 
sult that a large part of the stain was precipitated as a gran¬ 
ular mass in what he holds to be the loose layers. Neither 
Meyer nor Salter furnished satisfactory evidence as to whether 
it is the dark or light layers of the unstained grain which take 
the deepest color in staining. 
Eischer (7, p. 81) carried these precipitation experiments 
somewhat further by using picric acid as a precipitant instead 
of calcium nitrate. He allowed a drop of the dilute aqueous 
stain to dry on the section, then added a few drops of picric 
acid solution and washed with water. He found that the fol¬ 
lowing stains were not at all taken up by the grain: nigrosin, 
Hessian purple, diamond red, carmin, anilin blue, cyanin and 
Congo red. The following gave a uniform coloration of the 
starch substance: acid fuchsin, corallin, eosin, crooein, tropae- 
olin, Martin’s yellow and haematoxylin. The following gave 
fine-grained precipitates in the watery zones: fushsin, safranin, 
methyl blue, methylen blue, indigo carmin, indulin, methyl 
violet and gentian violet; the latter in the form of large crys- 
