276 BOTANICAL GAZETTE [APRIL 
Starch occurs in the endosperm of seeds of Rumex crispus and 
Daucus Carota. It does not occur in the embryo of any seeds under 
investigation. Moreover, the hydrogen ion concentration is not 
likely to be materially changed by such hydrolysis of starch as 
may occur during their germination, and therefore we need not 
consider starch an important factor in their germination. Since 
suberin is found in the coats of Oenothera biennis and Daucus 
Carota, but not elsewhere, it can hardly be considered a common 
limiting factor in the germination of the light-sensitive seeds 
studied. Oily or fatty substances were found in the cell contents 
of coats, endosperms, and embryos of each of the seeds, appearing 
as small droplets of substance readily stained with Soudan III or 
Scharlach R. These lipoids almost never occurred as continuous 
layers which might obstruct the entrance of water or other substance 
necessary for germination, but usually as emulsions of fats in the 
cellsap. The results of the experiments on the absorption of water 
support the observation that there is no important obstruction of 
water by the constituents of the coats. Hence suberin and lipoids 
need no further consideration as limiting factors in absorption of 
water by these seeds. 
Using neutral red as an indicator, seeds soaked in water in 
light and in darkness, as well as dry seeds, were tested for the 
reaction of the different parts with results shown in table XVII. 
The outstanding result of the microchemical- examination is 
the greater acidity of seeds incubated in light as compared with 
those incubated in darkness. This was found to be the case in each 
of the five kinds of light-sensitive seeds. The embryos incubated 
in light had a higher hydrogen ion concentration than those of the 
same kind incubated in darkness. This was especially noticeable 
in the hypocotyls. This result is contrary to HEINRICHER’S (21) 
unsupported assumpton that the effectiveness of the fat splitting 
lipase was favored by the increased acid formation in darkness in 
Phacelia tanacetifolia. Moreover, HEINRICHER offered no experi- 
mental evidence of increased acid formation i in darkness. Having all 
known external factors, except tion, alike for the seeds under 
investigation, we may properly conclude that the varying factor, 
light, in some way brings about increased acidity of their embryos. 
