Form of Hormidium flaccidum , A. Braun . 535 
stocked with this substance, but absorbed the greater part of it during the 
first week of desiccation before the production of granules became apparent. 
Hence, possibly, the latter were small and sparse when they eventually 
appeared. In both experiments, as desiccation proceeded, the substance 
in question gradually diminished in amount, and had become exceedingly 
scanty by the time the granules attained their maximum abundance. This 
stands in contrast to the accumulation which occurred, simultaneously with 
the production of granules, in well-nourished cells receiving abundant water- 
supply. 
It may be that in reality both ample nutrition and desiccation cause 
a concentration of this substance, which results in the formation of granules. 
This view receives some confirmation from the fact that small granules can 
be produced in cells in the right condition, by gradually withdrawing water 
Fig. 6. A, cell in which the special substance stained by Sharlach R (cf. p. 532) is distributed 
as fine drops in the surface of the protoplasm. B, accumulation of the same substance in the 
vacuoles, c, ditto, the stained substance appearing partly in the form of large drops, d, small 
granules produced in a previously clear cell on the withdrawal of water from it by means of weak 
glycerine, s., substance stained by Sharlach R; other lettering as in Fig. 1. (All figures x 2000.) 
from them by means of weak solutions of glycerine, sugar, or salt (Fig. 6 , D). 
It is possible that this substance is one of the primary products of photo- 
synthesis, while the granules constitute a secondary, reserve product. 
A considerable interest centres round the relation between the production 
of starch and granules, since the granules also appear to be a reserve food. 
As a general rule, starch is scanty in cells poor in granules, and abundant in 
densely granular cells, so that both substances appear to accumulate under 
the same circumstances. For example, there was very little starch present 
in the material of the first desiccation experiment, but a great deal in 
many cells of the second desiccation experiment (see Tables I and II). 
Starch was abundant in the material cultivated in glucose solutions (cf. p. 531) 
and in the damp greenhouse material referred to above (p. 525). Nevertheless, 
