1912] GRIGGS—RHODOCH YTRIUM 143 
Almost ideal conditions for observation of the process of starch 
formation are sometimes presented in very young zoosporangia 
(fig. 11), where the cysts are highly vacuolate, with delicate strands 
of cytoplasm stretched from side to side. In thin sections such 
strands are suspended across the cyst, with no adjacent objects to 
interfere with vision. Frequently these strands show all stages in 
starch formation (fig. 11a) from good sized grains down. The 
larger grains are clear cut, sharply outlined against the clear 
cytoplasm in which they are suspended. From such well-formed 
grains there is an unbroken series of smaller and smaller grains 
down to the limit of visibility. The very earliest stages appear as 
mere knots in the cytoplasm, while the definite characters of 
starch grains appear as soon as the body reaches a size large enough 
to be resolvable into an area rather than a point. At no stage was 
anything seen in association with the starch grains except mor- 
phologically undifferentiated cytoplasm. More often, of course, 
the grains are formed in large masses of cytoplasm where the 
opportunities of vision are not so good, but here also they appear 
to lie naked in the cytoplasm. 
The classic examples of the formation of starch grains without 
differentiated plastids were described by STRASBURGER (26, pp. 
155 ff.). He found that in the megaspores of Marsilea and in the 
medullary rays of Pinus the growing grain was invested by numer- 
ous microsomes, which he believed secreted the starch in a manner 
analogous to the formation of the cell wall by the granules of the 
spindle fibers at the close of mitosis. These microsomes were 
large enough to appear as definite granules under a comparatively 
slight magnification (450 diameters). In Rhodochytrium, however, 
no such microsomes could be made out under a magnification seven 
times as great. 
It should be added also that in those stages where starch is 
absent the cytoplasm is smooth and granular, without inclusions 
of any sort. If perchance the writer had overlooked the plastids 
among the grains during starch formation, he would have expected 
to see them here, if present. If there are any plastids, therefore, 
they would appear to be formed de novo rather than carried 
over from generation to generation as permanent organs of the cell. 
