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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
ceeds, — this gemma-scale arises upon the upper side of the thal- 
lus, especially upon shoots which hear neither sexual organs nor 
receptacles for gemmas. These gemma-scales require investiga- 
tion especially in their biological relationships.” No trace of 
these scalelike appendages showed on the dorsal surface of the 
specimens studied. In only one case were the gemmae found 
germinating in the flask, and in this instance only a single 
protuberance was pushed out at the side. This flask was an old 
thallus and the gemmae probably had been developed the fall 
before. This is an exception to the usual procedure, however, 
for the gemmae are expelled at maturity, while young buds are 
forming at the base of the flask. Conditions for germination are 
not likely to be favorable when the biood-buds are tightly 
crowded together in the flask and surrounded by the viscid gel- 
atinous substance produced by the mucilage papillae. 
When gemmae are placed in a favorable situation, growth pro- 
ceeds by means of the end cell which develops into the regular 
wedge-shaped apical cell already described for this plant. In 
the earlier stages of the thallus, the apical cell builds up a 
broad flat stem and the leaf-like lobes appear on opposite sides 
of this expanded portion. In very early stages the plant looks 
like a leafy liverwort having distinctly separated lobes set on 
the stemlike midrib apparently like leaves. The lobes must in- 
crease in bulk laterally for in the mature thallus they are closely 
set together forming a more nearly thalloid plant. At the apex 
of the young plant, the lobes form a rosette around the growing 
point. This arrangement is advantageous, as it affords protec- 
tion for the bud. 
Nostoc appears in the plant very soon after the gemmae ger- 
minate. Often two or three distinct colonies may be formed on 
plants .25 mm. in length. It is possible that the Nostoc finds en- 
trance into the flask and adheres to the gemmae before they are 
shed. Rhizoids develop early on these little plants and soon be- 
come long and much entangled. 
It would seem that the young plants could not long thrive 
perched on the dorsal surface of the thallus but they do grow for 
a time, probably upon nourishment stored in the gemma which 
persists at the base of each new plant. As the old thalli die 
these new shoots are allowed to rest on the soil where they ma- 
ture into vigorous well-developed plants. Further study will 
