36 
True, Notes on the Physiology of tlie Sporopliyte etc. 
were measured from time to time. Since, even when carefully 
carried out, the small size of the objects under study and the 
interference by the calyptra stood in the way of the highest 
accuracy, only an approximation to the true relations was ob- 
tained. I believe, however, that the chief features of the rate 
and the distribution of growth were distinetly to be seen. No 
attempt was made to ascertain the growth rate in the stages 
prior to the emergence of the tip of the archegonium from 
among the perichaetical leaves. 
Measurements initiated as soon as the appearance of the 
growing archegonium above the perichaetium would permit in- 
dicated that the growth rate was very slow, about 0,13 mm. in 
twenty-four hours in a temperature ranging between 20 0 C. and 
25 0 C. Perhaps this slowness was in part due to the restraining 
action of the archegonium wliich was still attaclied to the ga- 
metophyte and probably not keeping pace in growth rate witli 
the included sporopliyte. At all events, as soon as the arche¬ 
gonium was torn loose at its base, a rapid increase in the growth 
rate of the sporphyte was observed. When the edge of the ca¬ 
lyptra presented itself above the perichaetium, the growth rate 
seen to have risen from 0,2 to to 2,0 2,5 mm in twenty-four hours. 
Subsequent measuremeuts showed that this rate of elongation 
was slowly and steadily increased until the sporophytes reached 
a total lengthAof from 10 to 12 mm, the stage preceding the 
first indication of the curvature. As the curvature became more 
pronounced, the growth rate feil off rapidly, and when, in about 
forty-eight hours, the rudimentary capsule became distinguis- 
hable, growth of the seta sank to nearly zero and, as the gro¬ 
wing capsule became increasingly prominent, soon ceased alto- 
gether. The growth made during this period of declining elon¬ 
gation in the seta was unequally distributed and, being more 
rapid on the convex side of the seta, served to bring about the 
curvature noted. That this curvature was a permanent feature 
connected witli growth, rather than a result of unequal turgor 
pressure, appeared on placing the young sporophytes in plasmo- 
lizing Solutions. No changes in form was seen to accompany 
the loss of osmotic pressure. 
Thus the growth curve in its chief features is plainly not 
widely different from that characteristic of rnany other plant 
structures that have been studied. The regularity of the ascent 
during the earlier stages it somewhat interefered witli by the 
mechanical restraint prior to the breaking away of the arche¬ 
gonium from the gametophyte. The elongation of tlie seta is 
completed in about teil days from the appearance of the ca¬ 
lyptra. Experiments were made for the purpose of ascertaining 
the location and extent of the growing zone. By observing the 
movement of the edge of the calyptra from dots placed near it 
on the seta, it soon appeared that the entire zone of elongation 
was situated inside the calyptra, Further experiments showed 
