30 T r II e, Notes on tlie Physiologj- of the Spon.j)li\ie etc. ^ 



were ineasured from time to time. Since, even wlien carefully 

 carried out, the sinall size of the objects under study and tlie 

 interference by the calyptra stood in the way of the highest 

 at'curacy, only an approxiniation to tlie truo relations was ob- 

 tained. ' I believe, however, that the chicf featurcs of the rate 

 and tlie distribution of growth were distinctiy to be seen. No 

 attenipt was niade to ascertain the growth rate in the stages 

 prior to the emergence of the tip of the archegoniuni froin 

 among the porichaetical leaves. 



Measurements initiated as soon as the appearance of the 

 growing archegoniuni above the perichaetiuni would permit iri- 

 dicated that the growth rate was very slow, about 0,13 mm. in 

 twenty-four hom-s in a temperature ranging between 20 ^ C. and 

 25 ° C. Perhaps this slowness was in part due to the restraining 

 action of the archegoniuni which was still attached to the ga- 

 metophyte and probalily not keeping pace in growth rate with 

 the included sporophyte. 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. \Vhen the edge of the ca- 

 lyptra presented itself above the pericliaetium, the growth rate 

 seen to have risen from 0,2 to to 2,0 2,5 mm in twenty-four liours. 

 Subsequent measuremeuts showed that this rate of elongation 

 was slowly and steadily increased until the sporophytes reached 

 a total length of from 10 to 12 mm, the stage preceding th(^ 

 fir.st indication of the curvature. As the curvature became more 

 pronounced, the growth rate feil off rapidly, and when, in about 

 forty-eight liours, the rudimentary capsule became distinguis- 

 hable, growth of the seta sank to iiearly zero and, as the gro- 

 wing capsule became increasiiigly prominent, soon ceased alto- 

 gether. The growth made cluring this period of declining elon- 

 gation in the seta was unequall}^ distributed and, being more 

 rapid on the convex side of the seta, served to bring about the 

 curvatm-e noted. That this curvature was a permanent feature 

 connected with growth, rather tlian a result of unequal turgor 

 pressure, appeared on j^lacing the young sporophytes in plasmo- 

 lizing Solutions. No clianges 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 inany other plant 

 structures that have been studied. The regularity of the ascent 

 durin o- the eaiiier stag-es it somewhat interefered with by the 

 inechanical restraint prior to the breakiiig aw^ay of the arche- 

 gonium from the gametophyte. The elongation of the seta is 

 completed in about ten 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 



