True, Notes on the Physiologe' of the Sporophyte etc. 35 



Experimental. 



I liave given attention especially to the development of the 

 sporopliyte of two of our commoner species, Funaria hygrome- 

 trica Sibth.. cliaracteristically found in expo.«ed. snnny spots, and 

 Mniiim ciispidaiurn Hedw., one of the .shade-loving mosses of the 

 woods. In its mature form, the capsule oi Funaria is bilaterally 

 symmetrical and deeidedly arcuate, being convex in its upper 

 outHne, concave beneath. In addition to this ciirvature of the 

 capsule, the seta shows a very pronounced bend some distance 

 below the capsule. The capsule of Mnium cn.spidatum is nearly 

 radially symmetrical and takes a pendant position by means 

 of a sharp curvature of the seta formed very the capsule. 



Early in April, turfs of both species were transplanted into 

 pots and removed to the laboratory for study. The general 

 course of development is much the same in both sjjecies. Fol- 

 lowing the fertilization of the Qg§,i both the archegonium and 

 the young sporophyte begin growth, the latter as a slender body 

 enclosed in the rapidly enlarging archegonium. At this stage 

 the tip of the calyptra may just be seen among the perichaeti- 

 cal leaves. Soon the growth of the archegonium ceases, and this 

 organ is torn away from its attachment by the elongation of 

 the sj)oroph3'te enclosed within it. Goebel (3) suggests that the 

 line at which the archegonium separates from the receptacle is 

 marked by a zone of modiiied, weakened tissues to facilitate the 

 ruptuTe. In a number of instances, specimens of Fiuiaria were 

 seen in which the calyptra failed to separate as usual at the 

 base, and the sporophyte pierced it, growing up through it in a 

 manner recalHng the Hepaticas. This would seem to indicate 

 that occasionally the specialized, weakened zone may still fall to 

 tear with the required readiness. The sporophyte continues to 

 grow in length for about a fortnight under laboratory condi- 

 tions, keeping an erect position. Finally, as the seta reaches 

 nearly the normal length. the curvature begins to appear at the 

 base of the calyptra. Before the curvature of the seta is com- 

 plete, but usually not until it is well under way, the rudimen- 

 tary capsule can be detected as a small sweUing just below the 

 distal extremity of the sporophyte. This structure now enlarges 

 rapidly while growth in the seta rai)i(lly diminishes and soon 

 altogether ceases. The cah'ptra is tinally ruptured by the ex- 

 pansion of the growing capsule and falls away. The capsule of 

 necessity retains permanently the position assumed at the time 

 the narrow, elongating zone below the capsular rudiment loses 

 the power of growth. 



It was tirst necessary to become oriented in regard to the 

 rate and distribution of growth in the sporophyte at the diffe- 

 rent stages of its development. For this purj)ose, Funaria was 

 given most study since it is known to bear hard treatment more 

 easily than many other species. India ink dots were placed at 

 intervals along the sporophytes nnd tho intervening distances 



