T r II e , Notes oii the Phy siologj' of the Sporophy te etc. 39 



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of tlie directive influence of lateral illumination and the absence 

 of uniformity in Symmetrie illumination, that the radius in which 

 the sporophyte falls in carrying out this cm-vature is determined 

 by the direction of the strongest illumination. 



In the hope of getting further light on the question, seve- 

 ral attempts were made to carry through to maturity cultures 

 in a horizontal position on the klinostat, but unfortunately I was 

 balked each time by the occasional failure of the apparatus to 

 perform its duty. In spite of these discouraging features, a pot 

 of Mniiim capsules was obtained in which, instead of the usual 

 pendulous position, an average inclination of 30 ^ from the per- 

 pendicular was seen at maturity. 



Experiments with Funana gave results very similar to those 

 above described. The Funaria sporophytes shoAved themselves 

 more quickly responsive to lateral illumination than Mnium. An 

 unknown species of Wehrra, found on a somewhat exposed hill- 

 side. was more sensitive to the directive influence of light than 

 eitlier Funaria or Mnium. 



In view of the partial failm-e of the klinostat experiments, 

 it was deemed desirable to Supplement the observations descri- 

 bed with some further evidence to show the relative effective- 

 ness of light and gravity in calling forth responses in the spo- 

 rophyte. and the following stndies were made in the s})ring of 

 1901, ad Harvard University. 



Two experiments were carried out with Mnium cus-pidatum^ 

 a form found in great abundance in the open woods near Ar- 

 lington Heights. Colonies of this moss were transplanted March 

 22 with the least possidisturbance to flower pots filled with wood- 

 soil and taken to the greenhouse laboratory at the Botanical 

 Garden. The sporophytes had already made considerable pro- 

 gress but were still erect and showed no indication of a capsular 

 enlargement. 



In the first experiment, the desire was to ascertain the be- 

 haviour of the growing sj)orophytes when ])laced in a horizontal 

 position with ])erpendicuhir illumination. These conditions were 

 obtained by sinking the pot containing the Mnium c-ulture on 

 its side in a larger pot filled with sphagnum which was held 

 away from the plants by another flower |)ot placed with its 

 mouth over the open end of that containing the moss. Light 

 was admitted by breaking out a piece of the empty pot 1 inch 

 wide by about 3 — 12 inches long. After placing the moss tuft 

 in the position described, the containing pot was i)ut in bright 

 diffusecl light. After forty-eight hours, nearly all of the sporo- 

 phytes had made a more or less marked curvature upwards to- 

 ward the light. This curvature was some distance from the free 

 end of the sporophyte and seemed to be clearly located in its 

 growing zone. Another curvature much sharper and more loca- 

 lized was also noted, especially in the more advanced individuals, 



