Tr ue, Notes on the Physiology of the Sporophyte etc. 
41 
In tlie second experiment, an attempt was made to make 
this clear. O 11 March. 27, a healthy culture of Mnimn cuspida- 
tum was potted and packed as above described and placed with 
tlie sporophytes in a horizontal position. Illumination front be- 
low was secured by means of a mirror placed ab out 8 inches. 
below the culture which reflected light from the eastern sky 
upon the horizontal sporophytes. Light was admitted through 
an opening 1 — 1 4 inches wide and 2 inches long, made by bre- 
aking a place in the pot opposite the sporophytes. Except in 
the forenoon. when some direct sunliglit was reflected upon the 
plants, strong diffused light was supplied. 
On March 29, the young sporophytes in many cases showed 
a sliglit gradual bend in the distal half in an upward direction. 
in a raanner not markedly different from that seen in the pre- 
ceding experiment. At the distal end a slight downward direc¬ 
tion is noticeable, brought about by a curvature of smaller ra- 
dius near the lower edge of the calvptra. In a few cases, the 
sporophytes were practically horizontal except at the distal end, 
where a downward curve was seen. 
On April 1, no increased curvature in the setal was noticed. 
A sharp downward curvature at the lower edge of the calvptra, 
however. was conspicuous, bringing the now clearly enlarged 
capsular rudiments into a position approaching the perpendicu- 
lar. A ith but three exceptions in about thirty-five individuals, 
the tips of the calyptrae pointed ahno'st directly downwards, 
therefore. against the incident light’ rays. 
On April 10, the capsules were found to have developed 
normallv and were approaching their full size. In every case, 
the long axis of the capsule was perpendicularly directed, and 
stood at approximately a right angle to the axis of the seta. 
The plants seemed to be entirely healthy. 
The experiments above described seem to make it clear that 
in the case of Mnium , and probably of Funaria also, the „nod- 
ding" of the capsules is brought about by the stimulating ac- 
tion of gravity, since the direction of the Illumination does not 
interfere with the tendency of the capsules to assume the ,,nod- 
ding kC or, in the case of Mnium, the pendulous position, seen in 
na time. The partial success of the klinostat experiments points 
in the same direction. 
The directive inhuence of illumination is clearly marked in 
determmmg the plane in which the capsular rudiment shall fall. 
Sometimes the apex of the capsttle falls toward the source of 
light, sometimes a'gainst it. This conclusion has been tested many 
times by the study of Mnium in its usual habitat. and, with 
very rare exceptions. it is possible to parallel the results seen in 
the laboratory. Occasional exceptions may be accounted for by 
considering the foliage conditions and tlie position of the sun 
in the lieavens during the day at the time of the year when 
the sporophytes are developing. Yarious obstacles interfering 
with light may thus be located. 
