-6i — 
and probably of Funaria also, the 1 nodding ’ of the capsules is brought 
about by the stimulating action of gravity, since the direction of the illumina- 
tion does not interfere with the tendency of the capsules to assume the 
• nodding,’ or in the case of Mnium, the pendulous position seen in nature.” 
“The directive influence of illumination is clearly marked in determining 
the plane in which the capsular rudiment shall fall. Sometimes the apex of 
the capsule falls toward the light, sometimes from it.” 
“In an early growing stage the young sporophytes seem to react some- 
what to gravity in a negative sense, tending to bend upward toward the per- 
pendicular whether lighted from above or below.” 
The following were incidental observations in connection with the experi- 
ments. The entire zone of elongation of the sporophyte (in Funaria ) is situ- 
ated inside the calyptra. The zone of elongation is limited to a space within 
2 mm. from the apex, the most rapid growth being found about 0.8 mm. from 
the tip. “ The young seta was found to have reached its complete diameter 
at any given point as soon as its growth in length was completed,” 
The calyptra appears to serve a very important purpose in preventing 
the drying up of the young sporophyte tip. In Fu 7 iaria, because of the more 
dry and exposed habitat of the species, it is only after the capsules are half 
grown that they are able to survive the drying out of a few days of hot dry 
weather. “ Hence the season for sporophyte formation falls in the moist 
season of the year when the temperature is sufficient to allow rapid growth.’’ 
In Funaria the young calyptra consists of a long beak-like distal portion, an 
enlarged sac-like portion contracted at base into a short collar-like portion 
which clasps the seta very tightly. Although this sac-like calyptra be 
removed with extreme care the sporophyte will not develop unless the cap- 
sules be half grown. Dr. True infers that this is due largely, if not entirely, to 
the drying out of the fcapsule after the removal of the calyptra. The cells of 
the calyptra have abundant chloroplasts, and Dr. True believes that it has 
powers of independent nutrition, but is somewhat in doubt as to the source of 
its water supply, which is apparently the minute quantity of Water usually 
to be seen in the upper part of the calyptra during the earlier stages of 
sporophyte development. As Mnium cuspidatu?n grows in moist situations 
its calyptra can be, and is, spared much earlier. Brooklyn, N. Y. 
DO YOU WANT YOUR POLYTRICHACEAE IDENTIFIED? 
In the course of some work on the Polytrichaceae of western North 
America, to be published later, the writer has had occasion to attempt the 
elaboration of serviceable keys to the species of the family. To test these 
keys, and to get a wider acquaintance with the variations in the group the 
writer would be pleaSbd to receive for determination, verification, or simply 
for examination, collections of Polytrichaceae, including the genera Cathari- 
nea (Atrichum), Oligotrichum, Bartramiopsis, Polytrichadelphus, Pogona- 
tum, Polytrichum. T. C. Frye, 
State University, Seattle, Washington. 
