482 
F. L. PICKETT 
chloride tube, L, was so connected that at the beginning of deliques- 
cence of its contents it could be replaced by a fresh tube. A current 
of carbon dioxide was made to pass through this apparatus for 2 hrs. 
and then a current of air from the pressure apparatus for 18-24 hrs. 
before the specimens were placed in the drying tubes. In use the 
rate of air passage was slightly more rapid than in I. 
IV-V. As checks on the experiments in which air currents were 
used two Fresenius closed desiccators were used, one (IV) with a 
2 cm. layer of fused calcium chloride in the bottom and the other (V) 
filled I cm. deep with c.p. sulphuric acid. Parallel check experiments 
with soil and green tissue show the desiccation in the air currents and 
in the closed desiccators to be the same. Because of the slow passage 
of air in I and II, but small quantities of material will be dried 
quickly. 
C. rhizophyllus , Extreme Desiccation. — Portions of soil of about 
.25 cc. volume, bearing well-developed prothallia with mature an- 
theridia and archegonia were removed from the culture saucers to 
the drying tube as noted above. Several such clumps of soil and 
plants were placed in a tube at one time so that portions could be 
removed each day as wanted, with a minimum danger of mutilating 
the plants. For recovery the desiccated soil and plants were placed 
lightly on moist sterile soil under a bell jar in full diffused light in the 
greenhouse. In all cases recovery or survival has been taken to mean 
the ability to continue growth or to produce living sperms. The 
averages of results of experiments with the various methods are given 
below. The time in days is reckoned from the time when plants were 
put into the drying tube up to that of removing a clump which failed 
to show a living plant. The variation did not exceed one day in any 
case of duplicate experiments. The clumps were removed for revival 
at 8 A. M. each day. No attempt was made to determine the exact 
number of hours required for fatal exposure. Individual differences 
of plants would make such work extremely difficult; and the results 
would in the end be but averages for the species, such as we have by 
the method employed. 
Results. — I. Glycerine desiccator all plants dead on the 7th day. 
II. Sulphuric acid desiccator " *' " " " 7th " 
III. Calcium chloride tube. " " '* " " 6th " 
IV. Fresenius, calcium chloride " " " " " 6th " 
V. Fresenius, sulphuric acid " " " " " 6th " 
