1922] KNUDSON—ORCHID SEEDS 19 
dioxide is soon exhausted. In the larger flasks, however, the volume 
of air, and therefore the volume of CO,, is much greater, from six to 
twenty-five times as great, and furthermore, the area through 
which the CO, can diffuse is greater by virtue of the larger mouths 
of the flasks. That the diffusion of CO, is impeded by a cotton 
stopper was shown in a previous paper (KNUDSON 7). 
From the practical standpoint this would seem to be a method 
for the propagation of orchid seeds. The seeds may be germinated 
in the small culture tubes or in larger containers, and when roots 
are produced they may be transplanted either to pots in the open 
or transferred to sterile culture in larger flasks. My efforts to 
develop the seedlings on peat sphagnum mixture in flower pots in 
the open resulted in failure on several different occasions, due in 
one case to the temperature running up to 40° C., which permitted 
a pathogenic fungus to destroy utterly the seedlings in about 
twenty-five pots. In another case, during an absence from the 
city the seedlings were destroyed by insects. Previous to the 
misfortunes which the seedlings experienced they had been growing 
for periods of three and four months and were making satisfactory 
development. Other experiments are now in progress on this 
phase of the question. Some tubes were sent to Mr. T. L. Mean, 
of Oviedo, Florida. Some of these were transplanted four. and 
five months ago, and according to a recent communication from 
Mr. Meap, the seedlings transferred are continuing growth, and 
but few seedlings were lost as a result of transplanting. The 
results of certain experiments now in progress indicate that more 
rapid growth will be obtained if the culture seedlings are trans- 
ferred to sterile media containing sugar and grown for a year or 
two under these conditions. This method, moreover, has the 
advantage that the seedlings are not exposed to the depredations 
of insects or the ravages of parasitic fungi. Furthermore, con- 
tamination of the cultures by Penicillium or Aspergillus is without 
any injurious effect, provided that at the time of transplanting 
the seedlings have roots. 
Discussion 
What is the significance of these results in relation to the views 
advanced by BERNARD and BurGEFF, and quite generally believed 
