1922] KNUDSON—ORCHID SEEDS 3 
case in which the introduction of the fungus was followed by death 
of the seeds or failure to germinate. He states as follows: 
The germination by inoculation is not obtained without certain difficulties. 
For five years I have sown seeds of diverse species of orchids in culture tubes, 
each of which contained 100 seeds, and these I have inoculated with Rhizoctonia 
obtained from the roots. Altogether, I have obtained a few hundreds of 
seedlings, but I underestimate when I place the number of seeds used in my 
experiments at 50,000. For the majority of the seeds, the association with 
the fungus that I have placed in their presence has been merely passive and 
without effect, or impossible or rapidly injurious to the embryos. 
The explanation generally offered in these cases is that “‘ac- 
tivity” of the fungus was altered or the proper strain was not 
employed, so that the essentially delicate balance between the 
fungus and the embryo was not maintained. 
In certain experiments BERNARD succeeded in germinating 
seeds of Cattleya and Laelia without the intervention of the fungus. 
This was accomplished by using a more concentrated solution of 
salep. Salep (KiNG, 6) is the dry powder obtained by pulverizing 
tubers of certain orchids, and contains, principally, mucilage 48 per 
cent, starch 27 per cent, and proteins 5 per cent. It probably 
contains also some sugar as well as soluble mineral matter. The 
seedlings obtained in this way were in every respect normal and 
the germination was very regular. BERNARD suggests that some 
such method might be developed for practical purposes, since the 
results with the fungus are so unsatisfactory. 
The increasing importance of orchid culture in America, the 
difficulties in and the restrictions on the importation of orchid 
plants, and the desirability of creating new hybrid forms, make 
particularly desirable a method for germinating the seeds. Certain 
data from the experiments of BERNARD and BurGErFr, indicating 
that soluble organic compounds might cause germination, and my 
own previous experiments (7) on the organic nutrition of plants, 
demonstrating that various sugars have a very favorable influence 
on growth, are indications that germination of orchid seeds might 
be obtained by the use of certain sugars. This proved to be true. 
The results here reported describe a method for germinating 
the seeds under sterile conditions, the influence of certain sugars 
