May, 1922. ] THE ORCHID REVIEW. 135 
NONSYMBIOTIC GERMINATION OF ORCHID SEEDS. 
N our March issue reference was made to the method adopted by Messrs. 
Charlesworth & Co. in the raising of Orchids from seed. The success 
achieved by this firm is ina large measure due to the use of a compost 
which is first sterilised and then infected with the necessary fungus. When 
sufficient time-has elapsed for the fungus-to permeate.this compost, the seed 
is sown, and germination takes place with regularity and rapidity. This 
union of fungus and seed may be described as a symbiotic relationship. 
But can Orchid seeds be made to germinate by any other means; that — 
is, without the aid of fungal infection? In the Botanical Gazette, January, 
1922, Mr. Lewis Knudson, writing from the Laboratory of Plant Physiology, 
Cornell University, U.S.A., states in an article on the Nonsymbiotic Germ- 
ination of Orchid Seeds that germination of seeds of Lelia, Cattleya, and 
related forms is possible without the aid of any fungus when certain sugars 
are supplied. Experimental results with eighteen different culture solutions 
show that fructose is more favourable for growth of the embryos than glucose. 
An interesting observation was that embryos in sugar-containing cultures 
accumulate a considerable reserve of starch. 
Mr. Knudson remarks: “ The increasing importance of Orchid culture 
in America, the difficulties in and the restrictions on the importation of 
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 Burgeff, indicating that soluble organic com- 
pounds might cause germination, and my own previous experiments on the 
organic nutrition of plants, demonstrating that various sugars have a very 
favourable 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 cultures were all grown under aseptic conditions. For sterilizing 
the seeds, the calcium hypochlorite method of Wilson was adopted. This 
consists of ro gm. of calcium hypochlorite in 140 cc. of distilled water. 
After filtering, the clear liquid is placed in a small test tube with a quantity 
of seed and shaken until each seed is moistened, the process being repeated 
several times. The seeds are then transferred by the use of a platinum 
needle, about 100 at atime, and scattered over the nutrient agar in the 
culture tubes. A method is described of transplanting the seedlings from’ 
tubes to larger flasks. Efforts to develope the seedlings on peat sphagnum’ 
mixture in flower pots in the open resulted in failures from various callses: 
The results of certain experiments indicate that more rapid growth will be 
obtained if the culture seedlings are transferred to sterile media containing: 
Sugar and grown for a year or two under these conditions. 
