1922] KNUDSON—ORCHID SEEDS 7 
with 75 cc. of water. The extracts were filtered, and to the clear 
filtrate 1.25 per cent agar was added. Seeds of Cattleya labiata x 
C. aurea were sterilized and planted on February 14, 1919. On 
May 13 some of the seeds in each had germinated and the remainder 
were almost germinated, that is, they were just at the point of 
producing the first leaf. | 
EXPERIMENT 3.—The media used were Pfeffer’s alone and 
Pfeffer’s plus 1 per cent sucrose. Seeds of Cattleya mossiae were 
planted on January 14, 1919. On July 1 the seeds in the sucrose 
culture had germinated, one leaf showing. On the Pfeffer’s alone 
the embryos were in a small green spherule stage, the diameter 
being about 250u, while the diameter of the embryos on sucrose 
was about 1000p. 
EXPERIMENT 4.—Seeds of Cattleya intermedia XC. Lawrenceana 
were sown on July 18, 1919, on solution B plus 2 per cent glucose 
on the one hand and 2 per cent sucrose on the other. Owing to 
an absence from the University, the cultures were not examined 
until June 9, 1920. At that time, in both glucose and sucrose 
cultures, the seedlings were well developed, although the culture 
-media had lost most of the water by evaporation. The seedlings 
had two or three leaves and one or two roots, some of the roots 
being 4 mm. in length. 
Influence of certain sugars and plant extracts on germination 
The preliminary experiments show that germination of seeds 
of Cattleya and Laelia is possible without the aid of the fungus, 
provided soluble organic substances are present, particularly 
sugars. In all these cases the leaf point appeared only after three 
months, and yet under practical greenhouse conditions, when the 
seeds are sown merely on a compost of peat and sphagnum or other 
organic material, the leaf points may appear in a shorter time. 
For example, according to Mr. T. L. Meap, of Oviedo, Florida, 
seeds of Cattleya have shown leaf points in as short a period as 
thirty-five days. Some of the media used by him were oak bark, 
magnolia bark, and a compost of decayed leaves and sphagnum. 
It is possible, of course, that under these practical conditions 
the fungus is a factor in the growth. Is it possible also that certain 
