xg BOTANICAL GAZETTE ; [JANUARY 
leaf at the age of eight months. Burcerr does not state that the 
uninoculated cultures were maintained under the same condition, 
but presumably they were. Granting that the uninoculated cul- 
ture did not produce leaves, it is possible to explain the germina- 
tion on the basis of the inversion of sucrose, which would yield 
approximately concentrations of both glucose and fructose molecu- 
larly equivalent to the original sucrose concentration. In addition 
there is to be considered the possible influence of products secreted 
by the fungus or produced on decomposition of the fungus. 
The favorable influence of saprophytic fungi and _ bacteria 
demonstrated by my experiments is paralleled by certain cultures 
of Burcerr. He transplanted four months’ old seedlings to a 
mineral nutrient medium containing salep. Some of the cultures 
became contaminated with saprophytic organisms. The uncon- 
taminated culture showed little growth, if any, after three months; 
while the culture contaminated by Penicillium made a marked 
growth, the leaves being 4cm. in length. Another saprophytic 
fungus in another culture likewise caused a marked increase in 
growth, the leaves being about 9 mm. in length; and in a third 
culture contaminated by bacteria the seedlings were of similar char- 
* acter to those of the pure culture, but apparently darker green in 
color. All of these seedlings had produced vigorous roots. In the 
pure culture some of the seedlings had died. BurceErr considers 
that the more favorable growth in the tube with fungus contamina- 
tion was due to the development of an acid reaction in the medium. 
There is a possibility that increased carbon dioxide content and 
other products produced by the organism are partly responsible. 
It should be stated that the seedlings originally transferred to these 
tubes had previously been infected by the essential fungus. 
Another experiment of Burcerr lends weight, however, to the a 
idea that the fungus is effective in inducing germination as a result 
of certain reactions brought about within the embryo. In this 
experiment the culture medium consisted of a weak nutrient solu- 
tion plus 5'; per cent starch. Seeds of a Laelia-Cattleya cross were 
planted, and the root fungus from each of seventeen different 
orchids was tested for its ability to induce germination. In the a 
cultures uninoculated the embryos attained a width of 0.45 mm. — 
in four months. In certain cultures only the suspensor became — 
FRE SS Sa ER eee 
