MacDougaL — Symbiotic Saprophytism . 1 9 
from the endotropic Fungus as well as reserve material, while 
the ectotropic Fungus is developed only sparingly. 
A dozen specimens of Aplectrum received from Mr. F. H. 
Horsford, March 35, 1898, showed three in which coralloid 
structures were beginning to form on the offshoot. The 
coralloid formations have thus been found on specimens 
growing at three different points in a line fifteen hundred 
miles in length, extending through a region in which the 
character of the soil and climate is fairly identical. Lund- 
strom has described similar formations on Calypso borealis (' 23 ). 
Experimental formation of coralloid structures or stem - 
mycorhiza . A theoretical consideration of the problem of the 
formation of the coralloid stems leads to the conclusion that 
these structures might result from the parasitism of the 
investing Fungus, from an effort on the part of the plant to 
increase its absorbing surface, or from the awakening of all 
of the lateral buds as a reaction to the destruction of the 
apical growing-points. The anatomical inspection described 
above failed to show any parasitism on the part of the 
mycorhizal Fungus, or the presence of a second organism 
having this effect. In order to determine to which of the 
remaining causes these formations were due, a series of tests 
were made as follows. In one series the apical buds of 
a number of young offsets were cut away and the plants 
placed under the most favourable cultural conditions. In 
another the roots were cut away from the bases of newly- 
formed corms at the extremities of offsets, leaving only the 
cylindrical offsets as absorbing organs. In another the old 
corms were taken away leaving the half-grown daughter- 
plant without its customary supply of reserve nutriment. 
In a fourth series, old corms which were nearly spent but 
which still showed living dormant buds, were separated from 
the daughter-plants. The first three sets of experiments 
gave only negative results. In no instance could the develop- 
ment of the lateral buds be induced by the decapitation of 
the offset. The excision of the roots or of the reserve food 
in the old corms tended only to induce the formation of new 
