i o MacDougaL — Symbiotic Saprophytism. 
be taken to correspond to the 4 sporangioles * described by 
Janse, which he characterizes as occurring in non-orchidaceous 
species, and which are homologous with the ‘vesicles’ of 
the Fungi inhabiting the Orchids according to his con- 
clusions ( 16 ). 
The Corms. The compressed globose corms attain a volume 
of 2 to 5 cc., and have a glistening or pearly white appear- 
ance. The upper internode comprises about one-half of the 
bulk of the corm, and hence the nodal line marked by a 
black rudimentary scale occupies an equatorial position. The 
epidermal cells are outwardly convex, rich in protoplasm, 
with walls equally thickened. The hypoderm shows no 
special differentiation. The endodermis consists of irregular 
flattened cells separated from the hypoderm by large inter- 
cellular spaces, which give rise to the pearly white appearance 
of the corms. The walls of the three layers mentioned are 
copiously perforated, and contain numbers of starch-grains 
staining brownish red with iodine. The external layers of 
the conjunctive tissue contains numbers of raphide-cells, and 
the more slender cells near the scattered fibro-vascular bundles 
contain starch-grains giving similar reactions to those in the 
epidermal tissues. Small numbers of granules are scattered 
throughout the storage-tissue. The chief reserve substance, 
however,, is a viscid mucilaginous carbo-hydrate soluble in 
water, and coagulated by $ 5 % alcohol into granular masses, 
which readily dissolve in water. Corms one year old are 
partially emptied of their reserve substances. The most 
noticeable fact in this connexion is the diminution of the 
bundles of raphides to about one-half their original size, 
showing that the crystals are not entirely excreta or waste- 
products. The Fungus of the root was not observed in any 
instance to penetrate into the corm. 
The corm undergoes great variations in response to external 
conditions. Thus, if a portion of an offshoot giving rise to 
a corm is uncovered and exposed to the light, the resulting 
corm will consist of six or eight internodes, and will contain 
chlorophyll in the outer layers. A corm of this character, 
