43 
Mac Dongai. — Symbiotic Saprophytism. 
retain such comparatively enormous shoots as does Ptero- 
spora , with stomata, the latter organs being also found on 
another dicotyledonous saprophyte with relatively small aerial 
members. 
Recapitulation. 
1. Saprophytism is an adaptation of the absorbent me- 
chanism, or of the character of the metabolic capacity of an 
organism. Symbiotic saprophytism is the natural result of 
the supplemental capacities of two organisms brought into 
nutritive contact chemotropically. 
2. Fungi comprised in the Oomycetes, Gasteromycetes, 
Hymenomycetes, and Pyrenomycetes, may form mycorhiza. 
They are capable of independent existence, and undergo 
modifications of the hyphae and reproductive organs in the 
portion of the mycelium in contact with the protoplasm of 
the higher symbiont. Sporangioles, vesicles, and hyphal 
clumps are organs of nutritive interchange. 
3. The changes of the member of the higher symbiont 
harbouring the Fungus are of two kinds. One by which the 
degeneration of normal structures results, a very common 
condition. A second by which special cells are formed for 
the accommodation of the Fungus. 
4. The cells entered by the hyphae generally show a 
decrease of carbohydrate, and an increase of proteid content. 
The morphological changes consist in fragmentation, distor- 
tion, increase in size and staining properties, and sometimes 
position of the nuclei, and in certain instances in repeated 
cell-division. 
5. The velamen of terrestrial and aerial roots, and the 
trichomes of coralloid structures, are devices which facilitate 
absorption by endotropic Fungi. 
6. Generally mycorhiza is not formed on specialized storage- 
organs. The fleshy-rooted Orchids are an exception however. 
7. Mycorhizal Fungi sometimes penetrate non-absorbing 
organs. This is found in P eramium (Goody era), Aplectntm , 
and probably Calypso and other Orchids. 
