3i 2 Dey. — Studies in the Physiology of Parasitism. V. 
Figs. 4, 4 A. Germinating spore, showing mucilaginous sheath round the appressorium : drawn 
from fresh material stained with dilute gentian violet, x 1050. 
Fig. 5. Germinating spore attached to the epidermis. The germ-tube is curved and is fixed at 
both ends, x 1500. 
Fig. 5 A. A slight protuberance on the appressorium causing an indentation of the wall of the 
host. The mucilage round the appressorium appears to be reduced to thread-like structures, x 1500. 
Fig. 6. The ‘ infection hypha’ has grown out from the appressorium and penetrated the cuticle, 
x 1500. 
Figs. 7, 8. The ‘ infection hypha ’ is growing in the subcuticular layers after effecting its entrance 
by perforating the cuticle. The hole produced in the cuticle is somewhat wider than the ‘ infection 
hypha’. x 1500. 
Fig. 9. A somewhat later stage than Fig. 8. Swelling and disorganization of the cell-wall is 
clearly seen, x 1500. 
Figs. 10, 11. The ‘infection hypha’ is swollen into a vesicle in the disorganized cellulose 
layers, x 1500. 
Fig. 12. A somewhat later stage than Fig. 11. The vesicle has given origin to a branch, 
x 1500. 
Fig. 13. The vesicle and its outgrowth are visible. Swelling and disorganization of the sub- 
cuticular layers have taken place. The protoplasm of the epidermal cell appears to have accumulated 
in the upper part of the cell, probably as the result of the action of the invading hypha. x 1500. 
Fig. 14. The ‘infection hypha ’ has formed the vesicle after passing into the cavity of the cell. 
Disorganization of the wall and the protoplasm has occurred, x 1500. 
Fig. 15. The ‘ infection hypha ’ has passed into the cavity of the epidermal cell. Disorganization 
of the protoplasmic contents is well advanced. The break in the cuticle is now much enlarged and 
the appressorium is pressed slightly into it. The ‘ infection hypha ’, which is very narrow at its base, 
has swollen into a hypha of normal size in the layers of the cell-wall below the cuticle. The 
protoplasm of the cell appears to have accumulated round the ‘infection hypha’. x 1500. 
Fig. 16. The ‘infection hypha’ passing into the cavity of a guard cell has swollen out into 
a vesicle, and has caused shrinkage and death of the cell, x 1500. 
Fig. 17. The appressorium has formed over a stoma. The ‘injection hypha’ is growing down 
through the pore of the stoma, x 1500. 
