Boyle. — Sticdies in the Physiology of Parasitism. VI. 347 
EXPLANATION OF FIGURES IN PLATE XIV. 
Illustrating Mr. Boyle’s paper on Infection by Sclerotinia Libertiana. 
All figures were drawn with the camera lucida. Figs. 1-5 (except Fig. 4) were drawn from 
fresh material. Fig. 4 was drawn from material fixed and stained in picro-nigrosin. 
Figs. 6-7. Host tissue was Phaseolus coccineus infected in turnip juice. 
Figs 12, 14, 20. Host tissue Vida Faba infected by laying leaf on pure culture of the fungus. 
In remaining figures host tissue was Vicia Faba infected from potato-mush agar drop on leaf 
surface. 
Fig. 1. Young hyphae showing mucilaginous sheath: drawn from fresh material mounted in 
Indian ink. x 616. 
Fig. 2. Older hyphae showing thick mucilaginous sheath, x 290. 
Fig. 3. Commencement of appressorium formation, x 616. 
Fig. 4. Older appressorium fixed and stained in picro-nigrosin : the points of origin of 1 infection 
hyphae’ in appressorial branches are very distinct, x 616. 
Figs. 4 a- 4 c. Stages in the production of an 1 infection hypha’ from a branch of an appressorium. 
x 773- 
Fig. 5. Young appressorium showing mucilaginous sheath : drawn from fresh material mounted 
in Indian ink. x 832. 
Fig. 6. Y'oung hyphae fixed to surface of leaf by means of mucilaginous sheath : mucilage in 
one case represented by fine threads, x 773. 
Fig. 7. Hypha growing along surface of leaf, x 773. 
Fig. 8. Cuticle depressed at points of contact of fungal hyphae. Epidermal cell collapsed 
owing to presence of fungus in tissues : chloroplasts of palisade cells underneath disorganized : 
nucleus seen at top of palisade cell, x 773. 
Fig. 9. Cuticle further indented. No chemical action apparent, x 1,091. 
Fig. 10. Appressorium in contact with cuticle : depression very marked, x 773. 
Fig. 11. Large appressorium adhering to cuticle: cuticle shows no signs of being chemically 
affected : fungus has penetrated elsewhere : lumen of epidermal cell has disappeared and walls are 
much swollen, x 1,091. 
Fig. 1 2. Penetration has taken place from one of the appressorial branches : the other is sending 
out an ‘ infection hypha ’. The modified wall is thinned out at the apex : a clear area can be seen 
in the wall, x 1,520. 
Fig. 1 3. The ‘ infection hypha ’ has penetrated the cuticle and is forming a vesicle in the epidermal 
cell: vesicle surrounded by a clear halo, x 1,091. 
Fig. 14. Penetration from an appressorium, with the formation of vesicles in the epidermal 
cells : modified wall of appressorium very distinct, x 773. 
Fig. 15. The ‘ infection hypha’ has penetrated the cuticle and is forming a vesicle: contents of 
epidermal cells being dissolved : vesicle surrounded by a clear halo : chloroplasts losing their 
definite outline : nuclei of palisade cells near the top. x 773. 
Fig. 16. Penetration from part of an appressorium: vesicle has increased in size: ruptured 
cuticle being turned inwards by growth of fungus, x 1,091. 
Figs. 17, 18. Penetration from an appressorial branch. Fungus is growing along the epidermal 
layer : ruptured ends of cuticle turned inwards by invading hyphae. x 1,520. 
Fig. 19. Hypha growing along epidermis from vesicle : ruptured ends of cuticle pushed inwards, 
x 1,091. 
Fig. 20. An ‘ infection hypha’ has entered through a stoma, x 773. 
