562 Waterhouse . — Studies in the Physiology of Parasitism. VII. 
When the germinated sporidia are fixed and stained the remnants of 
the mucilaginous covering appear as irregular threads and granules (Figs. 7, 
11, 16). Frequently masses of sporidia adhering together were observed, 
both in the germinations on the slide and on the barberry leaf. It was not 
possible to trace any transition from a narrow well-defined wall to a wide 
indefinite gelatinous investment as described for Botrytis cinerea ( 1 , Fig. 3). 
Penetration of the host . Sporidia were observed to have penetrated 
into the epidermal cells of the barberry leaf in 20 hours. In fixed material, 
sporidia were seen closely adherent to the leaf surface 17 hours after the 
teleutosori had been placed on the leaf. No mucilaginous sheath was 
demonstrated in the case of ungerminated sporidia, but it is possible that 
a certain amount of gelatinization of the spore wall may take place, 
anchoring the sporidium to the cuticle. Irregular threads and granules are 
commonly seen in the immediate neighbourhood of the sporidia and may 
represent the remains of this mucilage. 
On the leaf, germination may result in the production of a definite 
germ tube. This may develop quickly into a vesicle (Fig. 7), or may grow 
on for some distance before it reaches the cuticle (Fig. 8) and becomes 
closely adpressed to the surface. In other cases the germ tube is seen to 
ramify and grow over the surface for a considerable distance without 
forming an appressorium. 
Instead of producing a definite germ tube, it frequently happens that 
from the end of the sporidium a short beak-like infection hypha is put out 
(Fig. 9) which presses closely on the cuticle and may produce a slight 
indentation in it (Fig. 10). In some cases the growth of the beak-like infection 
hypha forces the end of the sporidium away from the leaf surface (Fig. 11) ; 
the tip of this hypha is densely protoplasmic. The hypha then produces 
an extremely fine style-like structure which penetrates the wall of the 
epidermal cell (Figs. 13 and 14). In appearance and in its size relative to 
the body of the sporidium, it reminds one of the proboscis of an insect. 
This style is pushed through the cuticle and underlying cellulose layers of 
the epidermal wall (Figs. 13, 14, and 15). A very careful study of the 
cuticle at the point of entry was made, but no swelling or any sign of 
alteration in its staining properties could be detected. This penetration 
of the wall by the stylar outgrowth is rendered possible by the firm adhesion 
to the cuticular surface which results from the mucilaginous investment of 
the germ tube. It therefore seems clear that the penetration of the cuticle 
is brought about mechanically by the pressure exerted by the style-like 
apex of the infection hypha. No alteration in the nuclei, when these were 
present in the epidermal cells, or in the cellulose layers underlying the 
cuticle, could in any case be detected at this stage. 
In the barberry leaf, no stomata are present in the upper surface of the 
leaf, so that entrance into the host always takes place by puncture of the 
