Physiology of the Genus Cuscuta. 107 
If now the tip of a haustorial swelling be cut off and 
examined with a little of the starch and plaster still adhering, 
it will be seen that the haustorium has not penetrated the 
overlying epidermis, but that the epidermal cells have become 
papillate, and that most of the starch-grains still existing, 
either in contact with or very near the papillae, are deeply 
corroded. The corroded starch-grains can more accurately 
be observed, however, if after cutting off a bit of the stem 
in contact with the rod, some of the mixture still adhering 
to the tips of the haustorial swellings be removed to a slide, 
spread out thereon, and examined in a drop of water. 
Evidently then the starch in contact with and in the 
vicinity of the papillate epidermal cells has been acted upon 
by them. That starch-grains not in contact with these cells 
are also acted upon shows that the ferment which is secreted is 
capable of diffusion for some distance through plaster of Paris, 
however limited may be its power of diffusion through 
colloids 1 . Examination of the plaster and starch with which 
unmodified epidermal cells are in contact, that is, between the 
haustorial swellings, shows no corrosion ; the starch-grains 
are as unacted upon as those from parts of the rod far from 
the Cuscuta. The papillate cells are as well developed as 
those formed when the parasite is in contact with a host, 
showing that they have been nourished by what they have 
dissolved. The haustoria, though not so far advanced as they 
would be in the same length of time had a living plant been 
used instead of a rod, have yet developed farther than they 
would had an entirely insoluble and innutritious support like 
glass been used. The solvent action of the papillate cells 
results, therefore, in the acquisition of food used not only by 
themselves but by the haustoria also. 
Since starch is contained within the cortical tissues of the 
host, it remains to be shown whether the papillate epidermal 
cells of the parasite reach this food-supply merely by rupturing 
1 Brown, H. T., and Morris, G. H., A Contribution to the Chemistry and 
Physiology of Foliage Leaves. Journ. Chem. Society, London, May, 1893, 
pp. 656-8. 
