Von SCHRENK: TEACHING OF VEGETABLE PaTHOLOGY 59 
as sharply defined as in animals. This is due in part to the lower 
degree of organization of the plant, and also to the fact that a good 
many disturbing factors give rise to similar symptoms. We can, 
however, analyze the symptoms with far greater ease than is pos- 
sible in animals. Environmental conditions can be controlled, and 
by a method of elimination the distu rbing factor can be determined 
positively. The study of the disturbing factor, whether it be en- 
vironmental or due to living organisms, can also be carried on 
with more success with plants than with animals. In other words, 
we can make the study of pathology one involving experimenta- 
tion with living plants. 
This brings me to speak of the things necessary for a course in 
pathology conforming to the above. In the first place one or 
more greenhouses are absolutely essential, together with a liberal 
Supply of living plants. If carried on in the spring and summer 
the greenhouse is not so essential. Access to greenhouses where 
different kind of plants are growing is also desirable. In St. 
Louis we have established a vegetable clinic, where patients are 
received and observed. The greenhouse, or houses, ought to be 
divided into numerous compartments, each completely sealed from 
the others preferably, so as to prevent the spreading of fungus 
Spores. I wish to call attention to a series of houses built by Dr. 
von Tubeuf at Dahrlem, near Berlin, which are ideally arranged 
for work in experimental pathology. The number and kind of 
Plants needed depend largely upon the amount of work which one 
contemplates doing. Wheat, corn, oats, cabbages, roses, lettuce, 
Cotton, and other common plants easily obtained, will be found 
ample in most cases. Living material of fungi, obtained from 
diseased plants, or kept as cultures, will also be essential. 
Before proceeding further a word ought to be said about the 
Preparation which we ought to expect of students engaging in this 
ae As pathology is essentially abnormal physiology, a thor- 
Ough knowledge of plant physiology should be required. This is 
S© obvious that it is hardly necessary to urge it, and yet it isa 
| “unous fact that, so far as I have been able to determine, this is 
anded, and that not very decidedly, in only one institution. 
°° much Stress cannot be laid on this requirement, and under no 
: Pie deration Ought pathology, as we now understand it, to be 
