1gto] BRIEFER ARTICLES 221 
with mycology, bacteriology, plant pathology, and plant physiology. The 
connection with entomology is fully appreciated and needs no comment 
at this time. Many fungi produce cecidia, but the character of these 
cecidia have received as little or less attention from the mycologist than the 
insect cecidia from the entomologist. The cecidia on the roots of legumes and 
the recent investigations of Smita and TowNSEND on crown galls demon- 
strate the relationship to bacteriology. Since the cecidia from whatever 
Cause are pathological conditions of the plants, cecidology becomes a well- 
defined part of plant pathology. Until recently, plant pathology has been 
more especially interested with the cause and control of diseases, in fact 
has been a branch of mycology. However, with the further progress of 
the subject we must come more and more to recognize the necessity of a 
study of the pathological condition of the plant. This feature of the work 
will involve the most careful and exact methods of the plant physiologist. 
However, the connection of cecidology with physiology is not only through 
pathology, but direct. There is that long-mooted question concerning 
the character of the stimuli in the formation of cecidia, which has never 
been answered satisfactorily. | 
An explanation of the character of the stimuli in the formation of 
myco-cecidia might give some aid in answering the question, and this 
latter problem is undoubtedly within the province of plant physiology. The 
explanation of why injuries result in hypertrophies in some cases and atro- 
phies in others is also an interesting problem for some ambitious student 
of botany. The fact that “the morphological character of the gall depends 
upon the genus of the insect producing it rather than upon the plant on 
which it is. produced,” as demonstrated by the writer,4 suggests an interest- 
ing field of investigation. The so-called evolution of the cecidia may be a 
Fesponse to physiological conditions rather than to evolutionary factors. 
The distribution of cecidia as compared with the distribution of the 
host plant furnishes a good supply of work for the ecologist, while the inju- 
tious character and valuable properties of many cecidia will give profitable 
fields for the economic phases of the biological sciences. 
The greatest need of cecidology in America at the present time. is the 
Cataloguing and indexing of the literature and the indexing of the cecidia 
with reference both to the causes and to the host plants. To this should 
be added up-to-date, available descriptions of the cecidia and the organisms 
Which cause them. Some work along this line has been done by Mr. Wo. 
BEUTENMULLER of the American Museum of Natural History, and by 
the writer. 
*Coox, Met. T., Galls and insects producing them, Ohio Naturalist 2:263-. 
278. tgor. 
