412 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
lead, and the “progressive”? who breaks from the ranks must do so 
at his peril, let us keep alive to the need of progressiveness, and be 
patient with the man who challenges a traditional idea. Of course, 
every American recognizes fire blight of pear as the “classic”? among 
bacterial diseases. But there may be blight which is not the bacterial 
fire blight. It is a wholesome thing, therefore, to have a challenge 
issued. It has been too easy, at least in horticultural circles of the 
west, to attribute all types of blighting of pear and apple trees to 
Bacillus amylovorus. One of the most reassuring things about the 
chestnut blight situation has been the fact that from the outset there 
have been those who must be converted. I have for years been 
convinced that American pathologists have relied too implicitly on 
authority in attributing all potato scab to one organism. Now that 
our so-called “‘Oospora scabies”? seems to be of a bacterial nature! 
and the powdery scab of Europe is threatening if not invading our 
territory, we may hope for a revival of first-hand investigations. 
And may we not be in danger of generalizing too broadly with refer- 
ence to galls? The brilliancy and thoroughness of the recent work? 
upon crown gall will almost inevitably encourage this in spite of the 
guarded and conservative statements made by the authors themselves. 
The natural consequence of the general acceptance of the fact of 
bacterial diseases of plants, coupled with the lack of adequate training 
in bacteriological technique, led many in the early days to attribute 
numerous diseases to bacteria upon incomplete evidence. Nor was 
this confined to America. European literature, especially the French, 
has many such announcements. We need not criticise these too 
severely as to the past. It was natural and inevitable. But we are 
increasingly blameworthy if we continue either to publish carelessly 
or to accept the announcements of others without critical review. 
With the appearance of Smith’s monographic work on Bacteria in 
Relation to Plant Diseases, any American, at least, who describes a 
“new” bacterial disease of plants upon inadequate data should realize 
that he is committing an offense against the American profession. 
This is not to imply that there are not plenty of bacterial diseases 
of plants yet to be discovered, nor to discourage the search for these. 
It is rather to emphasize that there are other problems better worth 
while than the search for ‘‘new”’ diseases of minor economic impor- 
tance. The simplicity of the bacteria in their relations to host and 
in the way they lend themselves to culture and infection stimulate 
the hope that through persistent intensive study of bacterial diseases 
we shall gain the clearer insight into those intimate relations of para- 
site and host which are fundamental to the science of plant pathology. 
is sia E. F. Crown gall of plants. Phytopathology 1:7. 1911. Smith, Brown, and McCulloch. 
The structure and development of crown gall: A plant cancer. U.S. Dept. Agric., Bur. Pl. Ind., Bull. 
255, 1912. 
