1893.] Bacteriology in its General Relations. 853 
atmosphere. In reviewing the progress of agricultural bacteri- 
ology, we can only allude to the lines of work which have been 
opened up in this fertile field of research. It may be confi- 
dently asserted that as yet, we stand on the threshold of dis- 
covery in this department, and the work can scarcely be said 
to be more than inaugurated. What the possibilities of the 
future are, no man can safely predict. 
Study in veterinary pathology has gone hand in hand with 
that of human disease, and the etiology of numerous con- 
tagious diseases in domestic animals have been thoroughly 
investigated. Actinomycosis in cattle, glanders in horses, 
and splenic fever in sheep besides numerous other septicemic 
diseases, like hog-cholera, swine plague, chicken cholera, 
rouget or swine erysipelas are classic examples in our text- 
books. A fuller knowledge of the history and etiology of 
this class of diseases, has not only better enabled the farmer 
to check their spread, both by remedial and prophylactic 
treatment, but it has awakened an economic interest that is 
steadily progressing along practical lines. 
Besides these parasites, confined to animal organisms, the 
husbandman has to contend with a series of forms, which 
only find their normal hosts in vegetable tissue. The farmer 
and horticulturist need to be always on the alert to protect 
their harvests from the ravages of these enemies. Insects and 
fungiare an ever present menace to success, but not a small 
number of plant maladies are to be traced directly to a 
bacterial source. Such destructive diseases as the apple and 
pear blight, the tuberculosis of the olive, the “ yellows " of the 
hyacinth, as well the blight of oats, sorghum, Indian corn, 
and other cereals are often due to an invasion of germs of a 
bacterial nature. The conditions by which these diseases are 
propagated and spread are such, that some of them can be 
eradicated, now that we know how the infection is transmitted. 
To illustrate, the pear or fire blight, which has been observed 
in this country for a hundred years, and which in some sec- 
‘tions has become so destructive as to practically ruin the 
industry, can now be managed with comparative ease. 
Through the researches of Waite, it has been ascertained that 
