EXPERIMENT SIATION REPORTS 69 



species of leaf-roller. Thus far its work does not seem to have been very 

 general or harmful, but there are disagreeable possibilities in any such 

 case, and our studies of this insect are being prosecuted with a view to 

 meeting any developments which may occur. 



The preceding paragraphs give an incomplete outline of the work of 

 the department during the past year. A bulletin on the insects of the 

 year 1898 is now ready for the printer, and in it will be found further 

 details of the work on"^ some of the species mentionod above, as well as 

 other matters which it is believed will be of value to the agriculturists 

 of the State. 



Respectfullv, 



WALTJER B. BARROWS, 



Consulting Zoologist. 

 Agricultural College, Mich., 

 June 30, 1899. 



REPORT OF THE BACTERIOLOGIST. 



Director CD. ^mith: 



Dear Sir — The bacteriological investigations for the past year may be 

 included under three heads. — hygienic, dairy and plant bacteriology. In 

 hygienic work we have had to deal with tuberculosis and the so-called 

 hog cholera; in dairy manipulations our attention has been called to 

 cleanliness in handling milk, and gassy cheese; and in plant diseases our 

 efforts were directed at the causal agent of crown gall in peach trees. 



The general plan adopted on the start for the investigation of tubercu- 

 losis has been followed as closely as circumstances would allow. The 

 hygienic treatment and isolation of the tuberculous animals, together 

 with the breeding of the condemned animals, have been brought to a con- 

 clusion in large part by the slaughter of the animals and the returning 

 of two or three to the sound herd. Although it would have been intensely 

 interesting to follow these animals until they had either recovered from 

 the disease or had succumbed to it. yet it was thought that they had 

 served all practical purposes, inasmuch as some of them had become in- 

 capable of producing off-spring. 



The tuberculin test was carried out with all due precautions, such as 

 were employed the year preceding. There were evidences of possible 

 error in the tuberculin test disclosed, and, again, we repeat the warning, 

 there should be as many normal temperatures taken previous to injec- 

 tion as time and expense will permit. Furthermore, it has been demon- 

 strated that an animal may, after reacting once, pass over two years 

 without reacting, notwithstanding the fact that it has been tested semi- 

 annually. No new cases of tuberculosis were found this year, unless it 

 be one about which there is some doubt. What the tuberculin test has 

 done with the college herd in weeding out tuberculosis cannot be over- 

 estimated, and its value as a diagnostic agent, although not infallible, 

 canno.t be questioned in the light of our present knowledge. It can be 

 thoroughly recommended for common use. Every herd in Michigan should 

 be tested, because it is a matter of economy. If tuberculosis is checked at 

 the present moment, it means that the disease will not spread. That it 



