24 BULLETIN 828, U. S. DEPARTMENT OF AGRICULTURE. 
tate reaching all parts of the insect body, and the solution was also constantly shaken 
during the exposure. 
Approximately 35 striped beetles were dissected (June 29) after a 7-day feeding on 
wilted cucumber plants in pots, and inoculations were made to the leaves of as many 
cucumber seedlings by mixing the intestinal contents of each beetle in a drop of tap 
water and pricking the mixture into the leaves. These plants were kept in beetle- 
free cage with 20 or more uninoculated control plants. Two of the inoculated plants 
developed typical cases of wilt starting from the points of inoculation with intestinal 
contents. 
Finally, on July 5, 1918, the last experiment was repeated, using sixty striped and 
thirty 12-spotted cucumber beetles and fifteen squash lady birds. All had been 
previously fed for 10 days on wilted cucumber plants in pots and had been treated for 
five minutes before dissection with mercuric chlorid and alcohol, as in the preceding 
test. Five plants out of the 60 inoculated with intestines of striped beetles promptly 
developed wilt. All these cases showed the typical stringy slime from the cut ends 
of the vascular bundles, and cultures made from one of these plants gave Bacillus 
tracheiphilus. Inoculations in this experiment with intestines of the other two insect 
species gave negative results. 
These dissection experiments prove definitely that both striped 
and 12-spotted cucumber beetles may harbor the wilt organism in 
their intestinal tracts. In fact, a much larger percentage of infec- 
tions took place from intestinal contents than from mouth parts, 
although this may have been due to the fact that the mouth parts 
were harder to break up and mix thoroughly with the water on the 
leaves. They also show that only a small proportion of the beetles 
gave infection from the intestines even after feeding seven days or 
more on wilted plants. Thus, in the two tests with 12-spotted 
beetles, the intestines gave infection in about 50 and 8 per cent of the 
individuals, respectively. In the four tests with striped beetles the 
proportion varied in round numbers between 6 and 12 per cent. 
There was very little difference in the proportion of wilt carriers 
among individuals taken while feeding directly on wilted plants and 
those not feeding at all when taken for the test. 
BACTERIAL ISOLATIONS FROM BEETLES. 
One attempt was made (Dec. 10, 1917) at direct isolation of Bacillus 
tracTieipliilus from the intestinal tracts of wilt-fed striped cucumber 
beetles. 
Ten individuals were fed for two weeks upon cucumber plants wilted from pure- 
culture inoculation. They were then dipped for several seconds into 95 per cent 
alcohol, for 60 seconds in 1 to 1,000 mercuric chlorid, quickly washed in sterile water, 
and then given five more washings of several minutes each in sterile water. The in- 
testinal tracts were then carefully dissected out as described under "Dissection experi- 
ments," without allowing the body contents to come in contact with the surface of 
the beetle. The intestines in each case were crushed in sterile distilled water with a 
sterile glass rod and allowed to stand for 20 minutes, when four series of dilutions in beef 
bouillon were made. From these tubes one series of poured plates was made at once 
and another the next morning after the bouillon had become slightly cloudy. From 
most of the plates developing colonies, pure cultures of one type of bacteria (A) 
