38 
Mycologia 
small cutting needle was used to make a slit extending through 
the cortex and reaching the cambium, and the inoculum was in- 
troduced into each incision with a sterile needle. No protection 
of any kind was given by wrappings. An equal number of control 
incisions were made at the time. The inoculations were made on 
April 13, 1911, and a dry period followed. Conditions were so 
unfavorable for growth during the following months of spring 
and summer that successful inoculations were not anticipated. 
The results are given in the following table : 
Inoculations of Mesquite with B. Tumefaciens 
Made 4-13-1911 ; record completed 9-21-1911 
Strain of 
B . tumefa - 
ciens used 
Age of 
shoots 
inoculated 
Diameter 
of shoots 
No. of 
inocu- 
lations 
Result 
No. of 
controls 
Result 
No. of 
galls 
Size of galls 
Hop 
3 yrs. 
8-10 mm. 
10 
I 
8 mm. 
10 
All healed 
Daisy .... 
3 yrs. 
8-10 mm. 
10 
0 
10 
All healed 
Daisy .... 
2 yrs. 
6 mm. 
10 
2 
13 and 10 mm. 
10 
All healed 
Daisy .... 
1 yr. 
4 mm. 
10 
I 
15 mm. 
10 
All healed 
Of tbe forty inoculations, four or ten per cent, proved suc- 
cessful, producing galls ranging in size from 8-15 mm. in 
diameter after five months and eight days, after which the record 
was discontinued. Two of the galls produced were nearly 
globular and showed a small surface of attachment (pi. 116, f. 2), 
one was somewhat flattened and elongated parallel with the axis 
of the s'hoot, and the fourth was globular-depressed. In no case 
did the control punctures show any abnormal growth, and all 
were perfectly healed when the record was completed. 
The above record is not presented as conclusive evidence that 
the galls common on the mesquite throughout the southwest are 
of bacterial origin, but it at least affords a basis for this pre- 
sumption. The inoculations reported do show at least that B. 
tumefaciens can produce aerial galls on the mesquite. 
Zoology Building, 
University of Pennsylvania. 
Philadelphia, Pa. 
