PHYTOLOGY AND THERAPEUTICS. Me 99 
than the others. These results, taken in connection with those obtained from 
pure Massachusetts soil, seem to indicate that the micro-organisms are suffi- 
ciently numerous and active for ordinary inoculating in a comparatively small 
amount of the Massachusetts soil,and that an increase of this infectious soil 
does not perceptibly increase the number or size of the tubercles. 
Errecr of LicgHT oN THE Micro-orGANIsMs.—Two broad, shallow dishes, 
each with about 210° of the Massachusetts soil spread over their surfaces, were 
placed, one in diffused light and the other 
in sunlight, and enough to inoculate one 
pot was taken from each of these at the end 
of one, two, three, four, and six weeks, re- 
spectively. In the meantime the soil was 
kept stirred so as to expose all portions 
equally to the light. All pots contained tu- 
bercles; and, although the results slightly 
favor the pots whose inoculating material 
was exposed the least, the differences are 
very small. In fact, it seems that light 
could have but little effect on the micro- 
organisms when the soil is kept together in 
any quantity. 
InocunaTine aT DIFFERENT TEMPERA- 
TURES.—To see what degrees of tempera- 
ture these micro-organisms could stand, 
soil was heated to ten different points, 
varying from 40° to 150° C. (104° to 302° F.) 
Tubercles were found in all the pots ex- 
Fig. 3 cept 120° and 150° C. Unless the micro- 
Say bear TASES naa Ae hotiaw organisms happened to possess less vitality 
of pot. in the former instance, the lack of tuber- 
cles could scarcely be attributed to the 
heat, as tubercles were found on the plants whose inoculating material was 
heated to 140° C. It was observed that the tubercles developed the best at the 
lower temperature and they seemed to decrease as the temperature increased, 
although this variation was not entirely regular. It would seem that some 
of the bacteria possessed more vitality than others and that the ones with less 
vitality were killed by the heat. A similar test was made by heating extract 
from 35° to 90° C. (95° to 174° F.); but as this was considerably lower than 
that to which the soil was heated, tubercles were formed in all the pots, as 
might be expected after the former discovery. But even here thesame gradation 
existed as was noticeable in the case of the soil, the tubercles being more numer- 
ous at the lower temperatures. In both of these cases the results show that the 
micro-organisms can stand quite a high degree of heat. 
INOCULATING WITH Kansas Sort.—Will soil which has once been inoculated 
serve to inoculate non-infected soils? First, five pots were filled with soil taken 
from the immediate vicinity of roots previously inoculated. Second, five pots 
were filled with soil which had been soaked and washed out from plants that had. 
produced tubercles in the field. Since nearly a two-foot cube was taken up with 
each hill, the number of micro-organisms must have been less in this instance 
than in the first five pots. Tubercles were produced in all the pots; but the 
results, as might be expected, were somewhat more in favor of the first five. To 
test this matter still further, two pots were inoculated each with 2lcc of the 
