THOMAS: INFECTION OF APIUM GRAVEOLENS 17 
TABLE VII 
REDUCTION IN NUMBER OF SPOTS PRODUCED BY SEPTORIA ON PLANTS INFESTED BY 
NEMATODES 
Infested by nematodes A Sinai 
Vari | el el ¢ i be 
ane Se\2ei8slee|eeles|SE| 82/52] ee |2a 
SS/83)/83\|85\e5 Awe. 38) 39 I osi8s 
BO }EO SO} FR | Fa, = es|3s On a % =F 
| | ies] q | 
INGOL Ie VES | ON oo 5} 4] s | S| 51.5 5| 7 4 4 
Spots per plant... ........ be ai 5 56 19 12 T9°| °5 29 sua | abs 
of these cases were noted in connection with the fertilizer exper- 
iments previously described, in which no reduction in vigor of 
the plant or in the amount of infection could be detected. An 
attempt to produce the infestation by inoculation into the soil 
was made with ten young plants in good growing condition but at 
the end of ten weeks, no galls were evident. The history of a 
single plant which has been followed more closely will throw light 
on the réle which the nematode plays here. A plant was noted as 
“highly resistant”’ in the course of an experiment and when reinoc- 
ulated it had lost its susceptibility completely. The roots were 
very heavily infested by nematodes. The plant was placed in a 
larger pot with fresh soil and five weeks later, when considerable 
growth had been made, it was again inoculated with a control. 
At the end of twenty-eight days no spot recognizable as due to 
Septoria could be found on the plant. The control plant bore 219 
spots. Seven weeks after this inoculation the ‘“‘nematode”’ plant 
was treated with 300 c.c. of the nutrient solution described above 
with the fertilizer experiments. At this time a few small spots 
could be seen with an occasional pycnidium. The plant was 
finally inoculated six days after the addition of the fertilizer and 
thirty days later a count of 478 spots was obtained. These spots 
were for the most part small and the fructification of the fungus 
was feeble. According to the accounts of the behavior of nema- 
todes in the roots of plants, it seéms clear that the foliage is starved 
both by the disruption of t*e vascular elements and by the with- 
drawal of food materials to p: uuce the galls. Here is undoubtedly 
a clear case of the reduction of infection by a fungus parasite 
running parallel with the reduction in vigor of the host. 
