nematode injuries by the plants wliich it affects. Any galls on the 

 roots of cruciferous plants growing out of doors in summer may 

 usually be considered as club root. 



The other gall-producing organism affects clover, pea, bean, 

 lupine, horse bean, cow pea, vetch, and all other legumes or plants of 

 the order Leguminosae. It is a bacterial or microbe-like organism 

 consisting of extremely minute single cells, each cell being a complete 

 individual in itself. These little organisms enter the roots of legu- 

 minous plants from the soil and reproduce and multiply there, causing 

 the root by their presence to swell up into little galls or tubercles as 

 they are commonly called. These tubercles are quite similar in 

 appearance to nematode galls. Instead of injuring the plant, how- 

 ever, they have, on the contrary, a very beneficial and remarkable 

 effect. It has long been known that leguminous plants have the 

 power which is not possessed by other plants of obtaining free nitro- 

 gen from the air. This is of course very beneficial to them. What 

 gives them this power was for a long time unknown, but it is now well 

 established that this peculiar advantage is in some way connected 

 with and due to the bacteria in the roots, though just how it comes 

 about is not yet satisfactorily determined. We do not recall any 

 leguminous plants cultivated to any extent in greenhouses, except 

 perhaps one or two flowering plants, so that no great confusion with 

 nematode injuries need arise from this source. 



Root galls may sometimes be traced to insects or other causes, 

 but not to any extent in greenhouse plants and therefore are not 

 liable to be confused with nematode galls. Galls are sometimes 

 formed on the root of the raspberrry by an insect (Rhodites radicum) 

 which are quite similar. We know of no perennial outdoor plant in 

 our climate which is affected by nematodes. 



Nature of the Galls Produced By Heterodera radicola, And the Harm- 

 ful Results Occurring From Them. 



By breaking open a gall from the roots of any affected plant and 

 carefully examining the fragments there may be seen with the naked 

 eye or more easily with a hand lens, little, white, glistening, pearl- 

 like bodies about the size of a pin head, imbedded here and there in 

 the tissue. These are the mature female worms and the cause of 

 the formation of the galls and consequent injury to the plant. Their 

 number varies with the size of the gall, or, more logically, the size 



