enlargements of the roots, more or less roundish, but very- 

 irregular in shape and varying in size. These galls are some- 

 times very prominent both in size and number, but at other times are 

 small, few, and inconspicuous. Their number depends entirely upon 

 the abundance of the worms. The size and shape of the galls 

 depends also to some extent upon the abundance of the worms and 

 their location in the root, but in different kinds of plants we find galls 

 which are somewhat characteristic in appearance. This is very 

 natural when we consider that the gall is a growth of the plant itself 

 and has no organic connection with the worm. As different plants 

 produce different shaped leaves, flowers, fruits, etc., under the com- 

 mon influence of nature, so they may produce galls of different 

 shapes though the worm which causes them is the same. 



The smallest galls with which we have met occur on the violet, 

 none being larger than a small pea and most of them being incon- 

 spicuous swellings near the tips of the rootlets. They might easily 

 be overlooked in this plant, even if very numerous. In the cycla- 

 men also the galls are small, but larger than in the violet. In the 

 rose they seem to vary somewhat in different varieties, but are mostly 

 of small size, especially on the smaller roots. On the main root they 

 become larger and one correspondent writes that he has seen them as 

 large as a duck's egg. This is an unusual size on any plant and 

 must have been the result of a growth of considerable time. In the 

 cucumber and tomato the galls are quite large and very prominent. 

 Besides the formation of root galls the nematode attacks are indicated 

 by the effect upon the vitality of the plant, though this effect is not 

 particularly definite or characteristic. In very badly affected soil 

 plants may be killed or very much stunted before reaching any con- 

 siderable size. The tomato and cucumber seedlings shown in plate 

 VII., figs. 3 and 4, were grown in such soil and never reached 

 any considerable size. Only in extreme cases, however, is the soil 

 as full of worms as this was, and more frequently the plants grow 

 normally at first, but after reaching a considerable size begin to 

 appear sickly. The leaves die at the edges, the plant stops growing 

 and gradually fades away or sometimes collapses quite suddenly. 

 The cucumber is perhaps the most liable to be killed outright, while 

 roses, violets, etc., often linger for a considerable time, although 

 this depends largely upon how badly the soil is infested. If the 

 worms are abundant when the plants are first started their attacks 



