be caused to plants by other organisms of various kinds, among which 

 the nematode worms are probably the most important. 

 What Nematodes Are. 

 The Nematodes or Nematode Worms form a class of animals 

 grouped under the Vermes or true w orms. They are much lower in 

 the scale than the larvae or caterpillars of insects, which are popu- 

 larly known as worms and often cause injuries to plants, and are 

 lower also than the earthworm, which is one of the most highly 

 developed of the Vermes. The nematodes vary greatly in size, 

 shape, and manner of life and include many peculiar and remarkable 

 forms. Most of them however have at some period of their exist- 

 ence an elongated worm-like form, whence the popular names eel worm, 

 thread worm, etc. Some keep this form during their whole existence 

 and live in water, earth, decaying matter, and other damp places. 

 Most of them are entirely harmless to plants and animals. They 

 are usually of very small size, scarcely or not at all visible to the 

 naked eye. Many different species of this kind exist abundantly in 

 Nature. The well known "vinegar eel " is an example. A great 

 number of nematodes however live for all or part of their lives as 

 parasites; many on animals and a few on plants. Such forms pass 

 through many most remarkable changes in their development. The 

 Trichina of pork and many other animal and human-infesting worms 

 are nematodes, while the tape worm, liver fluke, and in fact almost 

 all organisms of that nature are closely related. The so-called hair- 

 snake is a nematode, much larger than most kinds. In relation to 

 plants, we have to consider, in this locality only a few, and, as far as 

 we know, but one species of nematode. We know of no other 

 among the many indigenous to our soil capable of causing any con- 

 siderable injury to plants. All such trouble is due primarily to the 

 one species, Heterodera radicola, (Greet.) Miill. There is a more 

 or less prevalent idea that all kinds of nematodes cause injuries to 

 plants, but such is certainly not the case. The soil may swarm 

 with nematodes but, if our observations are correct, unless there 

 are among them this one species no injury will result. 



Symptoms Of Nematode Injuries. 



The only definite indication of the attacks of Heterodera radicola 

 is found in the roots of affected plants. These are more or less 

 covered with what we shall call galls, that is swellings or 



