106 JOURNAL OF THE 



origin through the irritating presence of animals.* These nem- 

 atode root-o-alls would belono; to the same class of abnormal 

 growtiis sometimes denominated HehninthoceckUen. The writer 

 does not mean by the use of the term root-gall that it has })rior- 

 ity to the use of the term root-knot, but in view of the appro- 

 priateness of the word, teratologioally, and for the reason stated 

 above, he would recommend its adoption. 



External Characters. — For the purpose of preparing the 

 reader for a study of the life history and transformations of the 

 parasite, section II was introduced, in which attentinn was called 

 to the general external morphological characters of the galls in a 

 few plants. It is now in order to discuss more at length the 

 variations in form of the galls, and then to point out the special 

 histological changes induced. 



The external form of the gall is to a great extent dependent 

 upon the number of worms and their distribution in the tissues 

 of the roots, as w^ell as upon some specific peculiarities in the 

 p:rowth of the roots or habit of branchino:. If the worms are 

 numerous and the attack is made pretty regularly in a peripheral 

 plane at a particular point in the root the gall will be symmet- 

 rical, and either short and ovoid or eh^ngate and fusiform, 

 accordino: to the extent of their distribution alono- the axis of 

 the root at that point. If fewer worms attack at a given point 

 the gall is more likely to be lateral, owing to the less certainty 

 of an even peripheral infection. Often, however, lateral galls 

 may be so near as to unite into one, when the appearance is that 

 of a very irregular and knotty gall, the enlargements passing by 

 abrubt changes on different sides of the root. 



For the forms of the galls in the roots of the tomato, potato 

 and peach tlie reader is referred to Section II. 



The galls found in the "poke- weed '^ (Phytolacca dccandra) 

 were very large, lateral and ovoid. In a species of the })lant 

 called coffee weed [Cassia obtusifolla) lateral galls were found on 

 the tap r(K)t near the surface of the ground. On the grape the 



*Soraner, Pflanzenkrankheiten, Zweite Aiittage, Heft, I. 



