ELISHA MITCHELL SCIENTIP^IC SOCIETY. 127 



Tkapping the Worms. — In Germanv cultivators of the 

 sugMr-l)eet have resorted, witi) a degree of success, to trapping 

 the worms of a related species (H. ScJiachtii)'^ from badly infected 

 soils by the cultivation of plants very susceptible to the disease, 

 and then gathering the roots before the worms are fully developed 

 and destroying them. Such plants they call ''catch plants" 

 (" Fangpflauzen "). 



Composts. — If roots are ever used in the making of composts 

 great caution should l)e used, since there is danger of infecting 

 soil hitherto free from the worms by fertilizing such land with 

 compost material containing diseased roots. Kiihnf has shown 

 that such infection does take place in the case of a related species, 

 Heterodera Schachtii Schmidt, and also states that the material 

 may be rendered innocuous by placing unslacked lime in layers 

 with the infected refuse of plants which may be used in compost. 

 For distributions, see close of Section V. 



YIII. 



Plants Affected. 



The following list of plants aifected with the nematode root- 

 galls is by no means complete. It comprises only such as with 

 limited time I have been able to determine thus far in the vicin- 

 ity of Auburn. From the foregoing study and comparison of 

 the root-galls with externally similar teratological root growths 

 it will be seen that two essential characters must he determined 

 before in all cases we can say the abnorinal growth is a nema- 

 tode root-gall : a microscopic examination to detect the presence 

 of the worm and the histological changes accompanying its par- 

 asitism. Bi)th of these tests have been applied in making up 

 this partial list. Those marked with a * are badly affected : 



*Sorauer, Pflanzenkrankheiten, Vol. II, p. 854. 



fDie Ruben Nematode. Zeitschrift des landwirtlischaftlichea Central- Vereins der 

 Provinz Sachsen, No. 12, pp. 332—335, 1870. 



