Conoplwlis avuiicaiia. 7 



lis. It has also tlie two bracts. According to Chatin, there 

 is a close correspondence in the pecuhar histological charac- 

 teristics of the two genera. He figures for both the same 

 arrangement of bundles, and the same kinds and distribution 

 of parenchyma. 



This seems to indicate that these two genera certainly, 

 and possibly Apliyllon also, might be better included as 

 species of a single genus. Unfortunately, as I shall show- 

 later, no reliance can be placed on Chatin's work. 



V. The Host Plant. 



The host of C. avicricana is given by Gray as the oak. 

 Dr. Thomas Porter gives the same observation, as do the fol- 

 lowing : P. H. Rolfs, L. C. Corbett and W. W. Ashe. Mr. 

 Albert Norris reports to have seen it in two cases under maple 

 trees, and Rolfs reports it under oaks and beeches. In all 

 cases, where the parasite has been traced to its attachment, it 

 has been invariably found to be parasitic on the oak. It is, 

 however, frequently quite a distance from the trunk of its 

 host, which may account for its being found under other 

 trees. There is no positive evidence in favor of any other 

 than an oak attachment. 



VI. Duration of Life. 



The flowering shoots are undoubtedly of annual develop- 

 ment, probably from buds formed the previous year in tuber- 

 cles whose length of life must depend upon the capacity of 

 the host to feed the parasite. 



It was impossible to determine accurately the age of the 

 tubercle. The relationship between its size and the age of 

 the oak root was the only clue that I could get of the age of 

 the parasite. Tubercles half an inch in diameter, with small 

 buds which had apparently just pierced the cortex, were found 

 on roots three and four years old. The oak root, whose 

 photograph is shown in Plates I and II, is fully eleven years 



