1902.] NATURAL SCIENCES OF PHILADELPHIA. 489 



tracheitis will have hyphse coursing through them, and occasionally 

 two or three hyphte are met with in a single tracheidal cavil y. 

 Where these hyphse, ' by branching, cross transversely other 

 tracheids, they are observed in cross-sections of stem as short 

 threads, or as U-shaped or V-shaped elements of a purplish-brown 

 color. Whenever these hyphse in their branching enter one of the 

 brown areas with cleft-like cavities, they grow through the brown 

 mass, enlarging meanwhile in diameter, and grow out into the cleft, 

 where they branch and rebranch in an irregular manner, swelling 

 here and there into the nodose or veutricose cells referred to above 

 (fig. 27). Occasionally the hyphie are found growing outwai'd 

 through the medullary ray cells, but this seems to be the exce])tion 

 rather than the rule. This fact affords another of the characters of 

 the mycelium of G. Ellisil which differentiates it from that of G. 

 biseptatum, also found on the white cedar. 



The distribution of the tracheids containing the hyphte, disposed 

 as above described, is for a transverse section of stem seven years 

 of age, as given in the accompanying table. The number of 

 tracheids in which hyphse are found is estimated for one-half of 

 each annual ring. The widest annual ring is that of the third 

 year, and this increased width is closely correlated with the diseased 

 condition of the stem for that year : 



Table V. 



The brown areas are by far the largest and almost confluent in 

 the third annual ring of wood, and therefore only four continuous 

 radial strips of healthy xylem are to be found in the growth of the 

 third year. The enumeration for the seventh year is incomplete, 



