504 PROCEEDINGS OF THE ACADEMY OF [May, 



Fig. 24.— Section of stem diseased by the presence of fungus, Qynmo- 

 sporangium ElUsii. The course of the hyphse from tracheid to tracheid 

 is shown. The hyphse in several places are seen to grow through the 

 bordered pits. 



Fig. 24a. — Course of a hypha which grows through the bordered pits. 

 Notice that the hyphae become lens-shaped in the cavity of the bordered 

 pit. G. Mlisii. 



Fig. 25. — Hyplia enlarged, showing the nodose or ventricose enlarge- 

 ment of the fungal cells. Q. ElUsii. 



Fig. 26.— Details of hypha of G. ElUsii. 



Fig. 27.— The same from the wood. 



Fig. 28. — Bent and twisted hyphae growing in the brown areas of 

 broken-down tissue, as shown also in fig. 29. 



Fig. 29. — Spores (several forms) ol Gymnosporanqium biseptatum 

 (after Tubeuf). 



Fig. 30.— Spores (uni- and multicellular) of G. ElUsii (after Tubeuf). 



Fig. 31. — Transverse section of diseased white cedar stem, showing 

 the diseased brown areas in the wood which have become more or less 

 confluent. 



Fig. 32. — Tracheids from diseased wood of white cedar, showing the 

 sprung lignified cell wall. 



_ Fig. 33.— Commencement of brown wedge-shaped areas of diseased 

 tissue. Notice the abnormal size of the cells filled with granular matter. 



