1902.] NATURAL SCIENCES OF PHILADELPHIA. 495 



3. Oiily two species of fungi, viz., Gymnosporangium hisep- 

 tatum Ellis and G. EUisil Berk., may be considered as serious 

 parasites. 



4. Historically these two funguses have been studied largely 

 from a moi'phologic standpoint, and not from a physiologic or his- 

 tologic point Df view. 



5. Wornle and Tubeuf give the most satisfactory accounts of 

 the several known species of GijmiwsporatKjlum and the diseases 

 produced by them. 



6. The two diseases are prevalent in the cedar swamps of New 

 Jersey, where Cupressus thyoides makes an almost pure stand of 

 timber. 



7. Sections of the swellings caused by the fungi were made by 

 means of a hand-plane and stained with aniline-green, Bismarck- 

 brown, and a double stain consisting of methyl-green and acid- 

 fuchsiu. 



8. The swellings produced by Gymnosporangium bisepiatum a?-e 

 usually nodose, increasing year by year, until they may be brain - 

 like in appearance and six to eight inches in diameter. 



9. Those produced by G. Ellisil are never so thick, but the 

 branches involved radiate out in a fan -like manner, assuming the 

 character and appearance of witches' brooms. 



10. The normal stem structure is described as a means of throw- 

 ing light upon the abnormal structures produced by the fungi. 



11. The stem structure in general is that common to other coni- 

 fers, but the resin canals are confined to the bast and cortex. 



12. The number of tracheids produced normally in a radial line 

 are set forth in tabular form, as an expression of the variation in 

 size of the several annual rings. 



13. The environmental conditions are shown to have considerable 

 influence in determining the spread of the diseases. 



14. Sphagnum bogs are cold because the winter cold persists well 

 on into the summer. 



lo. This persistence of the winter cold retards the dcvelo[)ment 

 of the tree each year until summer is well advanced, and this 

 retardation, it is thought, is reflected in the uniformity in size of 

 the tracheids, there being litlk' well-marked autumn wood. 



