494 PROCEEDINGS OF THE ACADEMY OF [^laj, 



correspondingly iu thickne.ss, and maintaiued for some time a slow 

 growth through the wood and medullary ray cells. 



We have these changes iu the structure and metabolism of the 

 cells of white cedar paralleled by examples recorded by other 

 botanists. Halsted'-'* states that " one of the most striking instances 

 of starch localization is found in the leaves of ordinary corn that 

 are infested with the smut (Udllago maydis D.C. ). Pieces of 

 leaves that were more or less distorted by nodules and projections of 

 the smut-bearing tissue .... were placed in the iodine, when 

 the blue color began almost immediately to appear iu the swollen 

 tissue. ' ' Again : ' ' An interesting study in this direction was 

 made of the cedar galls of Gymnosjjoranglwn macropus Lk., where 

 the starch is packed away in the enlarged host cells to their utmost 

 capacity, and thin sections through the centres of the large galls 

 display a neat fan -shaped appearance after they had been in iodine 

 for a few minutes. The ordinary wood of the gall-bearing twigs 

 show with the same treatment only a small amount of starch." 

 Other cases of this influence of parasite upon host might be cited, 

 but the illustrations mentioned above sufficiently show that in most 

 instances the effect is a marked one, not only altering the chemical 

 nature of the cell contents, but also the activity of the process of 

 cell division with the formation of additional tissue elements. 



Tabular Comparison of the Several Species op the 

 Genus Gymnosporangium. 



Iu the table on pages 498-501 an attempt is made to pi-esent the 

 characters of the several species of the genus Gymnosporangium, so 

 that a comparison of the structure of these fungi can readily be 

 made. 



Summary. 



1. The v/hite cedar, Cujiressus thyoides, is a stately tree, ranging 

 from southern Maine to northern Florida and westward to IMissis- 

 sippi, and is not subject to any very serious disease. 



2. There are nineteeu species of fungi that live, saprophytically 

 or parasitical ly, upon this tree. 



-^ Halsted, Starch Distribution as Aftected by Fungi, Bulletin of 

 the Tovrey Botanical Club, XXV, p. 573. 



