﻿AS AFFECTED BY FUNGI 575 



patches of Cystopus bliti (Biv.) each nearly a third of an inch in 

 diameter was placed in the iodine solution without the previous 

 bleaching, when, after a week, it was found that practically no 

 starch was in the pustular portion, but close around the dis- 

 eased area was a deep blue circle. All the healthy portion of the 

 leaf contained starch in considerable quantity, but the large 

 amounts in the tissue immediately bordering the portion bearing 

 the conidia of the fungus were in striking contrast with all other 

 parts. 



The most striking subject among the leaf parasites is the man- 

 drake leaf infested with Puccinia podophylli Schw. It is inter- 

 esting for the very large amounts of starch that are located in the 

 infested areas, and also for the sharp line of demarcation between 

 the diseased and the healthy portions of the leaf. In other words 

 the Puccinia seems to find the ultimate ramifications of the vascu- 

 lar system a complete barrier to its lateral growth, and it seems 

 that the infection in many instances is local and does not reach be- 

 yond the angular boundaries made by the smaller veins. The 

 same lines become the enclosures for the starch-bearing areas. 



It will also be seen here that the infested areas bear some rela- 

 tionship to the main veins in this, that one side at least of nearly 

 every infested area is against a vein of considerable size, a subject 



that is a study in itself. 



Another fact is noticed in the mandrake, namely, that as a 

 rule there is less starch in the center of the rusted mesh than 



nearer the periphery. 



One of the most striking instances of starch localization is 



found in the leaves of ordinary corn that are infested with the smut 

 (Ustilago maydis DC). Pieces of leaves that were more or less 

 distorted by nodules and projections of the smut-bearing tissue 

 that had been in alcohol for a year as material for class study of 

 the smut were placed in the iodine, when the blue color began 

 almost immediately to appear in the swollen tissue. All of the 

 bullate portions of the leaves due to the infestation of the fungus 



became 



A 



there was an abundance of starch in the warts, around each center 

 there was a very small space free from starch followed by the 



