70 THE AMERICAN MONTHLY [Mar 



they enacted a law requiring people to destroy their bar- 

 berry bushes as a protection to wheat fields, but they did 

 not understand why. The English farmers had the same 

 suspicion and fortunately acted upon it. 



The fungus, Uromyces pisi, as its name implies is a pest 

 to pea-growers. It belongs to the Uredinea family, a 

 group of 500 parasitic fungi. It lives parasitic on the 

 spurge, Euphorbia cyparissias, and also on thB leaf of the 

 common pea, Pisum sativum, going through five difi'er- 

 ent spore relations which is the maximum number known 

 to science. 



The secidia or "Cluster-Cups" of certain fungi are high- 

 ly esteemed as opaque objects to be viewed by reflected 

 light or in sections under the microscope, being very beau- 

 tiful and interesting. The spores can be germinated in 

 cold water containing one per cent of cane sugar. They 

 should be mounted in glycerine jelly after having been 

 soaked in glacial acetic acid to prevent shrinkage. 



The effect upon the spurge plant resulting from carry- 

 ing the fungus mentioned is striking and extraordinary. 

 Examine figure 1 in the frontispiece and you will see 

 that the healthy spurge is large and vigorous. It has 

 thin, linear, and somewhat deep-green thick-set leaves, 

 seven to fourteen times as long as broad. The infected 

 spurge is shown in figure 2, with short, thick leaves 

 which are wide apart, dusty yellow in color, only four 

 times as long as broad. The stems are naked, stalky and 

 unbranched. The floral organs are aborted and sterile. 

 These two plants differ in color, tissue, habits and appear- 

 ance so that they would hardly be recognized as of the 

 same genus. The attack of the parasite causes elonga- 

 tion of the stem and shortening and thickening of the 

 leaves. Figure 3 shows an enlarged leaf dotted with 

 aecidia. There are usually about 50 aecidia to each leaf. 

 They are about one-third of a millimeter in diameter and 

 each contains some 250,000 spores ?ach capable of inocu- 



