41 



Lead . In conparison with CuCNCjio ^^^ nitrate of 

 lead is considerably less toxic toward spores of Gloeosporiuni, 

 The concentration inhibiting germination after 18 hours 

 was found to be about O.C04m . "Yith a concentration 

 0.0C2m some of the spores showed slight local swellings on 

 the sides or ends. At this concentration spores were fre- 

 quently found in which one half was brown or blackened 

 while the other seemed devoid of protoplasm, appearing as 

 if the protoplasmic contents had all collected in one end 

 and had then taken on a thicker wall. No increase in size 

 or local swelling was apparent in such cases. In a concen- 

 tration of C.CClm the blackened bodies just mentioned were 

 found, as well ss swellings and also definite outgrowths 

 from one or both ends of the spore. The latter (shown 

 in Fig. 3 ) are of particular interest and require some 

 attention here* They are spherical in shape, dark brown or 

 black in color and appear in all respects similar to the 

 chlamydospores which have bean frequently described as re- 

 sulting from the germination, under certain special cond- 

 itions, of spores of various Gloeosporium forms. 



Appressoria have been described by Hasselbring ■^'^ 

 as forming when nutrient materials are absent and when 

 germinating apores or germ tubes come in contact with such 

 'hard surfaces as are furnished by the cover glass in a 



Hasselbring, H., The appressoria of Anthracnoses . Bot. 

 Gaz. 42:135-142. 1906. 



