RUSTS. 117 



above-named, that we can hardly believe any one 

 to have had a branch of either in his hand and net 

 observed it, provided any leaves adorned the branch 

 in question. What this parasite is, and what its 

 associates, it is our province to endeavour to ex- 

 plain. Our figure (plate VIII. fig. 160) represents 

 a leaf of the sallow or goat-willow, with the under 

 surface exhibiting yellow patches, consisting of 

 spores, which are magnified in the next figure 

 (plate VIII. fig. 161). This exceedingly common 

 rust is termed Lecythea caprearum, Lev., when in 

 the condition figured ; but in reality this is only the 

 summer stage, bearing the summer fruit of Melam- 

 psora salicina, which latter attains its mature 

 development on the same leaves in the succeeding 

 winter (plate IX. fig. 191) or early spring. Of 

 course this latter remark applies to the fallen leaves, 

 for at this period all the willows and other deciduous 

 trees are bare. But the leaves, before they fall, 

 give evidence of the parasite at work ; and if the 

 collected decaying mass of rubbish at the base of 

 sallow bushes be examined about March, these 

 leaves will be found bearing upon them mature 

 heaps of elongated, wedge-shaped spores, closely 

 packed side by side (plate IX. fig. 192), and which, 

 whilst still adherent, may often be found in active 

 germination, as represented in an allied species at 

 the bottom of our plate (plate IX. fig. 197). This 

 phenomenon consists in the production of cylindri- 

 cal tubes, more or less elongated, from the upper 



