158 MICROSCOPIC FUNGI. 



general with tlie former as the latter ; but in some 

 districts it has been far from uncommon. 



The fertile threads are collected in bundles, erect, 

 and not so much branched as in many other species. 

 The acrospores are sub-globose or ovoid, and 

 papillate at their apices. This species is sometimes 

 called P. iimhelUferarum, and sometimes P. macro- 

 sj>ora. Generally speaking the average humidity 

 of a season but little affects the production of 

 parasitic fungi. In a dry season, hke that of 1864, 

 we found as many species, and these as flourishing^ 

 and numerous in individuals, as in a proverbially 

 wet year. Such is not the case, however, with the 

 moulds under notice, or such fungi as are repro- 

 duced through the medium of zoospores : these are 

 undoubtedly less common in a very dry season; 

 but it must be remembered that a single shower is 

 sufficient for the development of zoospores, and 

 occasional showers or heavy dews will speed them 

 on their course of destruction as readily almost as 

 continuous moisture. The large fungi, on the 

 contrary, become very limited in numbers when the 

 weather is unusually dry. 



Spinach Mould. — Spinach is hkewise hable to 

 suffer from the establishment of a mould upon the 

 under surface of the leaves : unfortunately this is 

 not unfrequent, and has been known in England 

 certainly for the last fifty or sixty years, since it 

 was figured by Sowerby in his "British Fungi" 

 as many years since. We have lately seen a bed 



