28 ATLAS DER DIATOMACEENKUNDE. 



request in the names also of those who hope and expect that the 

 publication of my * Atlas' -will greatly advance the knowledge of 

 the Diatomacese, and their number is, I am happy to say, no small 

 one." 



F. KiTToN, Norwich. 



ON THE FRUCTIFICATION OF RHYTISMA 

 MAXIMUM, Fries. 



The polymorphism of fungi is one of the most interesting and 

 important subjects the mycologist has to study, bearing as it does, 

 not only upon the reproduction, but also,now-a-days, upon the classi- 

 fication of these organisms. Personally, we are inclined to think 

 too much use is made by some mycolographers of the secondary 

 forms of fructification, in their endeavours to find characters for 

 the differentiation of genera, but this is far too extensive a subject 

 for discussion here. 



The following observations upon the fructification of Ehytisma 

 maximum, Fr,, may be interesting, as the plant itself does not seem 

 to be one of very common occurrence in this country ; they have 

 been made upon specimens, gathered at various seasons, which 

 grew parasitically on some young willows in a clay pit near King's 

 Lynn. 



We believe that Sowerby's Sphceria aurea, t. 356, and Greville's 

 Cryptomyces wauchii, t. 206, represent this plant, the former de- 

 picting it in its earlier conditions, the latter representing the 

 ascigerous state, for according to our observations the golden 

 yellow border, though not always absent, is far less marked in the 

 ascigerous than in the non-ascigerous plant. 



Usually, however, the first manifestation of the parasite consists 

 in a yellow discoloration of the outer bark of some of the younger 

 branches. Frequently these discolorations are elongated in form, 

 but whether so or not, in their centre are soon observable one or 

 more black spots or patches, varying in size from a line or less to 

 several inches in length. Repeated examinations of the fungus 

 in this stage have failed to reveal any fructification whatever, and 

 indeed very little structure at all. One of two things now happen, 

 either the whole fungus, and more particularly the black central 

 portions, increase in extent and thickness, without however mani- 

 festing any particular microscopic structure, remain for a longer or 

 shorter period in a state of quiescence, and then develope asci and 

 sporidia : presently more particularly to be described. Or, as not 

 unfrequently happens, the blackened patches become distended by 

 a semi-turbid fluid, forming so many distinct blisters. The fluid 

 which they contain owes its turbidity to a host of minute hyaline 

 more or less oval spermatia, averaging about -OOOlin. across, t. 63, 

 fig. 6. We have never seen these bodies borne upon sterigmata as 

 figured by Tulasne t. xvi., fig. 4. In this stage the plant is not 



