326 FUNGI. [ErysipJie, 



arachnoid dirty-white at length forming spots, fulcra simple 

 acute deflexed, peridiola many. Lk. I. c. p. 105. Fr. Syst, 

 Myc. V. 3. p. 289.— 'E. Artemisia, Grev. Fl. Ed. p. 459.— £". 

 Lathyri, Robinice, Pisi, Arctii, Aquilegii, Alchemillce, Asperi- 

 fQlioriim, Ranunculi, ejusd. I. c. p. 460, 461. — E. 9iitida, Baxt. ! 

 Ox. n. 91. ^E. Pisi, Grev. Scot. Crypt. Fl. t. 134. 



On various herbaceous plants. Extremely common. — A slightly dif- 

 ferent form occurs on almost every herbaceous plant, nor are the pecu- 

 liar forms confined to plants belonging to the same Natural Orders. It 

 seems to me quite superfluous to give a detailed account of all which 

 have hitherto occurred in this country. Fries appears to have very 

 judiciously reduced the various cognate species of authors to Ery- 

 sipke communis. Nothing can be more easy than the mere collec- 

 tion of individuals and classifying them according to the names of the 

 plants on which they are found ; but after the main groupes of the genus 

 have been determined, distinguished by marked diversity of structure, 

 each of which abounds in varieties differing slightly according to the 

 more or less succulent nature of the matrix, it is a matter of the utmost 

 difficulty, if not altogether hopeless, to refer those slightly different 

 forms to the species which may be proposed by authors, who consider 

 every form a species, except, as said above, the mere name of the plant 

 give the clue and be considered as decisive. Or indeed, where a higher 

 object is aimed at, and it is endeavoured to arrange the multudinous 

 varieties, under something deserving the name of a species, does there 

 appear to me much less uncertainty, when the changes which take place 

 at the several periods of growth are called to mind, and convinced as I am 

 that all such will be soon found fallible from the constant occurrence 

 of intermediate states. It maybe well to take the present opportunity 

 of making a remark upon the genera JEcidium, Uredo, and Puccinia, 

 as they labour under the same inconvenience of ill defined species. 

 Though much study has been devoted by various persons to the subject, 

 nothing comparatively has been done towards the establishment of certain 

 species. Link has attempted something in Mcidium, but I think un- 

 successfully ; indeed he does not appear himself to be satisfied, and he 

 arranges the species, as in the other two genera, according to the Natural 

 Orders of the plants on which they grow. In Uredo and Puccinia there 

 are very striking discrepancies in the forms of the sporidia, which at 

 present there is no reason to believe dependant on the peculiar matrix, 

 and there is therefore in general, under the present state of knowledge, 

 no possibility of avoiding assigning a distinct species to each plant, or 

 at any rate to each natural order. And, in consequence, as the species 

 are of course determined with the greatest ease and without any study, 

 there is a great temptation to beginners in Mycology to pay attention 

 at first to such plants, to the neglect of those whose determination is 

 attended with more difficulty, and hence too often a loose and empiri- 

 cal mode of examination is acquired. Fries in his Systema has many 

 remarks to the same effect, but I think that as regards the three last 

 mentioned genera he has run into the opposite extreme ; except indeed 

 it be borne in mind that according to his theory, which I believe to be 

 quite untenable, they be regarded as mere " anamorphoses" of the cel- 

 lular tissue of plants. The numerous species found by Dr. Greville 

 about Edinburgh are admirably treated in the Flora Edinensis. The 

 present genus he has confessedly not studied so much, and I therefore 



