Queries and Answers. 739 



colour is displaced by a dark brown one, betokening the leaf as dead or 

 dying in this part, and within the brown part, on the surface of the leaf, 

 are orangy blotches, and from these blotches, on the under side, protrude 

 softly woody excrescences, from which are projected pale brown teat-like 

 miniature bags, more than a quarter of an inch long, and closed at the 

 mouth. These bags are the peridia of a parasitic species of fungus 

 belonging to the genus iEcidium : although, to strictly accord with the cha- 

 racters of this genus, they should have an orifice, usually lacerated, at the 

 tip. In p. 179. of the present Volume will be found (in extracts from the 

 Memoirs of the Caledonian Horticultural Society) a very interesting descrip- 

 tion, by the late Mr. Wm. Don of the Hull Botanic Garden, of the iEcidium 

 laceratum, and of the manner in which a,hawthorn hedge round the Hull 

 Botanic Garden was infested with it. This pretty species, the iEcidium 

 laceratum, we have had the pleasure of seeing this autumn, although but 

 sparingly, on the fruits and foliage of an old hawthorn hedge at Bays- 

 water. | This species will be found well figured in the Encyclopedia of 

 Plants, p. 1045., No. 16677. 



In Mr. Don's account, already referred to, it is incidentally remarked 

 that the " iEcidium cancellatum of Sowerby's English Fungi, t. 409., 

 attacks pear trees, and often prevents valuable crops." This remark has 

 induced us to submit the specimens, sent by Mr. Merrick, to Mr. J. D. C. 

 Sowerby, who has kindly informed us that they are of the M. cancellatum, 

 and that it is one of the characteristics of this species, to have the peridia 

 devoid of an orifice at the tip. 



Those whom this notice of the genus iEcidium may render desirous to 

 know more about it will find twenty species of it described, and some of 

 them figured, in the Encyclopaedia of Plants, p. 1044 — 1046.; and in this 

 Magazine there are notices of two or three species, in Vol. III. p. 382. 490, 

 491., Vol. IV. p. 192., Vol. VII. p. 599., and Vol. VIII. p. 179. 



The peridia, or teat-like bags, already spoken of, are seed bags enclosing 

 the seeds, technically called sporidia ; and hence it may be, that when the 

 leaves of a tree have become diseased, so as to be eligible soil, as it were, 

 for the seeds or sporidia of the iEcidium, that these, on falling on them, 

 may germinate readily, and occasion that numerous and extensive multipli- 

 cation of the fungus of which Mr. Merrick, with much cause, complains. 

 This idea of iEcidium growing from seeds scattered on the surface of dis- 

 eased leaves scarcely comports with one of the botanical characters of the 

 genus, which is, that the peridium, or seed bag, is formed beneath the epi- 

 dermis of a leaf, and which it ruptures by its increasing size, and afterwards 

 projects beyond it. If the iEcidium is, however, after springing up on a 

 tree, multiplied by its seeds externally scattered, it is a question not 

 unworth occupying the mind with, whence arose the original plant or 

 plants ? They might be conveyed in the air from other districts where this 

 parasitic fungus prevails. But this question is asked, as much for the sake 

 of introducing the following speculation as for any other purpose : it is 

 offered by a distinguished contributor to the Magazine of Natural History, 

 Mr. Dovaston, in vol. v. p. 116. of that work. Notwithstanding theplenti- 

 fulness of fungi, we " very rarely find them without some visible (and 

 never perhaps without some latent) excitement : such as dung, combustion, 

 decomposing wood, or weeds ; indeed, the seeds of fungi are so absolutely 

 impalpable, that I have sometimes thought they are taken up with the 

 juices into the capillary tubes of all vegetables, and so appear, when decom- 

 position affords them a pabulum and excitement, on rotten wood and 

 leaves : and this seed is produced in such excessive quantities, thrown off 

 so freely, and borne about so easily, that perhaps there is hardly a particle 

 of matter whose surface is not imbued therewith ; and had these seeds the 

 power of germinating by mere wetness alone, without some other exciting 



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