BOTANICAL STUOLLS, 09 



and am of opinion that the variations observed are to be charged more to 

 the circumstances in which it is found, than to a generic or even specific difference. 



It is by no means clear, however, that the Vinegar- plant is invariably 

 produced by the same genus. Dr. Balfour found that the common blue 

 mould produced itj and it is well known that blue mould is the Aspergillus 

 gJaucus; indeed we might almost conceive of the mass being formed by as 

 many individuals and species as the gi'a^sy sward we tread on. That the 

 gelatinous body is formed by the interlacing of the root-like mycelium there 

 can be very little doubt, as will be seen on referring to the plant as grown 

 in the dry air. Fig. 7, where it will be seen that the tubes lie very closely 

 over each otlier. Suppose then these tvibes produced in greater quantity, 

 they would natitrally foi-m a soft spongy mass, which, if placed in a solution 

 nearly identical with it in chemical composition, would become consolidated 

 by the agglutination of the individual tubes, and thus form the tough 

 leathery Vinegar-plant. 



Tidking of its chemical composition. Professor Penny, of Glasgow, suggested 

 to me the idea of testing the plant for nitrogen, a gas well known to be 

 abundantly present in Fungi of the larger kinds; and which, if present, 

 must have been obtained from the air, being wanting in the synip. On burninfT 

 the plant I was ahnod convinced of its presence by smell, but could not be 

 certain. If Dr. Penny should find by experiment that nitrogen was really 

 present in any quantity, it will go far to explode the notion that the organic 

 constituents of plants are obtained essentially from the soil. In the case of 

 the larger Fungi, as Agarics, which contain a large quantity of nitrogen, the 

 soil in which they grow may be naturally looked to as its source, seeing 

 that many of them only grow on dung- heaps or rich pastures, 



Edinhurgh. 



BOTANICAL STROLLS IN THE NEIGHBOURHOOD 

 OF PLYMOUTH. 



NO. IV. 



Ok June 18th., in company with two friends totally unacquainted with 

 botany, but in whom I awakened an interest in the study as we proceeded, 

 I strolled to Wembury, a scattered village lying near the sea, between Plymouth 

 Sound and the mouth of the Yealm; but on this occasion did not go fir 

 beyond Langdon Hall, the seat of C. B. Calmady, Esq. As previously remarked, 

 it is my desire to name only such plants as I have not met with before 

 during my rambles in I80I; so that it must not be supposed that the few 

 enumerated are all that were observed; and I must beg excuse if any are 

 mentioned more than once, as memory may fail me. 



Our route from Plymouth lay over Catdown, where I found Hieraciitm 

 Pilosella, (Mouse-ear Hawkweed;) Sednm acre, (Yellow Stonecrop, or Wall 



