550 
On the Fairrj-nngs of Pastures. 
cul.irly favourable to the growth of the grass which followed them. It 
may easily be seen that this explanation is abundantly sufficient for 
every circumstance of the case, if the theory of DecandoHe as to the ex- 
cretions of plants -were generally tenable. 
It is needless for me to remark, however, that this tlieory has been 
abandoned by most vegetable physiologists, and has lately met distinct 
confutation from the laborious investigations undertaken by Dr. Daubeny 
on the rationale of the rotation of crops. It becomes then necessary to 
seek some other explanation for the formation of the fairy-rings. In the 
spring of this year it occurred to me to make a chemical examination of 
these fungi, with the hope of throwing light upon their peculiar growth ; 
and I was favoured with an excellent opportunity of making this exa- 
mination upon several magnificent rings growing on the pasture land 
surrounding our College. 
My friend and colleague, Mr. Woodward, has furnished me with the 
following botanical description of the Agarics : — The Agarics were 
not the small Fairy-ring Agarics {A. Oreades) which usually occur 
under such circumstances, but a much larger species attaining a dia- 
meter of from 4 to 6 inches, and having a thick solid stem and top. 
The Agarics when fresh are nearly while, turning brown gradually as 
they approach the period of decay ; they are brittle, have no juice, and 
are nearly tasteless. A sketch which was sent (through the secretary of 
the London Botanical Society) to the Rev. M. J. Berkeley, was re- 
turned with the following memorandum : — ' This is the true St. George's 
Agaric of Clusius, or at least nearly allied to it — Agaricus graveolens. 
Sow.' (A. fastibilis, Pers.) It ajipears to be as famous for producing 
Fairy-rings on the Continent as with us." 
The fungi were gathered early in the month of May, after two or 
three dry days. Two of them, one large, the other small, were dried at 
a water-bath heat. They contained 
87'46 per cent, water, 
12"54 per cent, dry matter. 
8 or 9 lbs. of fungi were burned, and yielded an ash which attracted 
moisture with great avidity from the air. 
The quantity of ash yielded by the wwdried fungus was 0 80 per 
cent., or, calculated on the dry weight, 6'38 per cent. 
The analysis of the ash gave for its composition 
Ash of Fungus. 
Silica 
1 
•09 
Lime 
!• 
35 
Magnesia 
2' 
20 
Peroxide of Iron 
trace. 
Piiosi)horic 7\cid 
29 • 
49 
Sulphuric Acid 
I 
•9;] 
Carbonic Acid 
3 
•80 
Potash . 
55 
•10 
Soda 
3 
•32 
Chloride Sodium 
0 
•41 
98-69 
