442 Proceedings of the British Association. 



Sir John Johnstone observed, that the value of guano was supposed 

 to depend on the quantity of uric acid it contained : he begged to inquire 

 if any experimental evidence existed as to the qualities of this acid as 

 a stimulant or otherwise. — Prof. Liebig stated, that there was not a 

 single experiment on uric acid — that all which had been said as to its 

 advantages, was mere assumption. — Dr. Tilley made some remarks on 

 the fact, that the skin of the leg of a gull had been found by him in 

 guano, the entire bone of the leg being dissolved out ; seal skin had also 

 been found, but no bones. — Mr. Hunt stated, that of two cargoes of 

 African guano which arrived at Falmouth, one entire cargo consisted 

 of decomposed seals. In this he found the skin with the fur quite per- 

 fect, and a great number of bones far advanced in decomposition. It ap- 

 peared, on inquiry in various quarters, that half a century since the 

 seal fishery was carried on most extensively on that coast, the seals were 

 all taken to the shore, the oil extracted, and the remains thrown into 

 large heaps— thus, on this particular spot, had accumulated those immense 

 heaps, which they had been removing as the production of birds. Its 

 value as a manure was not less than that of true guano ; analysis giv- 

 ing very nearly the same results in the two samples examined by Mr. 

 Hunt from these ships. 



Saturday. 

 Section C— GEOLOGY AND PHYSICAL GEOGRAPHY. 

 'On the Microscopic Structure of Shells, &c.' by Dr. W. B. Carpenter. 

 — Dr. Carpenter gave an abstract of his Report on the microscopic 

 structure of recent and fossil shells, &c. He stated that, with the aid 

 of the grant last year voted to him by the Association, he had made 

 upwards of 1000 sections and other preparations of shell-structure; and 

 that, in many instances, he had examined the entire structure of shells, 

 which presented the most characteristic features, in order to anticipate 

 the objection that varieties of structure might exist in different parts of 

 the same individual. Dr. Carpenter then explained, with the aid of 

 a series of large coloured drawings, his views on the formation of shell. 

 In regard to the prismatic cellular structure, he pointed out a series of 

 striae, crossing the long prismatic cells ; and present also on the cal- 

 careous prisms (casts of the interior of these cells,) which may be ob- 

 tained by the disintegration or fossil Pinnae, and sometimes even from 

 recent shells. These striae he believed to indicate the points where a 

 series of flattened cells, arranged in a pile, had coalesced to form a 

 single long prismatic cell. He pointed to the alternation of deeply- 

 coloured and colourless strata, in a single layer of Pinna niyrina, as 



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