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species of trees along the line of the railroad in passing 

 from one geological formation to another. Each deposit 

 seemed to have its own species. He thought the natural 

 productions of the surface had not been sufficiently dwelt 

 upon by geologists as illustrating the character of particular 

 formations. 



Dr. Burnett presented the results of his observations on 

 the phenomena of muscular contraction. 



It was Haller's doctrine, that muscular fibre is capable of 

 contraction without the aid of the nervous system. More recent 

 anatomists had thought that it must be due to nervous influence, 

 even when communication with the nervous system had been 

 cut off. Bowman had seen a single fibre, when detached from 

 the nervous system, contract backwards and forwards. Within 

 the past year he had himself observed this phenomenon several 

 times. He considered this a sufficient proof that muscular tissue 

 has a contractile power of its own, distinct from that under the 

 influence of the nervous centres. It had been observed that 

 muscles, in contracting, lose none of their volume. In examining 

 the tentacular muscle of Alcyonella with the microscope, he had 

 found it to be a simple tube, containing numerous grains, at short 

 distances from each other. In contracting, the muscles short- 

 ened one half. At this time the granules were seen to touch 

 each other ; and it would thus appear that the essential element 

 of muscular contraction is a sudden increase of cohesion among 

 the granules, or rather utricles, of the ultimate muscular fibrilla. 

 What is the force which suddenly attracts the granules to each 

 other does not appear. 



Dr. Burnett alluded to the motion of Spermatozoa, about which 

 there has heretofore been so much obscurity. On examining 

 them under a high power, treated with acetic acid, he had found 

 them to be made up of utricles, which in the tail are arranged 

 in a single line. The motion begins in the head of the sperma- 

 tozon, and is continued to the tail. It would seem probable 

 that it is due to the same cause as that which produces muscular 

 contraction, namely, utricular action. 



Mr. Ayres remarked, that recent observations upon 



