TEANSACTIONS OF THE SECTIONS. 147 



The. Biolofjlcal Results of a Cruise in H.M.S. * Valorous ' to Davis Strait in 

 1875. % J. Gwnr Jeffbets, LL.D., F.E.S. 



A preliminary Report on tliia subject was presented to the Royal Society, and 

 lias been published in their ' Proceeding's,' vol. xxv. p. 177. The author gave an 

 account of the voyage (which was undertaken by him in consequence of an applica- 

 tion made by the" Council of the Society to the Admiralty) and of the biological 

 results, more especially with respect to geographical distribution and geology. The 

 author treated of the Mollusca ; and Professors Allman and Duncan, Dr. M'Intosh, 

 the Rev. A. M. Norman, Dr. Carpenter, and Professor Dickie contributed notices 

 of other departments of the marine fauna and flora. 



A Double Dilemma in Darwinism. By the Rev. F. 0. Moeeis. 



N^otes on Oceanic Deposits and their Origin, based on Observations made on 

 board EJI.S. ' Challenger.' By John Muerat. 



On the new Cases in the Hunterian Museum. By Prof. J. Young, M.D. 



Anatomy and Phtsiologx. 



[For Dr. M'Kendrick's Address, see page 12G.] 



On the Development of the Proto-Vertebrce in Elasmohranchs. 

 By F. M. Balfour, B.A., Fdloiu of Trinity College, Cambridge. 



Tlie mesoblast in Elasmohranchs arises as two independent plates, each of which 

 becomes divided into two layers, a somatic and a splanchnic. In the dorsal part 

 of each plate a series of transverse slits arises, which serves to distinguish a dorsal or 

 vertebral portion of the plate from a ventral or parietal. A cavity is next formed 

 between the two layers of the plate, which is continued quite to the summit of the 

 vertebral part. Still later the segmented vertebral part of each plate, with its en- 

 closed cavity, becomes separated from the parietal part and forms the muscle-plates. 

 Each of these is a somewhat rectangular body, formed of two layers, enclosing 

 between them part of the original body-cavity. The inner of these two layers soon 

 buds off cells to form the rudiments of the vertebral bodies, and itself is trans- 

 formed into longitudinal muscles ; the outer layer of the muscle-plate becomes con- 

 verted into muscles at a considerably later period. 



On the Changes in the Circulation ivhich are induced when the Blood is expelled 

 from, the Limbs by Esmarch's Method. By H. G. Brooke, B.A. (Lond.), 

 and E. 0. Hopavood, BA. (Oxon). 



The authors stated that the object of the experiments was to observe the pulse 

 dm-ing and after the expulsion of 'blood from the limbs. Healthy young men were 

 experimented on, and the experiments were made one or two hours after a light 

 meal. The pulse was counted with the aid of a watch, and its form recorded by 

 means of the sphygmograph. The person experimented on was stripped and recum- 

 bent. Normal pulse-rate and sphygmographic movements were recorded ; and 

 afterwards one leg was bandaged from below upwards. During bandaging, pulse- 

 rate was observed, and immediately bandaging was complete further sphygmo- 

 gi-aphic tracings were taken. This was repeated with the other leg. After a short 

 time both bandages were suddenly let go, and at the same instant pulse-rate and 

 ephygmographic movements were again recorded. 



