34-2 



metamorphoses of a peculiar kind, and of a different character from 

 those of insects. Mr. Thompson's views are founded upon some cir- 

 cumstances which he has observed in certain animals of the genus 

 Zoea of Bosc, and which have been recorded by Professor Slabber, and 

 which have led Mr. Thompson to believe that, of these animals, some 

 were the young of the Cancer Pagnrus, or common crab, and others 

 the young of the Astacus Pagurus, or common lobster; and these views 

 are supposed by him to be corroborated by the annual peregrinations 

 of the land crabs to the sea-side, for the purpose of depositing their 

 eggs, rendered necessary by the aquatic habits and conformation of 

 the young. The author proceeds to examine at length the arguments 

 on which Mr. Thompson has founded these opinions, and adduces his 

 reasons for concluding that they are erroneous, and that no excep- 

 tion occurs to the general law of development in the Crustacea, 

 namely, that they undergo no change of form sufficiently marked to 

 warrant the application to them of the term metamorphosis. 



" Memoranda relating to a Theory of Sound." By Paul Cooper, 

 Esq. Communicated by J. G. Children, Esq., Sec. R.S. 



The author, expressing his dissatisfaction with the commonly re- 

 ceived theory of the propagation of sonorous undulations by an elastic 

 medium, advances the hypothesis that each particle of an elastic body, 

 after receiving an impulse in a particular direction, and communi- 

 cating that impulse to the adjoining particle, instead of being thereby 

 brought to a state of rest, is carried back by its elasticity with a velo- 

 citv which continues its motion beyond the point from which it origi- 

 nally set out, and is thrown into continual vibration, in a manner 

 analogous to the motion of a pendulum. He endeavours, on the prin- 

 ciple of a continual transfer of the state of each particle to the adja- 

 cent particles, to explain the phenomena of continued sound arising 

 from a prolonged succession of vibrations. 



" A Theory of the Tides, including a Theory of the Formation and 

 Propagation of Waves." By the same. 



The author applies the principle announced in his paper on the 

 Theory of Sound, namely, that of a continual transfer of state between 

 the adjacent atoms of a medium, to the case of oscillating columns of 

 fluid, constituting waves and tides. 



" On the influence of the Respiratory Organs in regulating the 

 Quantity of Blood within the Heart." By James Wardrop, Esq. 

 Communicated by the Hon. Captain De Roos, R.N., F.R.S. 



The author observes that the act of inspiration tends not only to 

 favour the passage of the blood into the venae cavse, but also to detain 

 it in the pulmonary vessels, — in consequence of the expansion of the 

 lungs allowing of its more ready ingress into the pulmonary arteries, 

 and impeding its exit by the veins — and thus retards its return to the 

 heart. On the other hand, the collapse both of the lungs and of the 

 parietes of the chest, during expiration, assists the transmission of 

 arterial blood from the lungs into the left cavities of the heart, and 



