Scientific Intelligence. Physiology. 399 



of these regions is subdivided into zoological provinces which 

 are characterized by the existence of peculiar species. M. 

 Milne-Edwards terminates his communication by announcing 

 that he hopes speedily to finish the work he has undertaken up- 

 on this subject ; and that he is at the same time occupied with 

 analogous researches relating to the geographic distribution of 

 polypi. His observations on this latter subject lead him not less 

 to believe that there is also a very general misconception regard- 

 ing these animals, in admitting that identical species are equally 

 spread in the waters of the two hemispheres ; and his results, 

 though far from complete, demonstrate a tendency to an ar- 

 rangement altogether analogous to what is exhibited by the 

 Crustacea. 



PHYSIOLOGY. 



17. Experiments upon the Mechanism of the Motion or Beat 

 of Arteries ', by M. Flour ens. The question concerning the 

 movement of the arteries naturally divides itself into two in- 

 quiries, the former of which relates to the cause which pro- 

 duces this movement, and the latter to the mode in which 

 it operates. M. Flourens deems it best to canvass these ques- 

 tions separately, and commences with the one which refers to 

 the cause of the movement. As is generally known, the cause 

 which Galen assigned was " a pulse-giving power," which was 

 derived from the heart, and possessed by the coats of the ar- 

 teries ; but the author demonstrates, that the experiment upon 

 which Galen grounded this hypothesis is incorrect, and that 

 consequently his pretended pulse-giving power is only an empty 

 name. He then shows, by means of experiments he has per- 

 formed upon dogs and rabbits, that the true cause, a physi- 

 cal one, the immediate and direct cause of the movement 

 of the arteries is the impelling power of the blood, forced for- 

 ward by the contractions of the ventricles of the heart, a power 

 which had long ago been recognised and demonstrated by Har- 

 vey. As to the question regarding the mode in which the ar- 

 teries move, the author remarks, that it is by no means so simple 

 as that which relates to the physical cause of the motion. He 

 observes, " This important question, taken as a whole, has ap- 

 peared to me to be nothing more than the experimental deter- 



