12 THE POPULAR SCIENCE MONTHLY. 



based upon the different position of the communication between them 

 and the alimentary canal.* 



But another and perhaps more weighty objection has been urged 

 by Prof. Huxley. He says: "But such air- sacs are air-bladders 

 and not lungs, because they receive their blood from the adjacent 

 arteries of the body, and not direct from the heart, while their 

 efferent vessels are connected only with the veins of the general cir- 

 culation." 



According to this view, therefore, the Dipnoans {JProto2:itervs and 

 Lepidosireyi) have lungs, because the blood goes to the air-sacs by a 

 pulmonary artery, and returns by a pulmonary vein into a left auricle ; 

 while the cellular and vascular air-bladders of Amia and Leindostexis 

 are not lungs, because such an arrangement does not exist. 



Yet Prof Huxley applies the name placenta to the vascular inter- 

 digitations by which the young of some sharks are connected with the 

 mother, although they are developed from the yolk and not, as in 

 mammals, from the chorion. It would be interesting to know whether 

 the nerves of the air-bladder are the same as those of the lungs. 



The best test of the naturalness of the definition would be fur- 

 nished by the discovery of some form having the pulmonaiy vessels 

 connected with an air-bladder lying upon the dorsal side of the ali- 

 mentary canal. Meantime, since all are agreed upon the facts, the 

 question concerns interpretations and definitions. 



Whether or not the air-bladder of the gar-pike is entitled to the 

 name of lung, we may admit that it corresponds with a lung in its 

 essential connection with the alimentary canal, and apparently in its 

 function as an organ for aiding the oxygenation of the blood. 



-- 



MESMEEISM, ODYLISM, TABLE-TUENING, A^^D 



SPIRITUALISM.* 



By WILLIAM B. CAEFENTER, C. B., M. D., LL. D., F. E. S. 



I. 



THE aphorism that "history repeats itself" is in no case more true 

 than in regard to the subject on which I am now to address you. 

 For there has been a continuity from the very earliest times of a be- 

 lief, more or less general, in the existence of " occult " agencies, capable 

 of manifesting themselves in the production of mysterious phenomena, 



' In fact, considering the resemblance of the brains and enameled scales of Lfpidosteus 

 and Pohiptcrns, and the differences of their air-bladders and ducts, one is inclined to re- 

 gard the latter as of slight taxonomic importance. 



' This discussion, in which the subjects are considered historically and scientifically, 

 is an expansion of the lectures delivered at the London Institution. 



