306 Proceedings of PhUosop/dctit iiocieties. [April, 



Article XL 

 Proceedings of Pliilosophical Sociclies. ' ' 



ROYAL SOCIETY. -, i 



March 3. — The reading of Dr. Williams's paper on the 

 Maternal-foetal Circulation, was resumed and concluded. This 

 essay oave an account of the different speculations entertained 

 on the nature of the naedium circulating between the uterine and 

 \imbilical vessels, and considered the evidence brought forward 

 in their support to be unsatisfactory. It then stated, that it had 

 occurred to the author that it might be practicable to arrive at 

 more satisfactory proofs in favour of one or the other of these 

 speculations by observing the phaenomena which would present 

 themselves in the foetal vessels on injecting oil into the maternal 

 vessels, while their irritability was yet active. Experiments 

 Avere consequently instituted. From their result. Dr. W. is dis- 

 posed to conclude, thatthe maternal and foetalsystems in the canine 

 species, are parts only of a common uninterrupted sanguife- 

 rous system. From analogy, Dr. W. also infers the communi- 

 cation' between parent and foetus to be similar in all viviparous 

 animals ; and remarks, that if his conclusion and inference can 

 be admitted, that we shall have reason to doubt the validity of the 

 doctrine of the maternal-fcetal circulation as taught by Dr. 

 Harvey, together with its modern superstructure. For that if 

 his, Dr. W.'s, experiments and deductions be correct, we can no 

 longer subscribe to the hypotheses of there being two independ- 

 ent sanguiferous circulations in the impregnated state, and to 

 that of the placenta being an organ of respiration or aeration. 



Dr. J. R.Johnson, FRS. communicated Some further Obser- 

 vations on the Genus Planaria ; in which he stated that Mr. 

 Dalyell, of Edinburgh, in a work on the Planariaj, having as- 

 serted that an individual of P. cornuta accidentally wounded 

 near the head produced a new head from the incision, he con- 

 ceived that the verification of so curious a fact would be inter- 

 esting to the Royal Society, and accordingly took one hundred 

 of the animals, and made an incision in the side of each; but 

 one of them, however, produced the new head: in the greater 

 number, the w^ound healed, and in some preternatural excres- 

 cences only were produced. Dr. J. proceeded to detail some 

 further remarks on the reproductive faculties of the Planariaj, 

 and to describe P. nigra, of which a drawing was annexed. It 

 has the abdominal proboscis like the others. 



March 10. — i. H. Green, Esq. was admitted a Fellow of the 

 Society ; and Mr. Herschel communicated a paper entitled 

 Improvements on Leslie's Photometer; by W, Ritchie, AM, 

 Rector of the Academy of Tain. 



