ABSTRACT In 1935 Barcroft, Flexner, Herkel, McCarthy & McClurkin, working on rabbits, showed that the oxygen saturation of the blood leaving the uterus dropped from an average value of about 70 % at the 18th day of gestation to about 30 % saturation on the 30th day. During the period in question the foetuses are in active growth, whilst growth of the placenta is only trifling. On the 18th day the combined weight of the foetuses is approximately the same as that of the foetal portions of the placentas to which they are attached; on the 30th day the foetuses weigh about fifteen times as much as the placentas.

Journal of Comparative NeurologyVolume 77, Issue 2 p. 431-454 Article Observations on the functional development of the foetal brain Joseph Barcroft, Joseph Barcroft The Physiological and Anatomical Laboratories, Cambridge, England The Zoological Laboratory, University of MissouriSearch for more papers by this authorDonald H. Barron, Donald H. Barron The Physiological and Anatomical Laboratories, Cambridge, England The Zoological Laboratory, University of MissouriSearch for more papers by this author Joseph Barcroft, Joseph Barcroft The Physiological and Anatomical Laboratories, Cambridge, England The Zoological Laboratory, University of MissouriSearch for more papers by this authorDonald H. Barron, Donald H. Barron The Physiological and Anatomical Laboratories, Cambridge, England The Zoological Laboratory, University of MissouriSearch for more papers by this author First published: October 1942 https://doi.org/10.1002/cne.900770207Citations: 18AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume77, Issue2October 1942Pages 431-454 RelatedInformation

Pediatric AnesthesiaVolume 6, Issue 2 p. 142-142 The onset of respiration at birth SIR JOSEPH BARCROFT MA, Camb, FRS, SIR JOSEPH BARCROFT MA, Camb, FRSSearch for more papers by this author SIR JOSEPH BARCROFT MA, Camb, FRS, SIR JOSEPH BARCROFT MA, Camb, FRSSearch for more papers by this author First published: March 1996 https://doi.org/10.1111/j.1460-9592.1996.tb00377.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume6, Issue2March 1996Pages 142-142 RelatedInformation

Journal of Comparative NeurologyVolume 70, Issue 3 p. 477-502 Article The development of behavior in foetal sheep Joseph Barcroft, Joseph Barcroft Schools of Anatomy and Physiology, Cambridge University, EnglandSearch for more papers by this authorDonald H. Barron, Donald H. Barron Schools of Anatomy and Physiology, Cambridge University, EnglandSearch for more papers by this author Joseph Barcroft, Joseph Barcroft Schools of Anatomy and Physiology, Cambridge University, EnglandSearch for more papers by this authorDonald H. Barron, Donald H. Barron Schools of Anatomy and Physiology, Cambridge University, EnglandSearch for more papers by this author First published: June 1939 https://doi.org/10.1002/cne.900700308Citations: 57AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume70, Issue3June 1939Pages 477-502 RelatedInformation

Sheep embryos first respond to mechanical and electrical stimuli applied to them between the 33rd and 35th day after insemination. At this time movements may be elicited by tapping on the unopened amniotic sac or by faradic currents applied to the spinal cord or to the face. The movements appear to be due to the localized contraction of the muscles in the neck, the fore or the hind limbs. The actual neural elements concerned in the production of the movements of the limbs are not definitely known, but it is clear that these movements themselves are not as yet a part of a total mass reaction. If the movements of the limbs in these embryos could be shown to involve at least a primary sensory neuron and a motor neuron, the observations would lend support to the general thesis that behavior has its genesis in individual reflexes which are later associated into reaction patterns. We have, therefore, sought to produce isolated movements of the type observed in the sheep embryos under conditions in which we were certain a primary afferent neuron was stimulated as the first element in a reflex arc. Mechanical stimuli such as stroking the forelimb with a glass rod or flipping it do not induce either flexion or extension movements in sheep fetuses until 44–47 days after insemination. Reflexes in the hind legs cannot be elicited in these ways until 3 or 4 days later. There remains in these cases the possibility that the stimuli were not adequate in younger embryos to produce reflexes in the limbs. Fortunately fetuses 42 days old and slightly younger are large enough to be manipulated and dissected. We have found it possible to dissect out and to section the median nerve and also the lateral popliteal.

ArticlesTHE SIGNIFICANCE OF HEMOGLOBIN IN SUBMAMMALIAN FORMS OF LIFEJoseph BarcroftJoseph BarcroftPublished Online:01 Oct 1925https://doi.org/10.1152/physrev.1925.5.4.596MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByThe physiological ecology of haemocyanin in some selected crabs. I. The characteristics of haemocyamn in a tropical population of the blue crab Callinectes sapidus RathbunJournal of Experimental Marine Biology and Ecology, Vol. 10, No. 3 More from this issue > Volume 5Issue 4October 1925Pages 596-617 https://doi.org/10.1152/physrev.1925.5.4.596History Published online 1 October 1925 Published in print 1 October 1925 Metrics

ArticlesTHE SIGNIFICANCE OF HEMOGLOBINJoseph BarcroftJoseph BarcroftPublished Online:01 Jul 1924https://doi.org/10.1152/physrev.1924.4.3.329MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByHibernation in reptiles—II. Changes in blood cell glucose, haemoglobin, red blood cell count, protein and non-protein nitrogenComparative Biochemistry and Physiology, Vol. 17, No. 1 More from this issue > Volume 4Issue 3July 1924Pages 329-351 https://doi.org/10.1152/physrev.1924.4.3.329History Published online 1 July 1924 Published in print 1 July 1924 Metrics

The object which we had in view when we undertook the present research was to ascertain whether the pigment commonly alluded to as hæmoglobin in the worms was identical with that known by the same name in the vertebrates. Even in the mammalia there is some evidence that all hæmoglobin is not the same, many of the older observers held this to be the case; but since the discovery that the dissociation curve of hæmoglobin depends largely upon the conditions under which it is studied very little work has been done on the subject. It is known, for instance, that the blood of different persons differs slightly in its affinity of oxygen, under identical conditions, but such differences may be ascribed, rightly or wrongly, to variations in the intra-corpuscular atmosphere. More convincing evidence was put forward by C. G. Douglas, J. S. Haldane and J. B. S. Haldane (1) who showed that the blood of the mouse differed markedly from that of the human being. Their observations showed, among other things, that the curve which represents the reaction COHb+ O 2 ⇌ CO+HbO 2 in the mouse differed from that in man. This curve is little affected by the intra-corpuscular conditions of reaction and saline constitution, etc. Nevertheless one possibility was not excluded, namely, that the corpuscles of different animals should have a selective permeability for different gases.

What is reported in the following pages is an example of work achieved in a relatively short time by the co-operation of a sufficient number of institutions and individuals. The venue of this research was in the Andes, and the work was carried out in the winter 1921-1922, yet its organisation only commenced definitely in the early summer of 1921, when a group of British and American physiologists secured the support of the various universities or other institutions to which they were attached. This support was given in the most ungrudging way. It included the liberation from immediate duty of the members of the party, often at considerable inconvenience to those who remained at home, the loan of apparatus, the contribution of substantial funds, and a great body of goodwill, which was perpetually translating itself into increased efficiency of the work actually accomplished. The following collaborated in one or more of the ways indicated above:— The Department of Physical Chemistry of Harvard University. The Proctor Fund of Harvard University. The Elizabeth Thompson Fund. The Rockefeller Institute of Medical Research, New York City. Columbia University.—From a fund, to which contributions were made by Dr. Walter B. James, Mr. Cleveland H. Dodge, and a contributor who wishes to withhold his name, but to whom thanks are none the less due. The Royal Society of London. The Research Grant to the Physiological Department of the University of Toronto. The Moray Fund, Edinburgh. The Carnegie Fund, Edinburgh. Sir Robert Hadfield, Bart., F. R. S. Sir Peter Mackie, Bart.