August 1 6, 1888] 



NATURE 



377 



find Boreili (1608-79), in the second portion of his great work 

 *' De Motu Animalium," giving expression to very clear notions 

 regarding respiration. Thus in the eighty-second proposition he 

 shows that the lungs are not the effective causes of respiration, 

 but are passively concerned in the movements ; and in the 

 eighty-third proposition he states that the efficient cause of in- 

 spiration is the muscular force by which the cavity of the chest 

 is increased and permits the lungs to be filled by the elastic 

 force of the air. Boreili was also the first, as shown in the 

 eighty-first proposition of his work, to make an estimate of the 

 quantity of air expelled by a single expiration. At the same 

 time he attributed calm expiration to the elastic resiliency of the 

 ribs, and he pointed out that the deepest expiration could not 

 entirely empty the lungs of air (Propositions 92, 93, and 94). 

 Whilst Boreili thus recognized the air as necessary to animal life, 

 he naturally failed in explaining why this was so, being unac- 

 quainted with the composition of the air and of the so-called 

 " fuligineous vapours" (carbonic acid, aqueous vapour, &c.) 

 which were supposed to exist in expired air. 



I find, in a work by Swammerdam (1637-80), dated 1667, 

 and entitled " Tractatus Physico-Anatomico Medicusde Respira- 

 tione usuque Pulmonum," at pp. 20, 21, a description of an 

 experiment in which he immersed in a vessel of water a dog 

 having a long tube inserted in the trachea, and he observed the 

 rise and fall of the level of the water during respiration. This 

 was practically the method followed by Boreili, but I am unable 

 to say which experiment was first performed. 



Here I may also refer to the curious experiments of Sanctorius, 

 Professor of Medicine in Padua, who flourished from 1561 to 

 1636, as being probably the first quantitative estimate of sub- 

 stances escaping from the body. Sanctorius constructed a balance 

 by which he weighed himself repeatedly, and observed what he 

 gained by food and what he lost by excretion. The results 

 appeared in his work " Ars de Statica Medicina," published in 

 1614, and he states the amount of matter separated by pulmonary 

 exhalation at about half a pound in twenty-four hours. It is not 

 easy to say precisely what these figures represent, and therefore 

 we find the amount, on the authority of Sanctorius, differently 

 stated by writers during the next century. His observations are 

 of interest, however, as being a distinct step in physiological 

 investigation. 



Among the contemporaries of Boyle, Pascal, Spinosa, Barrow, 

 Newton, and Leibnitz— all men of the first intellectual rank — 

 was Dr. Robert Hooke, one of the most versatile and able of 

 scientific thinkers. Hooke was born in 1635, and died in 1703. 

 One of the founders of the Royal Society, its early Proceedings 

 show that there was scarcely any department of science at the 

 time to which he did not make important contributions. In 

 particular, he showed a remarkable experiment, in October 1667, 

 to the Royal Society. This experiment, as detailed in Lowthorp's 

 " Abstract of the Philosophical Transaction-," vol. iii. p. 67, 

 showed that it was the fre h air, and not any alteration in the 

 capacity of the lungs, which caused the renewal of the heart's 

 beat. It has been said that a similar experiment was performed 

 by Vesalius, but with this difference, that, whilst Vesalius observed 

 the fact, he failed in giving a rational explanation. He supposed 

 that the movements of the lungs affected the movements of the 

 heart, but he did not see, as Hooke did, that the heart moved 

 because it was supplied with blood containing fresh air. Hooke's 

 experiment is one also of great practical importance as being the 

 basis of the modern practice of using artificial respiration in cases 

 of impending asphyxia. 



We thus see that the necessity of a continual supply of fresh 

 air was recognized as being essential to life. It was further sur- 

 mised that the air imparted something to the blOod, and received 

 something in return ; but no further advance was made in this 

 direction ur.til the researches of Mayow, a name now famous in 

 the early history of chemistry and of physiology. John Mayow 

 was born in 1645, an d died at the early age of thirty-four. His 

 principal work was published in Oxford in 1674. In it, by many 

 ingenious experiments, he showed that combustion diminishes 

 the volume of the air and alters its qualities ; that respiration 

 also affects the quality of the air ; that an animal will die if kept 

 in a confined space full of air — a fact to be explained, according 

 to Mayow, by saying that the animal had used the respirable 

 portion of the air, and that the residue was unfit for life ; and, 

 finally, he showed that an animal suffers if placed in an atmo- 

 sphere the qualities of which have been injured by combustion. 

 Further, he gave the name of " nitro-aerial spiritus" to the 

 "principle" in the air which, he said, had to do with life, 



muscular action, and combustion. Thus he no doubt came near 

 the discovery of oxygen, made by Priestley nearly a century later. 

 It would be difficult to estimate the enormous influence on 

 theories of combustion and of respiration exerted by the re- 

 searches of Hoyle, Hooke, and Mayow. They prepared the 

 way in physiological science for the next great step— namely, 

 the identification of the gaseous elements contained in respira- 

 tion. The dependence of progress in physiology on the state 

 of scientific opinion regarding chemical and physical questions 

 could not be better illustrated than in the history of physiologi- 

 cal ideas regarding respiration. Thus the researches of Boyle 

 with the air-pump did much to explain the mere mechanism of 

 breathing. Hooke made this even more apparent, and Mayow 

 gave greater precision to the idea that in respiration the blood 

 lost something and gained something. It is difficult to deter- 

 mine precisely, after the lapse of time, the contributions made 

 by each of these distinguished observers, who were contem- 

 poraries ; but I would venture to say that the germ of the ideas 

 that bore fruit in the minds of Hooke, and more especially of 

 Mayow, may be found in the writings of Robert Boyle. 



The researches of Mayow, indicating the existence in the air 

 of a "nitro-aerial spiritus " necessary to life, and the presence 

 in expired air of something deleterious to life, did not imme- 

 diately produce the fruits one would have expected. At first, 

 his writings attracted considerable attention ; they passed through 

 two or three editions, and were translated for Continental 

 readers ; but from the beginning of the eighteenth century, 

 nearly twenty years after Mayow's death, they passed almost 

 into oblivion. Thus Hales vaguely refers to him in only two 

 instances, and, as stated by Bostock, " in the discourse delivered 

 by Sir John Pringle before the Royal Society, upon the assign- 

 ment of Sir Godfrey Copley's medal to Dr. Priestley, which 

 commences with a sketch of the discoveries that had been made 

 in the science of aerology, previous to the period when this 

 philosopher entered upon his experiments, the name of Mayow 

 is not mentioned." 



Mayow's writings were first again brought into notice in this 

 country by Reinhold Forster, who gave a summary of Mayow's 

 views in an introduction to his translation of Scheele's essay on 

 " Air and Fire." 



As another example of how Mayow's observations were neg- 

 lected, it may be pointed out that Boerhaave (1668-1738), one 

 of the most learned men of his time, states that he cannot ex- 

 plain the change which the air experiences by respiration ; and 

 even Haller, in his great work " Elementa Physiologise Corporis 

 Hutnani," published in 1766, sums up his knowledge regarding 

 expired air by stating that it is combined with a quantity of 

 water and a noxious vapour, and has its elasticity diminished. 



The next step in the physiology of respiration was the dis- 

 covery, in 1754, of carbonic acid, by Joseph Black, then Professor 

 of Medicine and Chemistry in this University. About this time 

 there was much discussion in the medical world as to the use of 

 lime-water in cases of stone and gravel. It was supposed that 

 the lime-water dissolved calculi, and assisted in expelling them 

 from the body. A discussion arose as to the virtues of lime- 

 water produced from different substances. Two Professors in 

 the University of Edinburgh — Alston and Whytt — specially in- 

 vestigated the subject, and Whytt asserted that the lime-water 

 of oyster-shell lime had mere power as a solvent than the lime- 

 water of common stone lime. This led Black to examine the 

 question. " I therefore," says he, "conceived hopes that, by 

 trying a greater variety of the alkaline earths, some kinds might 

 be found still more different by their qualities from the common 

 kind, and perhaps yielding a lime-water still more powerful 

 than that of oyster-shell lime." 



This led Black to his celebrated investigation on magnesia. 

 He showed that in the case of magnesia alba (carbonate of 

 magnesia) the disappearance of the effervescence on treatment 

 with an acid after heating was accompanied by a loss of weight. 

 The substance thus given off he called "fixed air," or what we 

 now term carbonic acid. This led to an examination of the salts 

 of lime, and in 1757 he made two important physiological dis- 

 coveries, namely : (1) that the fixed air was injurious to animal 

 life ; and (2) that fixed air was produced by the action of 

 respiration. These important observations are thus described in 

 his own words : — " In the same year, however, in which my first 

 account of these experiments was published — namely, 1757 — I 

 had discovered that this particular kind of air, attracted by 

 alkaline substances, is deadly to all animals that breathe it by 

 the mouth and nostrils together ; but that if the nostrils were 



