88 



NATURE 



[May 25, 189c 



the heads of the departed to facilitate the exodus of any malignant 

 influence still lingering within, and to ensure them, by^the vener- 

 ated aperture, a satisfactory position in their new existence. 

 For similar reasons the bone amulet was buried with the deceased, 

 and sometimes it was even placed within his skull. Dr. 

 Munro considers it hard to say for what purpose such an in- 

 sertion should have been made, but, arguing from his data, the 

 practice does not appear to me difficult of explanation. He has 

 shown that disease was the work of a demon imprisoned in 

 the skull ; that this demon was expelled through the trepanned 

 hole ; and that its margins were thus sanctified for talismanic 

 purposes. The unclean spirit was gone out of the man, and 

 observation showed that, during the man's earthly existence, 

 he did not return ; but what guarantee was there that in the dim 

 unknown region to which the deceased was passing the assaults 

 of the evil one might not be renewed, that he might not return 

 to his house whence he came out, and, with or without other 

 spirits more wicked than himself, enter in and dwell in the swept 

 and garnished abode? Surely, with such a possibility before 

 them, it was the duty of pious mourners to offer all the protection 

 that religion could suggest, and to defend the citadel with that 

 potent amulet which recorded the previous discomforture of the 

 besieger. The post mortem trepanning may have been such a 

 pious endeavour to carry sacramental benefits beyond the grave, 

 as induced the early Christians to be baptised for the dead, and, 

 if there be truth in the deductions which have been made from 

 the evidence, they point not only to a belief in the supernatural 

 and in the existence of a future state, but also to that pathetic 

 struggle of human love to penetrate the kingdom of death, which 

 has persisted from the death of "Cain, the first male child, to 

 him that did but yesterday suspire." 



The possibility of reasonably making such deductions from a 

 few decayed bones is a remarkable proof of the progress of 

 anthropological science. Should any readers regard these de- 

 ductions as unwarranted, they must remember that their value 

 is dependent upon a series of facts which can here only be but 

 very imperfectly reproduced. For these evidences in full 

 sequence reference should be made to the paper by Dr. Munro, 

 which forms the subject of this notice, and which will amply 

 repay perusal. Fr.\nk Rede Fowke. 



ANIMAL HEAT AND PHYSIOLOGICAL 

 CALORIMETRY} 



'X'HE problem of animal heat is one of the oldest problems of 

 scientific speculation. Nevertheless it is only within 

 recent years that we have been able to speak of it in terms of 

 modern knowledge. 



Among the earliest contributors to such knowledge we may 

 cite John Mayow and Joseph Black. Mayow was the 

 first to suggest that atmospheric air is not a simple element and 

 that its "nitro-aeric particles," in combining with the blood 

 in the lungs, produce the animal heat, while Black demonstrated 

 that the air expired by the lungs contains " fixed air" or, as we 

 now call it, carbonic acid. 



Priestley discovered oxygen gas in 1 77 1, but Lavoisier 

 was the first to show that this constituent of the air is taken in 

 by the blood in the lungs, and that its combination with the 

 carbon, which is a regular constituent of all organic matter, 

 produces animal heat in the same way as in all combustions. 

 Lavoisier was the first, too, who measured the heat produced 

 by an animal, making use of the ice calorimeter, constructed 

 by himself and Laplace, while Crawford nearly at the 

 same time made investigations with an apparatus similar to our 

 water calorimeter. 



Neither form of apparatus is very suitable for this pur- 

 pose. Scharling, Vogel, and Him made use of an a'r 

 calorimeter. Within the last few years Prof. d'Arsonval of 

 Paris adopted the same principle, and I myself have'worked out 

 the theory of it, and constructed apparatus, with which I have 

 made a great number of experiments. 



The animal to be experimented upon in my apparatus is 

 placed in a chamber surrounded by double metallic walls. The 

 heat given out by the animal raises the temperature of the 

 air contained between the walls, until the radiation from the 

 outer surface causes a loss of heat equal to the amount gained 



1 Paper by Prof. Rosenthal of Eriangen. read before the Biological 

 Section at the Edinburgh meeting of the British Association for the Ad- 

 vancement of Science. 



NO. 1230, VOL. 48] 



by it from the animal. This state of things having been 

 established, the temperature of the air becomes constant, the 

 gain and loss of heat being equal. In this way the heat 

 given out can be calculated. ^ 



The chamber containing the animal is well ventilated by aspira- 

 tion. If we measure the volume of the air aspired and con- 

 duct a part of it through liquids absorbing carbonic acid, the 

 amount of this gas given out by the animal can be measured. 

 In another series of experiments the amount of oxygen absorbed 

 by the animal was also measured. The combination of apparatus 

 I made use of for this purpose is a variation of the method 

 invented by Regnault and Reiset. 



I shall not weary you with a long enumeration of all my experi- 

 ments. All I wish is to give a brief account of some of the 

 results, which X think are of interest from a general biological 

 point of view. 



In the first place, I may mention my experiments on fever. 

 The high temperature in cases of febrile disease — is it the result 

 of greater heat production? Are we to assume that certain 

 poisons taken into the body, or produced in it by microbes, 

 stimulate the nervous system, or directly influence the tissues in 

 such a way as to cause greater oxidation, and thus to produce 

 more hent ? 



That is the opinion of many medical men, but it is met with 

 the great difficulty that neither the expiration of carbonic acid 

 nor the excretion of oxidized nitrogenous matter is increased to 

 such a degree as to account fully for the rise of temperature. 

 Therefore Traube, the late clinician of Berlin, proposed the 

 theory that the rise of temperature in fever is caused, not by 

 greater heat production, but by greater retention of heat. 



On producing fever in animals by injection of various putrid 

 substances, I found that at the beginning of the fever, heat 

 production is not increased, that the loss of heat is diminished, 

 and that the difference between the normal loss and that ob- 

 served in the period of rising temperature is sufficient to cause 

 the febrile rise. When the temperature reaches its highest 

 point the amount of heat given out rises and comes to its 

 normal rate. Finally, when the fever begins to subside, during 

 the period of falling temperature, the loss of heat is greatly 

 increased. 



All this is in perfect accordance with Traube's theory. 

 Nevertheless, I cannot say that heat production is never aug- 

 mented in fever. I have not yet been able to make many 

 experiments on man. There are two great difficulties in 

 the way, and the greatest is the impossibility of making a 

 strict comparison between the heat production in fever and that 

 in the normal state, except :in cases of the regular inter- 

 mittent type. Malaria, once so frequent in several parts of Ger- 

 many, nowadays, thanks to hygienic improvements, is very seldom 

 met with. So I have been able to make only two experiments 

 on an individual afilicted with intermittent fever, some on in- 

 valids with abdominal typhus (typhoid fever), some on cases of 

 pneumonia, and others on cases of fever caused by the injection 

 of Koch's tuberculine during the short time when such injec- 

 tions were practised in the hospitals of Eriangen. In these 

 cases I found a small but real augmentation of heat production, 

 and therefore I am inclined to suppose that the question is not 

 yet solved. Perhaps there are two causes able to raise the 

 temperature in fever, one of them prevailing in some cases or 

 types of fever. 



Most of my studies were conducted with a view to 

 explain the connection between heat production and other 

 physiological functions, and the influence of external circum- 

 stances on it. Higher animals, mammals and birds, maintain 

 their own temperature nearly at the same degree, even when the 

 temperature of the surrounding air changes within large limits. 

 Is this regulation, as we call it, caused by adaptation of heat 

 production to the greater or smaller loss, or are there means to 

 keep the loss constant in spite of the changing difference between 

 the animal and surrounding objects? 



On measuring the heat production of the same animal in cold 

 and warm air, I found that it is smallest in air of medium tem- 

 perature, i.e. about 15' C, becoming greater in lower and in 

 higher temperatures. Thus an animal produces and loses 

 nearly the same amount of heat in air at 5° as in air at 25°. 

 In this c.ise regulation of the animal temperature can be eflfected 

 only by changes of the co-efficient of emission of heat from the 

 skin, caused by changes of circulation. But for longer periods 



^ For a fuller account see my Y>^^Ts\a'.Archiv fur Pliysieio^ie, iSSg, and ia- 

 Sitziwgsber. d. K. pTCuss. Akad. d. Wissensch. i888-i3>)2. 



