544 TRANSACTIONS Of SECTION I. 



Now we easily understand that a much larger quantity of C0 2 , up to two per 

 cent., produced no inconvenience in At water's respiration chamber, where the 

 moisture was continually condensed by the heat absorbers, which keep the 

 temperature of the chamber on a constant level. In the result we cannot 

 agree totally with Dr. Hill's conclusion that movement of the inside air by 

 fans, which cools down the temperature of the skin, may replace normal 

 ventilation with fresh air. Such action of fans will certainly elevate the 

 efficiency of the included working men to normal height for some hours. But 

 if we wish to keep the room in a sanitary state, we must either increase the 

 fresh-air ventilation to the standard prescribed by Pettenkofer, or we must 

 condense and eliminate the overplus of moisture by cold surfaces, as is done in 

 the apparatus of Atwater. 



The following Papers were then read : — 



1. Heat Production and Body Temperature during Rest and Work. 

 By Professor J. S. Macdonald and Dr. J. E. Chapman. 



2. Certain Physical Questions regarding Blood-vessels and Blood-cells. 

 By John Tait, M.D., D.Sc. 



Lister showed the cause of blood coagulation to be contact of the blood with 

 (chemically) inert materials, such as glass, wood, hair, &c. The physical pro- 

 perty in virtue of which these substances excite coagulation became for the first 

 time clear when Freund discovered that contact of blood with greasy substances, 

 such as vaseline or oil, does not produce clotting. In order that clotting may 

 occur blood must come in contact with a material to which it can adhere. As 

 Freund himself suggested, blood remains fluid in the blood-vessels because the 

 lining endothelium is physically so constructed that adhesion between it and 

 the blood is negligible. 



When the aorta of a recently killed rabbit is slit open longitudinally and 

 23inned out flat, one can readily see, by pouring defibrinated blood of the same 

 animal over the inner surface, that to certain patches at least the blood does 

 not adhere. Mr. J. A. Hewitt and the present author have found that a scraping 

 of vascular endothelium removed on the blade of a knife becomes jet-black when 

 exposed to the vapour of osmic acid. They have also estimated the amount of 

 ether-soluble material in the dried aortic endothelium of the ox, and discovered 

 the presence of as much lipoid as in the dried stromata of red blood corpuscles. 

 There is thus as much justification for considering vascular endothelium a lipoid 

 lining as there is for considering the envelope of red blood corpuscles of lipoid 

 nature. 



This fact may be of importance in relation to problems in haemodynamies, to 

 problems of absorption through capillaries, to the combined haemorrhagic and 

 hemolytic action of certain snake-venoms and to the frequent association of 

 certain haemorrhagic and lymphatic diseases with haemoglobinuria, i.e., with 

 haemolysis. (From the fact that blood does not necessarily clot when brought 

 in contact with the serous membranes of the body, it is probable that serous 

 endothelium, and possibly the endothelium of the lymph-vessels, is likewise 

 rich in lipoid.) 



Certain cells of the blood, e.g., the spindle-cell of Sauropsida and Ichthyop- 

 sida, and the amoebocytes 1 of invertebrates, adhere firmly to substances like 



1 The alleged ' amoeboid ' movement of colourless invertebrate blood-cor- 

 puscles, which have been placed on a glass slide, is merely a spreading out of 

 the corpuscle, like the spreading of a rain-drop on a stone. The so-called pseudo- 

 podia, once extruded, are never withdrawn again. The movement is a progres- 

 sive expansion due to the adhesion of the glass, and in thus being irreversible ia 

 no true amoeboid movement. 



