TEANSACTIONS OF SECTION D. 801 



this end I used a simple bygrotneter, consisting of a shallow glass capsule, in the 

 flat bottom of which some calcium chloride solution had been evaporated to dryness. 

 The amount of water vapour discharged was ascertained by weighing the capsule 

 before and after it had been left inverted for a given period over the skin or other 

 surface of evaporation ; the corresponding quantity of heat emitted was taken as 

 equal to the weight of water x by the latent heat of evaporation. By preliminary 

 trials it was found that the water discharge varied from 2 to 20 mgrms. per 

 20 cm.- per 10 min. at various parts of the skin under ordinary varying conditions, 

 and that a capsule inverted over a wet surface can absorb between 80 and 90 

 mgrms. per 20 cm.- per 10 min.^ It was also found by trial on a wet cooling 

 sphere that the amoimt of heat ascertained by means of the internal thermometer 

 to be lost was approximately found by calculations fi'om the data furnished by the 

 external thermometer and the hygrometer conjointly. Thus, e.ff., against a loss 

 of 400 cals. per min. indicated by the internal thermometer there were 

 found 150 cals. by the surface thermometer (the T.D. being 12°, and taking out 

 from the calorimetric values tabulated above the corresponding number) plus 240 

 to 270 cals. by the evaporation of 400 to 450 milligrammes of water. 



Assuming that the graduation is not grossly inaccurate, and that the argument 

 upon which it rests is not grossly incorrect, the following numbers represent the 

 state of heat-emission from a human forearm, with a superficial area of 500 cm.-, 

 («) during rest after rest, (b) during rest after previous moderate exertion. The 

 air temperature during experiment was 20°. 



After Eest After Exertion 



T.D. 12° 14° 



I.e. heat-emission in cals. per min. . . 75 90 

 Water- emission in grammes per 20 cm." 



per 10 min 0004 0-030 



I.e. heat-emission in cals. per min. . . 6 45 



Total heat-emission in cals. per. min. . 81 135 



In carrying out investigations of this character, it is of great advantage to 

 employ the graphic method. Amount and rhythm of muscular exercise are 

 recorded by a dynamograph, as described in my ' Introduction to Human Phy- 

 siology'; surface-temperature by an air-thermograph, the essential part of which 

 is a thin metal box strapped to the limb, and connected with a piston-recorder in 

 contact with a slowly revolving cylinder, as will be described in a future com- 

 munication : the area of the thermographic curve thus recorded represents a calori- 

 metric value, and its ordinate a rate of heat-emission. 



The method is easily carried out ; the surface thermometer (or thermograph) 

 and the calcium chloride hygrometer are well adapted to the clinical investigation 

 of the heat and water emission of the skin under various pathological conditions. 



5. On a Method of Recording the Heart Sounds. 

 By Professor W. Einthoven. 



6. On Nerve Stimulation. By F. Gotch, F.B.S. 



7. On the Digestive Ferments of a large Protozoan. 

 By Marcus Hartog and Augustus B. Dixon. 



The authors have experimented with Pelomyxa palustris, of which the largest 

 individuals attain a diameter up to 2 or even 3 millimetres {^-^ inch). 



This organism, which is a gigantic multi-nucleate amoeba, is found in abundance 

 in the mud at the bottom of a small concrete tank at Queen's College, Cork. After 



■ Details will be given in a further communication dealing with cutaneous secretion. 

 1803. 3 r 



