1869.] Zoologtj. 569 



at about that hour and give up heat to the bed-clothes. Another 

 explanation he offers has a practical importance for every reader. 

 On a cold day the effect of sitting with one side of the body in the 

 direct rays of a fire is to cause the other side to feel much colder 

 than if there were no fire at all, because the fire lowers the tension 

 all over the body, and supplies heat to the full cutaneous vessels of 

 one side, while the other side being equally supphed with blood in 

 the skin, does not receive heat, but has to distribute it rapidly to 

 the cold clothes, &c. It should be mentioned that Mr. Garrod 

 takes the temperature beneath the tongue, and that the varia- 

 tions recorded are all between 97° and 100° Fahi'. — the variation 

 of a tenth of a degree being readily recognized. Some interest- 

 ing results of a similar nature might be obtained as to the 

 cause of still smaller fluctuations by means of the thermo-electric 

 scale. 



Tlie Cause of the Rouleaux of Blood Corpuscles. — Dr. Norris, 

 of Birmingham, has recently repeated to the Koyal Society the 

 explanation of the phenomenon of the aggregation of the blood 

 coi-puscles which he put out in a former paper in 1862, and has 

 exhibited his very ingenious and conclusive experiments. Dr. 

 Norris constructed discs of cork of the shape of blood corpuscles, 

 and found that when thrown into water they aggregated in the 

 same rouleaux as do blood corpuscles. But he found that this 

 result could not be maintained if the discs were perfectly sub- 

 merged : hence there was a considerable difference between the 

 case of the discs and of the corpuscles, which, of course, are 

 submerged. At length Dr. Norris found that if he wetted the 

 discs of cork or gelatine with which he experimented, and then 

 placed them in a hquid which would not mix with the water, that 

 the rouleaux were formed quite satisfactorily, even when the discs 

 were submerged. The formation of rouleaux then depends on 

 cohesive attraction — but on the cohesive attraction of two interacting 

 bodies — in all Dr. Norris's experiments, and in the blood there are 

 two dissimilar or antagonistic liquids; and upon the presence of 

 these two the phenomena depend. The air acts the part of one of 

 these in the case oi floating discs. All that is required in the case 

 of the corpuscles is a difference of this kind, between their hquid 

 contents, as Dr. Norris prefers to say, or their viscous substance, 

 as others may term it, and the plasma in which they are submerged. 

 The difference need not be so great by any means as the difference 

 between the liquids used in Dr. Norris's experiments (water and 

 parafiin), since the corpuscles are so excessively minute. 



The Movement of the CJiest in Besjiiration. — Dr. Burden 

 Saunderson has constructed an ingenious instrimient for measur- 

 ing the frequency and intensity of the respiratory pulse, as it may 

 be termed. Other physiologists have tried in various ways to con- 



