Theories and Experiments 201 



The blood of a lamb or a sheep was brought me still warm from 

 the slaughterhouse, where care had been taken to break the fibers to 

 prevent coagulation. This blood I placed in a glass vessel with a wide 

 opening, and put the vessel in a receiver; the air was immediately 

 pumped out very carefully; but the effect of this operation was not 

 so prompt or so apparent, especially at the beginning, as I should have 

 expected it to be in so spirituous a liquid; however, after a long delay, 

 we saw that the most subtle parts of the blood appeared through the 

 more viscous parts, and formed bubbles, some of which were as large 

 as big beans or nutmegs; sometimes the expansion was so strong, that 

 the blood boiled up out of the glass vessel, of which, however, it 

 hardly occupied a quarter at the beginning of the experiment. (P. 46.) 



Robert Boyle drew air in the same way from other organic 

 liquids and all the soft parts. And he explains with keen sagacity 

 the purpose of these experiments; he wished to find out 



What, joined to the failure of respiration, could contribute to the 

 death of animals in the vacuum of the pneumatic machine; as a 

 matter of fact, it appears that the bubbles which, when the ambient 

 air is removed, form in the blood, the other liquids, and the soft parts 

 of the body, can by their number and their expansion in some places 

 swell and in others contract the vessels which carry blood and nour- 

 ishment into the whole body, especially the smallest of these vessels, 

 can choke passages or change their shape, and finally stop or disturb 

 circulation in a thousand ways. Add to that the irritation caused in 

 the nerves and the membraneous parts by forcible distentions; an 

 irritation which produces convulsions and causes death more quickly 

 than simple lack of air would have done. This formation of bubbles 

 takes place even in the smallest parts of the body, for I have seen a 

 very apparent bubble moving from side to side in the aqueous humor 

 of the eye of a viper at the time when this animal seemed violently 

 distressed in the receiver from which the air had been exhausted. 

 (P. 47.) 



In Part XIV there is reported a very fine experiment, by which 

 Boyle shows that animals become accustomed to the effect of the 

 rarefaction of the air, and suffer less from it in successive experi- 

 ments. 



Part XV. Experiment which shows that air can preserve its 

 elasticity while ceasing to be suitable for respiration. 



Part XVI. On the use of air for causing the escape of exhalations 

 from the body. 



Part XVII. Ability of the slug and the leech to endure lack of 

 air. 



Part XVIII. Trial of the vacuum upon certain crawling insects. 



Part XIX. Winged insects enclosed in a vacuum. 



Part XX. On the need of air for motion shown by ants and mites. 



In another work, 7 the celebrated physicist again dwells upon the 

 experiment relating to the bubbles of air which escape from 



