Diseases of Domestic Animals, xxvii 



study lias rcnderetl the most essential services. The deer, 

 in the park of king Charles the first, with which he gene- 

 rously furnished Dr. Harvey, served to make some progress 

 in the discovery of the process of the evolution of the foetus^ 

 a suhject that has since heen greatly elucidated by De Graaf, 

 Spalanzani, Br. naighton,^? and Mr. Cruikshank.^o gy 

 experiments on other animals. Dr. Harvey also ascertained, 

 beyond contradiction, the circulation of the blood through 

 the body, and its rotatory motion by the heart arteries and 

 veins, so as to make many complete circuits round the body 

 in twenty hours.^^ 



4. It is to comparative anatomy we owe the discovery of 

 the lymphatic system, and the certainty of the use it was in- 

 tended to perform in the human body. The office of this ad- 

 mirable and curious system of vessels, is to absorb and con- 

 vey back to the blood, all the decayed parts of the human 

 body, (even bone itself,) and all those thin, pellucid iluids, 

 that wander from the course of the circulation, that they 

 may undergo new preparations, or be thrown entirely out of 

 the body : and in the intestines, they perform the important 

 office of conveying the nutritious and watery part of the 

 food into the system. Hence they arise from every organ 

 of the body. An opinion may be formed of the active pow- 

 er possessed by those apparently tender, and minute vessels, 

 from considering the rapidity witli which they transmit their 

 contents : this has been satisfactorily ascertained by Mr. 

 Cruikshank, to be at the rate of twenty feet in length, in one 

 minute. His experiments were made upon dogs, and the 

 well known facts of a peculiar smell in the urine, being 

 perceived in less than one hour after eating asparagus and 

 certain species of cabbage; and the increase of urine in the 

 same space of time, after drinking certain mineral waters, 

 lead us to suppose that the activity of the lactcals in man, 

 is equally great.^^ 



5. It is to this study we owe the discoveries of tlie cele- 

 brated Italian professor Spalanzani, I)r. -Stevens, John Ilun- 



voi,. ;tt. d 



