90 



away all the winter months of the year, nature 

 has, as in the case of insects while undergoing 

 their metamorphoses, provided against any in- 

 convenience from this cause, by causing them to 

 get very fat on the approach of winter, so that 

 they subsist, during the period of their hiberna- 

 tion, on their own fat, which is gradually absorbed 

 into their blood. 



The next subject of consideration is the circu- 

 lating organs, or those by which the blood, thus 

 at intervals renewed, is carried to every part of 

 the body. In the simplest orders of animals 

 these organs of course do not exist ; since, hav- 

 ing no proper digestive organs, but assimilat- 

 ing the crude alimentary matters received by 

 imbibition, equally in every part of the body, 

 there can be no occasion for any system of vessels 

 to carry these matters from one part to another. 

 In the greater number of zoophytes, accordingly, 

 proper blood-vessels are wanting, because they 

 are destitute of a stomach and intestines ; but as 

 soon as these are met with, in the ascending 

 scale of creation, they are found to be accompa- 

 nied by proper vessels, for conveying the matters 

 thus prepared throughout the rest of the system. 

 We may thus, if we please, regard the circulating 

 organs as a kind of appendage to those appropri- 

 ated to digestion ; and, indeed, the first rudiment 

 of a vascular system, in animals, presents rather 

 the appearance of elongated intestines than of 

 proper blood-vessels. Such is the case in the 



