Scientific Lectures. 147 



you animals as tliey are now constructed, in conformity ■witli tlie 

 maxim of one of tlie greatest pliilosopliers who has wi'itten in the 

 English language, that " it is necessary to know the things that are 

 present with us, to have anything like an acquaintance with the 

 things that are past. Without detaining you further, then, I will 

 endeavor to give you first, the construction of the reptile, then of the 

 bird, and finally to exhibit to you the intermediate form of which I 

 have a gigantic specimen here, which, through the kindness of the 

 commissioners of the Central park, I have been allowed to bring 

 before you, prematurely, because they were unwilling that the illus- 

 tration should be wanting, and which is, in fact, the first installment 

 of the works I have the pleasure of executing for that institution. 

 In the first place, I would remind you that it is absolutely essential 

 for every living creature to have the means of feeding, and depositing 

 that food in such a situation that it may bear the same reference to 

 the living body as the fuel bears to the locomotive engine. We have, 

 then, here that essential portion. [Mr. H. here commenced to draw 

 a reptile on the blackboard, describing the details as he proceeded.] 

 I have some hesitation in introducing so unpoetic a portion of mj 

 subject at the commencement ; but it is followed by the next organ, 

 which is one that the poets have thought proper to immortalize, 

 while they have said nothing of the existence of this stomach, thej 

 are all agreed that there should be a heart. I am reversing, of 

 course, the grandeur of the poetical idea, when I say, no stomach, no 

 heart. We often speak of a " hearty " meal, though I am afi-aid that 

 would not quite justify me in putting the heart subsidiary to the 

 stomach. As I have compared the sack receiving the food to the 

 furnace receiving the fuel, you will forgive me if I speak of the heart 

 as the force-pump that distributes the material to restore and revivify 

 and reconstruct every part of the creature's body, renewing its 

 strength day by day and hour by hour. These are two essential 

 functions. The third is that which can supply the necessary air to 

 that vital fluid, rendering it thereby capable of doing its work, con- 

 sisting of a series of tubes or pipes, large trunks and small branches, 

 distributed over chamber or cells of tissue, and called the lungs ; by 

 means of which, those blood vessels receive the action of the oxygen 

 of the air, so arranged as to occupy the least possible cubic space, and 

 yet covering the largest possible amount of surface, thereby showing 

 the intention and the perfection of the design of that function, as we 

 find it throughout the whole animal creation. The oxygen reaches 



