Dissection of the Phoca cristata. 103 



The heart, like that of all the mammalia, was very large, 

 and by inflation and injection, we satisfied ourselves that 

 the foramen ovale was closed ; so that the opinion of Cuvier, 

 that the foramen ovale is not open, but that the size of the 

 vena portae answers the same purpose, by enabling the animal 

 to remain long under water without breathing, is confirmed by 

 our observations on this animal. 



Observations on the North American species of the genus 

 Gratiola. By Capt. John Le Conte of the U. S. 

 Army, F. L. S. &c. Read March 22, 1824. 



Is certainty unattainable in human pursuits, when they are 

 not connected with mathematical science ? This question, 

 which has been so frequently asked, must have presented itself 

 with peculiar force to the mind of every naturalist. He sees 

 every where around him systems adopted and laid aside ; 

 facts at one time admitted, and almost immediately afterward? 

 controverted ; what but a few years ago was considered as 

 fixed beyond the reach of doubt, now entirely overthrown ; 

 new names, new distributions are for ever appearing : while 

 nature, from whom all these things are pretended to be de- 

 rived, is unchangeable. Can what is so variable have pro- 

 ceeded from her ? or do we only flatter ourselves, when we 

 call the suggestions of our fancy, the arrangements of nature ? 

 Nature is constant, but our own prejudices, our vanity, 

 and our blind presumption mislead us. Few, however willing 

 they may be, see with their own eyes. The authority of 

 personal experience, weighs nothing against the whims of a 

 favourite author, and we willingly choose to fetter our reason, 

 and to entangle our faculties in the mazes of others' imagi-^ 

 nations. 



