III. 



Researches upon the Origin, Mode of Development, and Nature of the Spermatic Par- 

 ticles among the Four Classes of Vertebrated Animals. 



By WALDO J. BURNETT, M. D. 



(Communicated July, 1S50.) 



In the minds of those who are interested in, or have pursued, physiological studies, 

 there appears to be a kind of predilection for that branch relating to the primitive con- 

 ditions of being. The existence of an animated being, and the modes of its contin- 

 uation, considered as physiological facts, are such mysteries, that the mind naturally 

 turns, for the removal of these obscurities, to the very conditions attending its primitive 

 eHmination. 



To watch the new being, as it arises from an amorphous mass, starting into life, 

 gathering constantly the material forms for the expression of its type, — to watch its 

 gradual growth until it shall burst forth a living, thinking being, — to do all this has, with- 

 out doubt, been the source of higher delight, and of a happiness more transcendently 

 pure, than that afforded by any other study in which the scientific mind has ever been 

 engaged. It has been, perhaps, for this reason, that, from the earliest days, and more 

 particularly since those of available artificial optics, men of nearly every civilized part 

 of the world have been devoted with an untiring patience to the most thorough. and 

 correct study of embryology ; a branch of knowledge which can boast of more details, 

 and yet which is more unfinished, than any other in physiology. 



All studies of this kind are attended with difficulties of no usual character. Nature, 

 if I may so say, appears to have taken care that the finest expressions of her wisdom and 

 skill should be located in the most recluse situations. The paraphernalia surrounding 



VOL. V. NEW SERIES. 5 



