16 PROCEEDINGS OF THE AMERICAN ACADEMY 



the same subject. He coincided with Dr. Burnett in his ob- 

 servation of facts, but wished the investigation extended to 

 inchide the region of the Wolffian bodies. He had satisfied 

 himself that these bodies originated in the capillary system of 

 the pellucid area of the embryo. There is a circulation ^with- 

 in the transparent area of the embryo long before any circu- 

 lation of blood takes place; — a circulation of a transparent 

 fluid containing no blood corpuscles, but consisting of a series 

 of cell nuclei in a transparent fluid. From the resolution of 

 a series of these nuclei the circulation originates, and it is 

 entirely confined to the region of the head, in which the heart 

 is formed. He believed that there were three layers of the 

 blastoderma as first represented by C. E. von Baer, and that 

 these layers are essentially distinct. 



As soon as the eighteenth hour after incubation, the basis 

 from which the Wolffian bodies grow may be detected ; he 

 believed that these facts had hitherto been entirely overlooked. 

 The terminations of the Wolffian bodies are combined into a 

 vesicle, from which vesicle the allantois is properly a bud. 



With reference to the physical deductions of Dr. Burnett, 

 he had one objection to make. Naturalists were too apt to 

 describe the functions of the organs of undeveloped animals 

 by phraseology derived from the functions of animals in a 

 more advanced condition. He believed this to be dangerous, 

 and, notwithstanding the analogy between the allantois and a 

 urinary bladder, as shown by Dr. Burnett, he could not coin- 

 cide in the inference. 



Dr. Burnett said that his views of the Wolffian bodies were 

 quite different from those of Mr. Agassiz, and that he intended 

 to present them, at an early meeting, to the Academy. 



Professor Peirce described an experiment upon the forms 

 assumed, and the motions which arose, in a globule of oil held 

 in suspension in an alcoholic solution. 



Professor Agassiz called attention to the analogy between 

 these forms and motions, and those which arise in the earliest 

 embryonic cells. 



