190 Proceedings of the Royal Society of Edinburgh. 



are successively developed from the semi-fluid matter of the ovum ; 

 and the particles of that matter must therefore have been much and 

 variously moved before the heart acts, or any contractile vessels have 

 been formed; and farther, that the human ovum itself, during the 

 time when it is surrounded on all sides by the shaggy chorion, must 

 draw its nourishment from the semi-fluid matter contained in the 

 uterus, through the filaments of the chorion, without the aid of any 

 contracting vessels in these filaments. These points appear esta- 

 blished by the observations of Prevost and Dumas, Breschet, Vel- 

 paeu, Raspail, and others. 



IV. The author considers the existence of attractions and repul- 

 sions, peculiar to the living state, among certain of the particles of 

 the blood of animals, to be established by due consideration of the fol- 

 lowing facts : 



1. By the phenomena of the coagulation of healthy blood, and the 

 utter absence of any contemporaneous mechanical or chemical change, 

 adequate to explain the change of aggregation of the particles of the 

 fibrin, on which that process depends. 



2. By the great retardation of that process, when blood (although 

 its circulation is arrested) is confined within a healthy living texture. 



3. By the great acceleration of that process, when the living tex- 

 ture, in which blood is contained, is severely injured. 



4. By the total suspension of that process, when death is produced 

 by a sudden and violent cause, especially by a cause which at the 

 same time destroys the power of contraction after death in muscular 

 fibres. 



5. By the diflTerent modifications of that process, which are ob- 

 served in inflammation. 



6. By the phenomena which are observed in those portions of blood, 

 which are extravasated in inflamed parts. 



In proof of these points, the author refers partly to personal obser- 

 vation, and partly to the works of Hunter, Hewson, Thackrah, Scu- 

 damore, Prater, Schrseder van der Kolk, Velpeau, Gendrin, Royer- 

 Collard, and Kaltenbrunner. 



V. The last set of observations, adduced in support of the general 

 principle, are those which, in reference to more complex questions in 

 physiology, are the most important, viz. those which indicate that 

 the blood circulating in the capillary vessels of living animals, and 

 examined by the microscope, exhibit a variety of movements, and 

 changes of "movement, which no visible or conceivable vital con- 

 tractions of the heart and arteries are adequate to explain. 



Most of these facts, as to the capillary circulation, were accurately 

 described, and the conclusion, which appears inevitable from them, 

 as to the existence, in the living state, of a peculiar cause of move- 

 ment inherent in the blood itself, or at least independent of any im- 

 pulse from contracting solids, was stated and carefully limited by 

 Haller. In regard to the rest, the author refers, not only to personal 

 observations, but chiefly to the authority of Dollinger, Wedemeyer, and 

 Kaltenbrunner in Germany, and of Quillot and Leuret in France. 



The analogies which may be traced, between the principle whicli 

 seems thus established, and other ascertained laws both of living 

 beings and of inorganic matter ; and the applications which may be 

 made of it, to the explanation of the more complex phenomena of the 



