236 THE BLOOD. 



Several of these gentlemen have described the appearance of 

 the blood very differently ; but Haller, Spallanzani and J. 

 Hunter agree that the figure of the red particles is globular.* 

 Hunter observes farther, that the red globules do not run into 

 each other as two globules of oil would do when divided by 

 water ; and he believes that they cannot unite. At the same 

 time they seem not to have the properties of a solid : for when 

 circulating in the vessels, the^ assume elliptical forms, adapting 

 themselves to the size of the vessels. They also excite no sen- 

 sation of solidity when touched. 



They appear to be more heavy than the other parts of the 

 crassamentum : for in healthy blood the lower part of the mass 

 contains more of the coloring matter than the upper part ; and 

 in the blood of persons who labor under acute local inflamma- 

 tion, they often subside completely from the upper part; and 

 thus occasion what is called by Mr. Hewson the inflammatory 

 crust, or size. 



It has been observed by Mr. Hewson, and also by Mr. Hun- 

 ter, that the globules do not retain their form in every fluid. 

 They are said to be dissolved very quickly in water, and then 

 they form a fine clear red. Several of the neutral salts, when 

 dissolved in water, prevent the solution of the globules. Mr. 

 Hunter informs us, that the vitriolic acid, when greatly diluted, 

 does not dissolve them, &c. The muriatic acid, when three 

 times as strong as vinegar destroys their color without dis- 

 solving them, although when more diluted, it does dissolve them. 



to be found in the Philosophical Transactions of London, for 1664, in the fasci- 

 culi which are numbered 102 and 106. A more full description is contained in 

 Boerhaave's Academical Lectures on the Theory of Physic. See the section on 

 the nature of the blood. 



The glasses of Father De la Torre were transmitted from Naples to the Roy- 

 al Society of London in 1765. They were accompanied by a letter from Sir F. 

 H. E. Stiles, to which are subjoined some observations by the Rev. Father 

 himself. The letter and the observations are published in the 55th volume of 

 the Transactions of that society. 



In the year 1798, Tiberius Cavallo published an Essay on the Medicinal Pro- 

 perties of Factitious Air, with an Appendix on the Nature of the Blood, in 

 which is contained a farther account of the glasses of De la Torre. 



* I believe that this is also the opinion of Fontana. In J. Hunter's work on 

 the blood there are some interesting observations on microscopical deceptions. 

 See the note commencing in page 39, Bradford's edition. 



