xxvi INTRODUCTION. 



Dr. Willis 1 describes the filaments of the crassamentum as 

 joined together or concreted into a parenchyma. He knew 

 that serum is coagulable by heat and by some acids, and that 

 it is the lightest part of the blood. 



Malpighi 2 washed away the colouring matter of the clot, and 

 obtained the whitish fibrous part ; he insisted that polypi of 

 the heart are composed of this fibrous matter, and not of co- 

 agulated serum as was then generally supposed. He examined 

 the polypi and the pale substance of the blood-clot with a 

 microscope, and found them both made up of a fibrous texture 

 or network, adding that the buffy coat, which he calls pellea 

 crusta, has probably the same structure. His discovery of the 

 blood corpuscles is well known. 



Lower 3 gave a tolerably accurate account of the glutinous 

 fluid to which the coagulation of the blood and some of its 

 morbid appearances are owing. He was acquainted with the 

 effect of heat in coagulating the serum of the blood, lymph, 

 and the fluid of the pericardium. 



The observations of Borelli 4 are still more precise. He 

 described the compound nature of the clot and of the serum ; 

 the clot as consisting of white fibres or reticulated membranes, 

 the serum as composed partly of matter coagulable by heat, and 

 partly of water impregnated with salts. He concluded, from 

 microscopical observations on the fibres and on the capillary 

 vessels, that what he describes as the white, glutinous, and 

 spontaneously coagulable matter of the blood, is liquid in the 

 living body. 



Robert Boyle 5 describes the blood as dividing itself into a 

 fluid or serous and a consistent and fibrous part. He knew 

 that serum is coagulated by spirit of wine, by sublimate, and 

 by heat. 



Dr. Samuel Collins 6 states that the blood is composed of " a 

 crystalline liquor and red crassament, which coagulates when 



1 Diatribse duae Med. Phil, de Febribus, cap. i, pp. 13, 14, 8vo, Lond. 1659. 



2 De Viscerum Structura, accedit Dissertatio de Polypo Cordis, p. 156, 4to, 

 Bononiae, 1666. 



3 Tractatus de Corde, pp. 129-30, and 136, 12mo, Lond. 1669. 



4 De Motu Anftnalium, prop, cxxxii, p. 264, Op. Posth. pars alt. 4to,Roma3, 1681. 

 8 Natural History of Humane Blood, pp. 67, 73, 93, 12mo, London, 1684. 



6 System of Anatomy, vol. i, p. 42; vol. ii, pp. 747, 756-7, fol. London, 1685. 



