110 



NORMAL HISTOLOGY. 



processes, become round, and swell up into larger spheres ; mean- 

 while, the protoplasm resolves itself into a number of sharply-cut 

 granules, which, owing to their suspension within a fluid of less 

 density than the blood-plasma, exhibit the active dancing or oscil- 

 latory movements which constitute the " Brownian motion," a 

 phenomenon entirely physical in nature. The nuclei of the colorless 

 cells after treatment with water appear as clear or slightly granular 

 areas among the vibrating particles. After a time the distention 

 of the corpuscle becomes too great, and rupture takes place, followed 

 ^A by the escape of the particles of disintegrated protoplasm. 



Acids. Upon the addition of weak acetic acid the red cells 

 become rapidly decolorized-, at the same time losing the discoidal 

 form and approacKIng~the spherical. The protoplasm of the color- 

 less corpuscles clears up entirely, the nuclei coming very con- 

 spicuously into view. Upon subsequent treatment of acid prepara- 

 tions with aniline, the nuclei of the white cells appear deeply stained, 

 while the red cells are outlined by faintly-colored rings. 



Tannic acid, when applied to the red corpuscles in weak (one- 

 half to one per cent.) solutions, produces a peculiar effect: the 

 coloring matter of the corpuscle is coagulated as it escapes from the 

 cel^and becomes conspicuous as a minute accumulation adhering to 

 one edge of the corpuscle. Where .strong solutions of tannic acid 

 are employed, the^haemioglobin is coagulaea within the corpuscle 

 before it has had an opportunity to escape, producing appearances 

 which have been mistaken for nuclei and other details of cell-structure. 

 The Blood- Platelets. If human blood be drawn directly into 

 a drop of osmic^ acid solution (one per cent.) or of a three-fourths 

 per cent, solution of sodium chloride, 

 covered at once, and examined with a high 

 power, numbers of small, colorless, circular 

 disks will be seen on careful observation ; 

 these are the blood-platelets of Bizzozero, 

 sometimes called the third corpuscular ele- 

 ments of the blood. They are very unstable, 

 prone to disintegration, and are variable in 

 size, possessing an average diameter of about 

 one-third of that of the red cells ; they 

 occur singly, but show a marked disposition 

 to run together in groups preparatory to 

 breaking up into the minute particles long 

 known as the granules of Max Schultze. 



Unless great precaution is taken to insure the immediate action of 

 the preserving fluids, the blood-platelets will not be seen in their 

 normal form. 



\ 



human red blood-cells and 

 blood-platelets (/) ; g , minute 

 fatty (?) particles, which occur 

 isolated or in masses ; B, fibrin 

 filaments, among which lie par- 

 tially disintegrated blood-plate- 

 lets. 



