THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Washington, D. C, Octobek, 1886. 



Vol. YII. 



No. 10. 



On the So-called New Element of 

 the Blood and its Relation to 

 Coagulation. 



BY GEO. T. KEMP. PH. D., UNIVER- 

 SITY OF PA.* 



Hayem, in 187S, called attention 

 to bodies in the blood vsdiich were 

 not previously noticed. He called 

 them hcematoblasts^ and endeav- 

 ored to 231'ove that they were early 

 stages in the development of I'ed cor- 

 puscles. In 18S1 Bizzozero claimed 

 independent discovery of the same 

 elements, and affirmed that they 

 were connected with the coagula- 

 tion. Much conflicting research 

 followed, and finally Dr. Kemp, of 

 Johns Hopkins University, present- 

 ed a paper, of which this is an 

 abridgment. 



The element is called by the term 

 plaque^ used by the French observ- 

 ers. 



If a drop of i per cent, osmic acid 

 be placed on the finger, and the fin- 

 ger pricked with a needle through 

 the drop, the elements of the blood 

 will all be hardened and preserved 

 in their natural appearance. 



If a thin film of this blood be ex- 

 amined with a good lens magnify- 

 ing 600 to 800 diameters, the plaques 

 may be seen floating in the plasma 

 among the red corpuscles and leu- 

 cocytes. 



They are pale, homogeneous, vari- 

 able in size, about one-third to one- 

 fourth the diameter of a red coi-puscle. 

 Seen on surface, they are circular or 

 elliptical, and seem at first sight flat, 



♦Abridged for this Journal from the original article 

 in the Studies from the Biological Laboratory of Johns 

 Hopkins University. 



but are veiy slightly biconcave, as 

 shown ^vhen seen edgewise. 



The foriTi of the plaque when thus 

 studied never vmdergoes change. This 

 is not the case in blood drawn and al- 

 lovk^ed to clot. To study this the fol- 

 lowing method is adopted : — The fin- 

 ger is pricked and a good-sized drop of 

 blood squeezed out and taken imme- 

 diately upon a cover-slip. Then, as 

 quickly as possible, most of it is 

 washed oft' by a jet of .75 per cent. 

 Na CI solution from a wash -bottle. 

 The slip is now examined under the 

 microscope. The plaques have the 

 property of sticking to the slip while 

 the other elements are washed away 

 by the jet, so that, on examination, 

 the whole field is found filled with 

 plaques mostly grouped in masses of 

 3-12 or more. 



They are no longer pale and homo- 

 geneous with symmetrical outline, but 

 appear glistening and granular, and 

 their contour has become jagged. 

 These changes are more marked the 

 longer the time which has elapsed 

 before the preparation is observed, 

 and they may be seen to take place 

 step by step while a prepai-ation is 

 being watched. This change pro- 

 gresses vmtil only a granular mass 

 remains, the individual plaques be- 

 ing no longer distinguishable. Pari 

 passu with these changes processes 

 may be seen to run out from the 

 granular masses, and when coagu- 

 lation sets in these are usually found 

 continuous with the threads of fibrin. 



The threads of fibrin are sometimes 

 deposited as long needle-shaped crys- 

 talloids, which are often seen lying 

 in the field free from any granular 



