1894.] MICROSCOPICAL JOURNAL. 369 



much flattened and deprived of their coloring matter. 

 The experiment I have here described was first made by 

 N orris, of England, who thought he had discovered 

 a new element in the blood, and proposed the awkward 

 name " Invisible corpuscles of the blood." He evidently 

 did not take into account the fact that the platelets were 

 artificial products caused by the breaking up of the 

 blood corpuscles. Norris's experiment is valuable, liow- 

 ever, inasmuch as it enables us to produce them in large 

 numbers in a short time. 



The question now arizes, what are platelets ? I may 

 state that without doubt they are products of the red 

 blood corpuscles caused by their breaking up into frag- 

 ments of varying sizes. My reasons for this belief are 

 the following : 



1. In specimens of fresh blood transferred at once to 

 the microscope I have seen, when the red blood cor- 

 puscles were distinctly crenated, knobs hanging upon 

 the corpuscles by means of a slender pedicle. These 

 knobs, after the pedicles break, float freely in the sur- 

 rounding serum, exhibiting a slightly angular contour and 

 all the features of blood platelets. 



2. If the blood of persons with an impaired consti- 

 tution is prepared and kept for a few days being ex- 

 amined daily we shall in a short time, beginning perhaps 

 on the second or third day, notice clusters of platelets 

 which judging from their grouping,must have arisen from 

 the breaking up of red blood corpuscles. 



3. If we treat fresh blood with glacial acetic acid 

 diluted with equal parts of water, the red blood corpus- 

 cles are immediately transformed into large flat and 

 pale plates as already described, with blood platelets 

 varying in size from the minutest granules up to those 

 of ordinary size. At the same time, in the surrounding 

 blood plasma numerous platelets have appeared. 



