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HOWELL. [Vol. IV. 



to find all intermediate stages in the process as shown in 

 Fig. 1 6. They are derived always from the third variety or 

 third stage in the life of the uninucleated leucocyte, the 

 elongated nucleus breaking up into the smaller fragments ; 

 and it is not difficult to find cells such as are shown in the 

 figure in which the fragmentation is going on. According to 

 this view, the different varieties of leucocytes found in the 

 blood are in reality different stages in the life-history of the 

 white corpuscle, and pass one into the other. To complete 

 the life-history, one other stage must be described, — that of 

 the disintegration of the multinucleated form. A close exami- 

 nation of the multinucleated cells, especially when in the act 

 of disintegrating, has impressed me with the belief that the 

 fragmented nuclei persist for a certain time in the circulation 

 as the blood plates, though doubtless the blood plates also, 

 sooner or later, go into solution. 



This view of the origin of the blood plates is not new. 

 Gibson (33) supports it, and gives some evidence in its favor; 

 and Hlava (47) especially has given a number of arguments — 

 none of which, however, are very conclusive — to prove this 

 derivation. One is led, at first, to such a theory by noticing 

 the very striking resemblance between well-preserved blood- 

 plates and the fragmented nuclei as far as size, shape, and 

 general appearance are concerned. This resemblance is still 

 further increased when the blood plates are examined in the 

 blood of an animal which has been repeatedly bled. Under 

 such conditions, one gets, or may get, blood plates which have 

 one or more granules within them staining more deeply than 

 the rest of the plate, and resembling very closely the chromatin 

 granules found in the fragmented nuclei of the leucocytes, as 

 shown in Fig. 6. Something similar to this seems to have 

 been obtained by Afonassiew. We may suppose in this case 

 that the increased activity in the processes going on in the blood 

 in connection with the regeneration, not only of its formed 

 elements, but of its characteristic prcteids,. have led to a more 

 rapid breaking down of the leucocytes, and that some of the 

 fragmented nuclei are liberated as blood plates before reaching 

 the usual degree of maturity. There is, moreover, a very close 

 similarity in the way in which the fragmented nuclei and the 

 blood plates stain. As far as I have been able to test them, 



