THE LIFE-HISTORY OF THE LEUCOCYTE 269 



amount of phagocytosis can thus be secured, and by obtaining 

 increased phagocytosis, increased destruction of micro-organisms 

 can be brought about. Not only may increased phagocytosis 

 be procured by increasing the number of phagocytic leucocytes, 

 but also by increasing the opsonic content of the body fluids, 

 and by increasing the phagocytic activity of the leucocytes 

 themselves. Tunnicliffe has recently shown that the phago- 

 cytic activity of the polymorphonuclear leucocytes can be 

 stimulated both in vivo and in vitro by the newer organic 

 compounds of arsenic such as neoarsphenamin and neosalvarsan 

 in proper concentrations (i in 100,000), In vivo this result is 

 very rapidly obtained, as a rule, within thirty minutes after 

 intravenous injection. Whether this stimulation of the 

 phagocytic activity of the polymorphonuclear leucocytes by 

 the administration of neoarsphenamin and neosalvarsan is 

 of significance in the therapeutic action of these drugs remains 

 for further research to determine. 



Large Hyaline Mononuclear Leucocytes. — These are the 

 largest cells present in normal blood, being about two or three 

 times the diameter of the red blood corpuscle. In them the 

 cytoplasm is relatively more abundant than in the lymphocytes. 

 It stains very faintly with aniline dyes, and being hyaline in 

 appearance is devoid of granules. The nucleus is large and 

 may be round, oval, indented, reniform, or twisted. It stains 

 less intensely than that of the lymphocyte, which this cell 

 somewhat resembles. The nucleus further is usually excentric 

 in position, being near the margin of the cell. The large hyaline 

 mononuclear leucocytes are present in small numbers in normal 

 blood, constituting about 4 per cent, of the total number of 

 leucocytes. 



Along with the typical large hyaline mononuclears are 

 usually enumerated the " transitional " leucocytes, which may 

 be considered to be atypical large hyalines since they possess 

 characters intermediate between those of the true large 

 hyalines and polymorphonuclear neutrophile leucocytes. 



A relative increase and the number of large hyaline mono- 

 nuclears and transitionals is characteristic of protozoal infec- 

 tion. It is almost constantly found in such protozoal infections 

 as malaria, syphilis, yaws, kala-azar, and the trypanosomiases. 

 Another condition in which a relative large hyaline leuco- 

 cytosis occurs — as has been recently shown by Browning — is 

 sympathetic ophthalmia {Irido-cyclitis sympathica). This is 

 a condition much dreaded by the ophthalmic surgeon. It is 

 characterised by the occurrence of a plastic inflammation of 

 the ciliary body leading to loss of vision in an eye, following 

 receipt of a perforating injury in the opposite eye, which itself 

 becomes the seat of a plastic inflammation in the ciliary body. 



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