Science progress. 



No. 12. February, 1895. Vol. II. 



VARIETIES OF LEUCOCYTES. 



PERHAPS recently more than ever has minute atten- 

 tion been given to the structure and behaviour of 

 wandering or free cells, and many of the problems offered 

 by the leucocyte have become familiar to every anatomist 

 and physiologist. It may be useful to attempt a succinct 

 description of some of the recent facts elicited, and of the 

 views enunciated by various authorities. 



By "leucocyte" it is now customary to mean any 

 vagrant cell of the organism, not merely a cell whose 

 habitat lies in blood and lymph, but also the cells which 

 haunt the serous (ccelomic) chambers and the intercellular 

 interstices of the tissues. It was at one time tacitly as- 

 sumed that the wandering cells in each and all of these 

 localities were actually identical (1). It is now well re- 

 cognised that between the wandering cells in various 

 localities considerable and specific differences exist ; and 

 that even in one and the same locality a mixture of wander- 

 ing cells distinctly differing one from another in morpho- 

 logical characters co-exists, although at the same time each 

 of the various cell-forms appears to possess a region of 

 distribution more or less proper to itself, a habitat of its 

 own. 



The varieties of leucocytes now generally recognised to 

 be separable are the following (2) : — 



I. The lymphocyte or small hyaline cell. 



II. The large hyaline cell. 



30 



