VARIETIES OF LEUCOCYTES. 425 



chambers, but we have at present very few facts concerning 

 its distribution. It is certainly sometimes present in excess 

 in the blood of uraemic patients (Griinbaum). 



VI. The Coarsely Gramilar Basophil Cell. 



This is one of the largest and most striking forms of 

 leucocyte. It is in figure usually a somewhat flattened 

 sphere ; its nucleus is round and central. The granules 

 with which the cell-body is densely laden are large, about 

 1 n diameter, and are, unlike the oxyphil granules, not highly 

 refracting. The cells themselves are more fragile than 

 most leucocytes ; they break or burst, and let loose their 

 granules under even careful modes of preparation. They 

 have for this reason been sometimes termed "explosive 

 cells ". They are not amoeboid, nor, as far as is known, 

 phagocytes. They form about a tenth of the collection of 

 Iree cells in lymph and serous fluids. They are completely 

 absent from the blood. They are identical, as far as their 

 granulation is concerned, with certain fixed cells which are 

 numerous in the connective tissue around lymph and blood- 

 vessels — Ehrlich's mast zellen. Islets of such cells can be 

 found in the mesentery accompanying certain blood-vessels. 

 They are numerous also in the mucosa of the small in- 

 testine. To obtain striking specimens of the coarsely 

 granular basophil leucocyte no better locus can be chosen 

 than the pericardial chamber of the rat. In the moisture of 

 that sac extremely fine examples of the cell are easily found. 



It is clear from the foregoing that the morphological 

 differences between these various leucocytes are marked 

 enough. Some observers hold that the various forms are 

 not distinct species of cell at all, but are merely the various 

 aspects assumed by one and the same pleomorphic organism 

 in successive phases of its individual life history. Such a 

 speculation suggests itself very naturally, but is not so easy 

 either to prove or to disprove. The "pleomorphism" view is 

 pushed to its extreme by those pathologists who assert that 

 leucocytes can arise by transformation of fixed connective 

 tissue corpuscles, and that then after wandering through a 



