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The blood of the American Amblystoma (A. punctatum) is very 

 favorable material for the study of these two questions. The cells 

 are very large and they are easily preserved by almost an}- of the 

 commonly used haematological methods. 



The lymphocytes vary all the way from a comparatively small 

 cell having a very narrow cell- body, to very large cells with abundant 

 protoplasm which correspond to the so-called 'large mononuclears' 

 of other animals. The smaller lymphocytes are usually more baso- 

 philic than the larger ones. The largest cells retain a considerable 

 amount of the original basophilic 'spongioplasm', but it is arranged 

 in the form of an irregular network, or in irregular patches of finely 

 granular flaky material which is more basophilic than other portions 

 of the cytoplasm. The nuclei of these large cells are round, oval, 

 kidney-shaped, or ring-shaped, and sometimes the ring is indented 

 on one side (fig. 1). Other cells, identical in cytoplasmic characters 

 and internal nuclear structure with the ones just described, have a 

 nucleus which, in external form, is much more complex. Figures 2 

 to 5 give an idea of the variations in shape of these nuclei. Many 

 intermediate stages show how these complex nuclei are formed from 

 the ring-shaped nucleus (contra Maximo w for Axolotl). In figure 2 

 we see that the 'ring' is becoming lobulated, and that there is a deep, 

 sharp indentation on one side of it. Such an indentation may gradually 

 become deeper and finally break through into the central space. This 

 will result in nuclei like those of figures 3 and 4. Figure 5 shows 

 another form of nucleus which is frequently met with. 



Calls like the ones shown in figures 3 to 5 are the typical poly- 

 morphonuclears of this animal. They are connected by all possible 

 intermediate stages with the large mononuclear lymphocytes (fig. 1). 



When a dry smear of this blood is stained in Wright's blood stain 

 (a EoMANOwsKY Combination containing azure) many of the smaller 

 and medium-sized lymphocytes, and practically all of the 'large 

 mononuclears ' and polymorphonuclears, are seen to contain a variable 

 number of granules. Many of the smaller lymphocytes do not contain 

 them, but they are present in nearly all of the larger lymphocytes. 

 As differentiation proceeds the cells become, on the average, less 

 basophilic, but the number of granules is increased. The degree of 

 basophilia, however, is quite variable, some of the largest lymphoid 

 cells (large mononuclears fig. 1) having a strongly basophilic cyto- 

 plasm, while in others the cytoplasm is almost colorless, excepting 



