228 RALPH DOUGALL LILLIE 



with oxyphil cytoplasm without making it clear whether all the 

 cells were granular or not. Downey ('13) describes in Amblys- 

 toma special leucocytes containing many fine purplish-pink 

 granules (Wright's stain) which he concludes are azurophil, dif- 

 fering, however, from the azurophil granules of the lymphocytes, 

 and being homologous with the granules of the special leucocytes 

 of mammals. Werzberg ('11) finds in eight species of Urodela 

 and eight species of Anura that the special leucocytes are non- 

 granular, save in Salamandra maculosa and Rana esculenta in 

 which he describes fine azurophil granules. In these same two 

 species Niegelewski ('94) describes fine granules which are neu- 

 trophil to triacid. Griinberg ('01) gets the same results as 

 Werzberg. Freidsohn ('10) and Weidenreich ('11, p. 75) state 

 that granules are lacking in the special leucocytes of Amphibia. 

 In Rana aurora and in Batrachoseps attenuatus I was unable to 

 find any granules in the special leucocytes. 



In larvae of 37- to 40-mm. total length, that is, larvae which 

 show the beginning of hind-limb buds and measure 15 to 16 mm. 

 from the snout to the anus, all of the above-described cell forms 

 may be found in the loose connective tissue surrounding the bile 

 duct. In the mesonephros there may be seen small areas in which 

 all the cells are lymphocytes, while surrounding these islets all 

 types of white cells are mixed. As yet, few leucocytes occur in 

 the vessels, nor is there any definitive erythropoiesis. As in 

 Bufo vulgaris (Mietens, '10), there is no interstitial hemato- 

 poiesis in the liver of B. halophilus up to this stage. 



In closing, I take pleasure in thanking Prof. F. M. MacFarland 

 for his aid and suggestions and for the use of his private room in 

 the Hopkins Marine Station during the summer of 1916. 



SUMMARY AND CONCLUSIONS 



1. The primitive blood-cells arise from the ventral cell mass. 

 Some isolated cells are found in various parts of the mesenchyme. 



2. These cells lose their yolk by intracellular solution, dif- 

 ferentiating at the same time into primitive erythroblasts and 

 large lymphocytes. 



