200 JOHN STEPHENS LATTA 



of lymphoid hemoblasts into cells of the granuloblastic or eryth- 

 roblastic line of development may be conceived as dependent 

 upon the closeness of association between the blood vessels and 

 the lymphoid hemoblasts, the slowness of the current of the 

 blood stream, and upon the thinness of the vascular walls. If 

 the association between the lymphoid hemoblasts and the blood 

 vessels is very close and the conditions necessary for the transu- 

 dation of materials from the blood stream (plasma) are very good, 

 erythropoiesis occurs. If the association is not so close or the 

 transudation conditions present to a lesser degree, granulopoiesis 

 results. 



In conclusion, the writer wishes to express his appreciation 

 of the courtesy of the Department of Histology and Embryology, 

 Cornell University, in furnishing facilities and materials for this 

 study, and also of the generous help and encouragement of 

 Dr. B. F. Kingsbury. 



BIBLIOGRAPHY 



Arnold, J. 1895 Zur Morphologie und Biologie der Zellen des Knochenmarks. 



Arch. f. path. Anat. u. Phys., Bd. 140, S. 411-448. 

 Badertscher, J. A. 1913 Muscle degenerati(/n and its relation to the origin 



of eosinophil leucocytes in amphibia (S. atra). Am. Jour. Anat., 



vol. 15, pp. 69-86. 



1915 The development of the thymus in the pig. II. Histogensis. 



Am. Jour. Anat., vol. 17, pp. 437-493. 

 BizzozERO 1883 Formation des Corpuscles sanguins rouges. Arch. Ital. de 



Biologie, T. 4, pp. 309-345. 

 BRtJCKE 1851 tlber den Bau und die Bedeutung der Peyer's schen Driisen. 



Denksch. der Wiener Akad. (quoted from Hartmann). 

 Burnett, S. H. 1917 The clinical pathology of the blood of domesticated 



animals. Macmillan Co., New York. 

 CzERMACK, N. 1893 Einige Ergebnisse liber die Entwickhmg, Zusammen- 



setzung, imd Function der Lymphknotchen der Darmwand. Arch. 



f. mikr. Anat., Bd. 42, S. 581-632. 

 Danchakoff, V. 1909 ITber die Entwicklung des Knochenmarks bei d«n 



Vogeln, usw. Arch. f. mikr. Anat., Bd. 74, S. 855-926. 



1915 The wandering cells in the loose connective tissue of the bird, 

 and their origin. Anat. Rec, vol. 10, pp. 397-414. 



1916 The equivalence of haematopoietic anlages. I. Am. Jour. 

 Jour. Anat., vol. 20, pp. 255-308. 



1918 £^ell potentialities and differential factors, considered in rela- 

 tion to erythropoiesis. Am. Jour. Aat., vol. 24, pp. 1-35. 

 1918 The equivalence of haematopoietic anlages. II. Amer. Jour. 

 Anat., vol. 24, pp. 127-189. 



