244 ELIOT R. CLARK AND ELEANOR LINTON CLARK 
mation. Such growth on the part of blood-vessels and lym- 
phatics, however, did not appear to be in excess of the normal 
rate of growth. 
The manner in which lymphatic capillaries served as paths 
by which the migrating leucocytes were enabled to reach the 
7 a aA 
Fig. 13 Sketches of cells from a fixed specimen. Five hours after the injec- 
tion of croton oil, this larva was examined and found to be in the stage in which 
a ring of sessile leucocytes was in process of formation. The tadpole was fixed 
in Bouin’s fluid, the whole tail was stained in alum haematoxylin, counterstained 
in eosin, orange G, and aurantia, dehydrated, cleared in xylol, mounted in damar. 
The sketches were made with the oil-immersion lens. A. Amoeboid leucocyte. 
B and C. Sessile leucocytes with processes. D. Normal connective-tissue cell 
outside injured area. E. Connective-tissue cell near the croton-oil globule. F. 
Connective-tissue cell in close proximity to the croton oil, showing extreme type 
of injury (chromatin scattered through the cell). 600. 
scene of action more quickly has already been described. There 
are steps in the migration of such a leucocyte through the wall 
of a lymph-vessel in which it is easy to be deceived into the 
belief that the proliferation of an endothelial leucocyte is taking 
place, for the leucocyte often comes out of the vessel near the 
point where a nucleus is located. But continuous observation 
