IV.] 



THE VASCULAR SYSTEM. 



93 



points, blood-corpuscles make their appearance in the pro- 

 cesses also, the central portions of which become at the same 

 time liquefied. 



By the continued widening of the connecting processes and 

 solution of their central portions, accompanied by a corresponding 

 increase in the enveloping nucleated cells, the original proto- 



FIG. 33. 



SURFACE VIEW FROM BELOW OF A SMALL PORTION OF THE 

 POSTERIOR END OF THE PELLUCID AREA OF A THIRTY-SIX 

 HOURS' CHICK. To illustrate the formation of the blood- 

 capillaries and blood-corpuscles, magnified 400 diameters. 



b.c. Blood-corpuscles at a nodal point, already beginning to 

 acquire a red colour. They are enclosed in a layer of proto- 

 plasm, in the outermost part of which are found nuclei, a. 

 These nuclei subsequently become the nuclei of the cells 

 forming the walls of the vessels. The nodal groups are 

 united by protoplasmic processes (p*pr\ also containing 

 nuclei with large nucleoli (ri). 



