The microscopic observations of lymphatic capillaries in the living mammal has been carried out for the past 5 years by means of transparent chambers permanently installed in the ears of rabbits. In the'round table'chamber, in which a hole is cut clear through the ear and a celluloid table inserted in the gap, the regeneration of new tissue takes place in a space approximately 6.5 mm. in diameter, the thickness of which is controlled by means of small celluloid buffers glued to the surface of the table on which the mica cover slip rests (Clark et al.,'30). Since in such chambers the thickness of the new tissue with its circulating blood vessels (40 p to 75p) plus that of the mica cover slip (60 p to 70 p) is about equal to the thickness of a no. 1 glass cover slip, the finest cytological details can be studied at high microscopic magnifica t ions.

Descriptions of the manner in which new blood vessels invade the table space and of the remodelling of the primitive capillary plexus into a stable vascular pattern, have been given (Clark et al.,'31). The growth of new lymphatics into the table space and the morphological characteristics of lymphatic capillaries in the living mammal have also been described (Clark and Clark,'32,'33). By means of prolonged