42 
Sir Everard Home on the 
mucus, and colouring matter, carried into the circulation 
immediately after the process of digestion is completed. 
EXPLANATION OF THE PLATES. 
Plate II. 
In this Plate several small parts of glass micrometers are 
represented, in which the inch is divided into 400 parts in di- 
ameter, which divides the superficies into 160,000 parts ; so 
that every object is magnified 400 times in diameter, and 
160,000 in superficies. 
Fig. 1. In the first square at A, are represented the globules 
of the cerebrum that are predominant. These, it is evident, 
are P art °f a lineal inch. The rest of the micrometers 
of fig. 1 . contain many loose globules of various sizes, and 
fragments of bundles and simple globular fibres of the me- 
dullary substance of the cerebrum in a fresh state, immersed 
in water. 
Fig. 2. represents the same objects in a dried state, when 
the accumulated mucus, and some newly produced globules, 
become visible. 
Fig. 3. represents a very small portion of the medullary 
substance of the cerebrum diluted with w T ater ; also displaying 
fragments of single globular fibres, many loose globules, and 
a portion of the venal branches with valves. 
Fig. 4. represents a small portion of the retina of the human 
eye diluted with water, consisting of loose globules and glo- 
bular fibres of the same size as those of the brain in its various 
