GENERAL OBSERVATIONS 45 
ficial layers of the cells composing it are hard and horny, 
while the deeper layers are soft and protoplasmic. These 
latter form the so-called Rete Mucosum of Malpighi. 
Commencing from below and proceeding upwards, we 
find that the lowermost cells of the rete mucosum, those 
Fic. 28.—VerticaL Section or Eprpermis (Human). (AFTER 
RanvIER.) 
A, The horny layer of the epidermis ; B, the rete mucosum ; a, the columnar 
pigment-containing cells of the rete; b, the polyhedral cells; c, the 
stratum granulosum; d, the stratum lucidum ; e, swollen horny cells ; 
J, the stratum squamosum. 
that are set immediately on the corium, are columnar in 
shape. In animals that have a coloured skin these cells 
contain pigment granules. Directly superposed to these 
we find cells which in shape are polyhedral. Above them, 
and forming the most superficial layer of the rete mucosum, 
