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 

 rind that the lowermost cells of the rete mucosum, those 



B 





Fig. 23.— Vertical Section of Epidermis (Human). (After 

 Ranvier.) 



. The horny layer of the epidermis ; B. the rete mucosum ; (7, the 

 columnar pigment-containing cells of the rete; b, the polyhedral 

 cells ; c, the stratum granulosum ; d. the stratum lucidum ; e, 

 swollen horny cells; /, 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, 



