58 EPITHELIAL CELLS 



showing striated distal border from which in r> 3 pseudopods are 

 protruded. 



E 1 , ciliated epithelial cell from mouth of frog : E' 2 , E 3 , similar cells 

 from windpipe of dog. 



F 1 , parenchyma cell from root of lily, showing nucleus (#) vacuoles 

 (vac), and cell-wall : F", a similar cell from leaf of bean, showing 

 nucleus, vacuoles, cell-wall and chromatophores (chr}. 



(B, D 1 and E 1 , after Howes : c, E 2 , and E 3 , after Klein and Noble 

 Smith : D 2 , D 3 , after Wiedersheim : F 1 , after Sachs : F' 2 , after Behrens. ) 



coloured by a pigment called h&moglobin, and provided 

 each with a large nucleus (nu) which, when the corpuscle is 

 seen from the edge produces a bulging of its central part. 

 These bodies may be compared to Amoebae which have 

 drawn in their pseudopods, assumed a flattened form, and 

 become coloured with haemoglobin. 



In the blood of mammals, such as the rabbit, dog, or man, 

 similar leucocytes occur, but their red blood corpuscles (c 3 , c 4 ) 

 have the form of biconcave discs and are devoid of nuclei. 



In many animals the leucocytes have been observed to 

 ingest solid particles (c 1 ), to multiply by simple fission (B 4 ) 

 and to coalesce with one another forming plasmodia (B 2 ) 



(P- 52). 



The stomach and intestines of animals are lined with a 

 sort of soft slimy skin called mucous membrane. If a 

 bit of the surface of this membrane in a frog or rabbit for 

 instance is snipped off and "teased out," i.e., torn apart 

 with needles, it is found when examined under a high power 

 to be made up of an immense number of microscopic bodies 

 called epithelial cells, which in the living animal, lie 

 close to one another in the inner layer of mucous mem- 

 brane in something the same way as the blocks of a wood 

 pavement lie on the surface of a road. An epithelial cell 

 (D 1 , D 2 ) consists of a rod-like mass of protoplasm, contain- 

 ing a large nucleus, and is therefore comparable to an 



