136 THE MICROSCOPIST. 



a common cell-membrane ; at i, we see three new cells (one of 

 them elongated, and probably about to subdivide) within the 

 parent ; and in each of the two groups at the top and bottom 



Fig. 41. 



of the figure, we have four cells, separated by partitions of in- 

 tercellular substance, but having manifestly originated from 

 one parent cell. 



Fig. 42 represents endogenous cell-growth in cells of a me- 

 liceritous tumor; a, cells presenting nuclei in various stages 

 of development into a new generation; 6, parent-cell, filled with 

 a new generation of young cells, which have originated from the 

 granules of the nucleus. 



The following arrangement of animal tissues is based upon 

 that adopted by Dr. Carpenter. 



1. Simple membrane; homogeneous, or nearly so, employed 

 alone, or in the formation of compound membranes. Its prin- 

 cipal character in extension, but its ultimate structure de- 

 fies the highest powers of the microscope. Examples are seen 



