THE LIVING STRUCTURES 113 



parts such as sensitive and insect catching plants. How- 

 ever, as a general classification, it is as good as any to con- 

 sider them as either stationary or movable habitations of 

 the cell, just as a house is a stationary habitation of man 

 while a ship is a movable one. 



Some of the simplest structures are mere associations 

 or groups of cells like the micro gromia socialias. These 

 cells understand how to inclose themselves in shells, and 

 stick the shells together, and in that way remain together 

 in a social community. They have already discovered the 

 art of building covers or armours about themselves of 



FIG. 11. Blood-cells, which increase by divi- 

 sion, from the embryo of a young stag. Each 

 blood-cell has originally a kernel, and is globular 

 fa). When they are about to increase, the cell- 

 kernel, or nucleus, first separates into two 

 kernels (b, c, d). The protoplasmic body then 

 becomes pinched in at a point between the two 

 kernels, which become more widely separated 

 from each other (e). Finally a complete sepa- 

 ration between the two parts is effected at the 

 ooint where tfte original cell was pinched in, so 

 that there are now two cells (f). HAECKEL. 



lime and other materials, and the advantage of associat- 

 ing together for offensive and defensive purposes in the 

 struggle for existence. Fig. 12 is a description of this ani- 

 mal taken from a text book on zoology. This cell is 

 similar to the cell heretofore considered under the name 

 of volvox. Man in his first days of development is also a 

 mere cluster of cells, the same as this. After the cluster 

 is formed, then these arrange themselves into layers in 

 the shape of a cup, which is the beginning of the stomach. 

 A wonderful plant or animal, whatever a person may wish 

 to call it, is the Physalia. It is also called the Portuguese 



