FISHES 137 



rather than as organs of hearing. Fishes from which these internal 

 ears have been removed are unable to maintain their equilibrium. 



Some fishes have special organs that serve as tactile organs such 

 as are found on the under side of the head of a cod (Fig. 108) and also 

 on the headof bullheads (Fig. 101). Along each side of the body and 

 tail of fishes is a series of little openings or pores which form what is 

 known as the lateral line (Fig. 108). These organs are supposed to be 

 principally organs of touch. 



FIG. 101. Bullhead. (Goode.) 



104. Reproduction and life history. The flowers of seed 

 plants are devoted to the production of seeds which, in 

 turn, produce new plants of the same kind (P. B., 83). 

 Likewise in fishes there are special organs the sole function 

 of which is the production of new individuals. The organs 

 of fishes which may be said to correspond in function to the 

 stamens and pistils of flowers are the ovaries (Fig. 98) and 

 spermaries. In the ovaries are produced many egg-cells, 

 and the mass of eggs in the ovary of a fish is often called the 

 roe. In order that an egg may develop it must first be fer- 

 tilized by a sperm-cell from the spermary of a male fish. This 

 process usually occurs in the water after the ripe eggs and 

 sperm-cells have been extruded from the ovaries and sper- 

 maries of the parent fishes. 



You will recall the fact that the pollen tube containing a 

 sperm-nucleus makes its way into an ovule and that the 



