SYSTEMATIC SYNTHESIS OF TISSUES INTO ORGANS. 315 



for them to perform. That office is performed by some 

 part, and many arguments drawn from the structure of 

 the ear in lower animals go to establish the statement. 



882. THE EAR MIGHT BE CONSTRUCTED by tracing 

 out the nerves of hearing from their ganglia till an ap- 

 propriate place is found in the outer walls of the head 

 for suspending the nerves and their cells in contact with 

 an enclosed fluid ; in front of which appropriate media, 

 the middle and outer ears should be constructed for re- 

 ceiving and transmitting the extremely delicate vibra- 

 tions of the most sensitive of all material things, the air, 

 capable of vibrating in three modes, expressive of inten- 

 sity, pitch, and quality, through a great range of each. 



883. IN THE STRUCTURE OF THE EAR all six (JR., dr., 



Si., M., JV.y /8e.) tissues are required. 



884. Remark. There ARE PEW CAUSES OP DERANGEMENT OP THE 

 EAR. Ear-wax is sometimes allowed to collect and harden in the tube ; 

 a little sweet oil dropped into it several times and washed out with cas- 

 tile soap and warm water will suffice to remove that difficulty. Colds 

 are very apt to affect hearing, through the Eustachian tube ; they must be 

 very carefully avoided if they affect hearing. If it is thus permanently 

 stopped the opening can sometimes be regained by passing a tube into 

 it. If that cannot be done, sometimes hearing can be regained by making 

 an opening in the external membrane. If a watch placed against the 

 head can be heard, there is hope. Throat diseases, scarlet fever, etc., 

 are very liable to leave children with a hardness of hearing. To prevent 

 that result, and to prevent still worse effects, great care should be taken 

 during recovery from such diseases to avoid taking cold ; and if it occurs, 

 and care is taken, the trouble will usually be outgrown, or, if it is not, 

 it will ingrow deeper. 



SECTION VL 



Circulatory Organs. 



885. The Circulatory Organs are of five kinds: 

 Capillaries, Veins, Arteries, Hearts, and Lymphatics. 



882. How ? 888. What tissues required --? 884. What are to ? What the 

 effect of taking cold upon hearing? 885. Class circulatory organs. 



