ORAL EQUIPMENTS. 59 



Strange as it may seem, it is a fact. Analogous in chemical 

 constituents to " chitine " rather than dentine, each fibre 

 develops from a vascular and persistent pulp, and erupts in 

 the same way as a tooth. Our diagram will help to explain 

 the manner in which it comes into use, and performs its 

 functions. 



I will describe the structure in Mr. Tomes's words, 

 vide "Dental Anatomy." "From the upper jaw of an 

 adult Whalebone Whale, there hang down a series of plates 

 of Baleen, placed transversely to the axis of the mouth, but 

 not exactly at right angles of it. 



"The principal plates do not extend across the whole 

 width of the palate, but its median portion is occupied by 

 subsidiary smaller plates. The whalebone plates are frayed 

 out at their edges, so as to be fringed with stiff hairs, and 

 their frayed edges collectively form a concave roof to the 

 mouth, against which the huge tongue fits, so as to sweep 

 from the fringes whatever they may have entangled. The 

 Whale in feeding takes in enormous mouthfuls of water 

 containing marine mollusca; this is strained through the 

 Baleen plates, which retain the Peropods and other small 

 creatures, while the water is expelled. Each plate consists of 

 two dense but rather brittle laminae, which inclose between 

 them a tissue composed of bodies analogous to hairs. By the 

 process of wear the brittle containing laminae break away, 

 leaving projecting from the edge the more elastic central 

 tissue, in the form of stiff hairs." 



And now, Ladies and Gentlemen, I hope I have not too 

 severely taxed your patience, and also that my remarks may 

 tend to show that lessons elevating to the mind may be 

 learned even from the study of teeth or " dry bones." 



In my next paper on this subject, which will be the last 

 of the series of three sections, I hope to deal with the 

 deciduous teeth at greater length, and show some of the 

 histological characters of the various tissues. 



