460 ZOOLOGY. 



ment, because he can remember the words of it. He should 

 always test his understanding of difficult points by trying to 

 express them in words of his own. Many statements, 

 especially descriptive ones, are often difficult to follow unless 

 the accompanying diagrams are studied. These should not 

 be merely looked at, but copied : only thus can you be sure 

 of seeing every detail. Moreover, careful copying is a good 

 training in that accurate observation without which dissec- 

 tion loses much of its value. In copying diagrams, a set of 

 coloured pencils is absolutely indispensable. Although the 

 diagrams have been made as clear as possible in black and 

 white, their clearness can in many cases be increased, and at 

 the same time the trouble of drawing them diminished, by 

 the use of different colours in place of different modes of 

 shading. The " Blaisdell " coloured pencils are recommended, 

 as more readily sharpened and less easily broken than the 

 ordinary cedar-wood pencils ; but they can only be had in 

 four colours, and greater variety than this is often wanted. 

 Both kinds can be obtained through any shop where artists' 

 materials or school appliances are sold. 



The abundance of unfamiliar technical terms is a 

 difficulty with many beginners. These terms fall into two 

 categories. There are ancient terms whose derivation is 

 often so obscure that they are practically meaningless : these 

 terms have to be learnt as a new-comer in any neighbour- 

 hood learns the names of the streets by constant familiarity 

 impressing them on the memory. On the other hand, most 

 modern terms are self-explanatory, if once the meanings 

 attached to a number of Greek and Latin roots are under- 

 stood. For this purpose the following list of some of the 

 commonest roots will, we hope, prove useful. We strongly 

 recommend the student to take note of all such roots, as he 

 comes across them ; it will save him more trouble later on. 



ana, up. 



arohi, ancient, primi- 

 tive. 



blast, develop. 

 cephal, bead. 



GREEK ROOTS. 



chloro, green. 

 ckromo, colour. 

 coel, cavity. 

 derm, skin. 

 ecto, outside. 



endo, inside. 

 entero, intestine. 

 epi, upon. 

 gastro, stomach. 

 haemo, blood. 



