88 



FIRST LESSONS IN /OOLOGY 



for mastication. Where mastication is necessary there is 

 an expansion of the alimentary canal called crop or craw, 

 which acts as a reservoir for the hard seeds or grains, 

 and further along the gizzard, which with its strong 

 muscular wall antl hard inner coat, assisted by the small 

 stones picked up in eating, sufficiently grinds up the 



50. Fig. 51. 



Yir,. 50. — llcail and mouth parts of honey-bee; note the sliort trowel-like 

 niandililes tor niouhlinL,' wax when building comb, and the extended 

 [irolioscis for sucking flower nectar. (Much enlarged; from specimen.) 



I'lc. 51. — Piercing and sucking beiik of the mosquito (female) dissected to 

 sIhjw its parts. (Much enlarged; from specimen. ) 



food. Among mammals the same large e.xtent of variety 

 in the mouth structure exists as among insects and birds. 

 Compare the teeth and other mouth parts of a rat, 

 beaver, cat, pig, horse, sheep, and man, noting how they 

 vary in number, size, and form, and then consider how 

 each is used in the process of eating. 



To understand the process of digestion some knowledge 

 <_if the nature of food substances is necessar}'. In consid- 



