USE OF THE MICROSCOPE IN ZOOLOGY. 69 



tube by the union of their grooves; the juices of the 

 flowers are sucked up by means of the proboscis, but 

 what the precise mechanical action may be is a matter 

 of doubt. On the tips of the haustella of some of 

 the Lepidoptera are small papilliform bodies, project- 

 ing at a considerable angle ; it has been conjectured 

 that they are organs of taste, but nothing is known as 

 to their functions. 



In the flea, the mandibles are represented by a . 

 pair of very sharp, razor-like instruments, which are 

 situated on each side of the tongue ; the maxillae, 

 which appear in the form of a pair of elongated 

 flattened bands, serve as sheaths for the mandibles. 

 The labial palpi also, in the flea, are cutting instru- 

 ments. You must not expect to be able to make out 

 all these details without a good deal of patient care, 

 and without many failures at first ; but persevere, and 

 you will be rewarded by success in time. I would 

 recommend you to begin with the study of the struc- 

 ture of insects' mouths, by selecting some large beetle, 

 as a cockchafer. After you have killed it, cut off the 

 head, and examine the various parts with a low power 

 of the microscope. Place the head in a gutta-percha 

 trough of water, and with dissecting-needles separate 

 the component parts, viewing the insect's head first 

 on the dorsal aspect, then on the ventral ; be careful 

 to notice the relative position of the parts, and do 

 not proceed to the examination of another species 

 till you have thoroughly mastered one. You lose 

 no time by such a proceeding ; oh the contrary, you 

 are really saving time, because the knowledge acquired 

 by such thorough kind of work will so imprint itself 

 on your mind, that you will be saved much time that 

 would otherwise be lost, from repeated attempts to 

 verify some point which a careful preliminary study 

 would have settled at a glance. 



