298 AQUATIC MICROSCOPY FOR. BEGINNERS. 



they are often sufficiently transparent to be easily 

 studied without the. troublesome cleaning process. 

 The facets of compound eyes frequently have long 

 hairs between them. The eyes of spiders are several, 

 and are arranged on the top of the head. If the 

 spider is small, place the whole body under a low 

 power, and view as an opaque object; otherwise cut 

 into parts to suit. The eyes have a wicked look as 

 they brightly gleam in the reflected light. 



5. PftOBOSCiDES OF INSECTS are as numerous and 

 varied in structure as the insects. They should be cut 

 off close to the body, squeezing the insect to force out 

 the parts if necessary. Examine in water or in glycer- 

 ine, covering with a thin-glass square or circle as al- 

 ready explained. The tongue or proboscis of a but- 

 terfly is interesting. The latter is usually visible as a 

 small coil just under the front of the head. It may be 

 unrolled with a needle, and then cut off close to its 

 point of attachment. It is composed of two longitudi- 

 nal parts which separate easily. Examine in water or 

 in Canada balsam, and notice the one or more rows of 

 little projections forming conspicuous barrel-shaped 

 objects on the tip of some butterflies' tongues. These 

 are supposed to be either papillee of taste, or imple- 

 ments with which to tear open the nectar glands within 

 the flower. 



6. Eggs of Insects cannot always be obtained when 

 wanted, but they make beautiful objects. They 

 should be viewed as opaque bodies, unless they are 

 found after the larva has escaped, when they may 

 have become transparent and can be examined in 

 water. The surface-markings are in a great variety 

 of patterns. 



