178 EYEXINGS AT THE MICROSCOPE. 



quently seen separate a considerable "way up. Hence 

 you would probably infer that the organ consists of 

 two equal and consimilar halves, united longitudinally. 

 And so, indeed, it does ; and these halves are the rep- 

 resentatives of the maxillce or lower jaws of the Beetle, 

 being thus greatly developed at the expense of almost 

 all the other parts. The upper lip and the mandibles 

 are discernible onlv in the form of three most minute 

 plates ; the labial imljpi are large and prominent,— 

 those well-haired points that project in front of the 

 head, one on each side of the sjDire. Tliis spiral form 

 of the maxillce is called antlia. 



It is not, however, y^vj easy to fix it in an extended 

 condition on a slip of glass, so as that it shall lie flat 

 throughout its whole length, without injuring the parts 

 or so agglutinating them together, that their structure 

 is concealed or distorted, and in either case unfitted for 

 microscopical examination. The specimen which I have 

 prepared, fi-om the mouth of the Small Garden "Wliite 

 Butterfly, is stretched, and fixed in balsam, and will I 

 think show you the structure under a high power very 

 well. 



Before we examine it, hoM'e-vcr, I will cite you the 

 description of one of the most eminent of microscopical 

 anatomists, Mr. Newport. He considers each maxilla 

 to be composed of an immense number of short trans- 

 verse muscular rings, which are convex externally and 

 concave internally, the two connected organs forming a 

 tube. Within each there are one or more large trachem 

 connected with the tracheoi in the head. The inner or 

 concave snrlace which forms the tube is lined Avith a 

 very smooth membrane, and extends along the anterior 

 margin throughout the whole length of the organ. Al 



