DISSECTION Of GRASSHOPPER. 



simple eyes or ocelli. How many of these do you find, and 

 how are they arranged ? 



On the front of the head, below the eyes, is a broad fold, 

 the clypeus, to which is attached a movable upper lip 

 (labrum) covering the mouth in front. Near the eyes arise 

 two long, slender feelers or antennae. Could they be re- 

 garded as jointed appendages ? 



On the lower side of the head is the mouth, surrounded 

 by a series of appendages or mouth-parts. Beginning be- 

 hind, remove these one after another with forceps and 

 needle. The most posterior is the lower lip or labium. 

 It is in reality double, and consists of the united basal 

 joints and, arising from these on either side, a several-jointed 

 palpus. Draw the labium X 10, and then take off and draw 

 the pair of appendages, the maxillae, next in front. Notice 

 that in these the basal joints are enlarged, one forming a 

 sharp cutting-organ, the other a more fleshy portion to hold 

 the food in position. The terminal parts form a palpus, 

 somewhat similar to the labial palpus. Still further in 

 front come the jaws or mandibles. Move these with the 

 forceps. Do they work in the same way that your own 

 jaws do ? Draw them, and then draw front and side views 

 of the head, labelling all the parts. 



Have you found any traces of segments in the head ? 

 How many pairs of jointed appendages have you found ? 

 According to Savigny's law, how many segments* must 

 there be ? 



INTERNAL STRUG TUBE. 



The internal structure of the grasshopper in its larger 

 features is readily made out. Select a large female for the 



* Study of the embryos of some insects makes it probable that there 

 is one more segment in the head than is shown by Savigny's law. 



