SPIDERS 



107 



are always directed forward, it may readily be seen that they are 

 not used in walking. Into how many parts is the body divided ? 

 To which part are all the legs attached ? Have the children look 

 for the eyes of the spider. Where are they and how many are 

 there ? The eyes of spiders are shining little black spots situated 

 on the upper frontal part of the anterior half of the body, (that part 

 which bears the legs, and is the head and thorax of the spider 

 joined together). The eyes vary in number and arrangement in 

 different kinds of spiders, and vary in size on the individual. 

 The common ground or running spiders have eight eyes (which 

 is the more usual number among spiders) and they are arranged 

 as shown in figure 64. Have the children discover which 

 of the eyes are larger than the others. Have the children 

 look for the jaws (mandibles) of the spider. With a pin press 

 the jaws apart laterally and examine one of them carefully. 

 Each jaw (fig. 64) is composed of a firm, smooth, 

 sharp, pointed tip and a thicker hairy basal part. 

 The tip is the fang, which is thrust into the prej^ 

 and the basal part contains the poison sac. From 

 the poison sac the poison runs thru the fang and 

 out of it thru a tiny hole near the point. Ex- 



•^ Fig. 64. Front 



amine now the spinning organs. A.t the posterior of head of spider 



showing: eyes 



tip of the body may be seen a few small finger-like and mandibles 

 projections, the spinnerets (fig. 65); 

 (some of these are so small and so much 

 concealed by the others that it will be 

 difficult for the children to determine 

 exactly how many there are). From 

 these comes the silk when the spider is 

 "spinning." Each of these little finger- 

 like spinnerets bears on its surface many very small papillae, the 

 spinning tubes. These cannot be seen with the unaided eye, but 



Fig. 05. Spinnerets. 



