WHAT tS A SPIDER? 7 



quite true ; but a good microscopist likes to know what to look 

 for, and what is most interesting, Some have made a study of 

 the web alone, and it is astonishing what a difference there is in 

 each family. Then, again, there has been some discussion how 

 the young of a spider is sustained. Mr. Samborn states that they 

 are suckled, and has seen milk oozing out of the spinnerets. Then 

 there are the spinnerets, the feet, which have two claws, and a 

 serrated appendage, so as to enable them to slide down on the 

 web. The head is exceedingly interesting ; the eyes are simple 

 ocelli and are a fascination to the embryologist ; also observe the 

 mandibles, a basal thick one, and a terminal one, curved and 

 sharply pointed, which is connected with the poison-gland. 

 Some authors consider these modified antennae. Then comes the 

 maxillary palpi, which terminates in the female in a small hook. 

 The tracheae and stigmata of the latter, and also the ovipositor. 

 There are four spinnerets on each side, thus showing that their 

 habits and structure offer a very wide scope for industrious work 

 to the microscopist. 



I ought not to conclude my address without speaking of the 

 microscopical technique, which requires some practice and atten- 

 tion. Even to mount the feet of a spider, one difficulty is to get 

 them free from dirt and hair. 



First, as to the bleaching. This may be done in several ways, 

 either with hydrochloric acid and chlorate of potash, or by a 

 simple solution of potash {Liquor Potasses of the British Pharma- 

 copoeia), or a solution of chlorate of soda or lime ; but any of these 

 chitinous arachnidse or acari must be watched, as if left too long 

 in solution they break up entirely. It is better to take the speci- 

 men out of the solution before it gets quite clear than leave it too 

 long, as whilst it is being washed it continues bleaching ; it 

 should now be washed in distilled water to free it from the drug, 

 then in a little spirit, then in some turpentine, and again in xylol 

 or spirit, and lastly in clove oil. For mounting I prefer the 

 balsam dissolved in turpentine, but great care must be taken to 

 touch the specimen with a small piece of filter paper whilst on 

 the section-lifter, so as to absorb and free it entirely from the clove 

 oil, or it will be cloudy when examined under the microscope. 



