1892.] THE MICKOSCOPE. 225 



loi. Does the cysticercus ever develop? What disease is 

 caused by it? 



A cysticercus is the larval form of the tape-worm. The eggs 

 of the mature worm eaten by a hog or ox produce measley meat 

 — that is, full of cysticerci ; this meat eaten by man produces tape- 

 worm. A cysticercus consists of a tape-worm head attached to a 

 small bladder (cyst) containing fluid (serum). Cysticerci occa- 

 sionally produce fluid tumors in the brain, kidney, etc., of man. 



1 02. Why does paper from hornets' nests ^ when used for 

 wads^ keep a gun cleaner than ordinary paper so used? 



Paper from hornets' nests contain sand, mud, or masticated 

 wood, and these substances possess the scouring qualities. 



103. What is the office of plant hairs? 



Plant hairs are outgrowths from the epidermis and assist the 

 latter in protecting the -plant from naturalenemies. 



104. Can different specifnens of tan?zed leather be distin- 

 guished microscopically ? 



Attention to li^ir roots and thickness of epidermis, etc., would 

 probably assist ill the identification of the different tanned skins. 



105. Do the spinnerets of spiders vary in number? Are all 

 webs co7nposed of 4 threads? 



The spinnerets are usually 6 in number. The filaments from 

 these fuse together to form a single thread ; occasionally a more 

 or less coherent double thread is produced. Some of the spin- 

 nerets produce the hard, radiating threads of the web ; others add 

 the viscid drops to the circular threads. 



106. Rev. y. G. Wood writes^ '''•An insect ?zever grows 

 larger. ^^ Is a house-ffy a true insect? What is the tech?iical 

 def?iition of an insect? 



Insects are full adult size when they emerge from the pupa, 

 the wings only growing and expanding during the first hour. 

 An insect is an invertebrate animal of the sub-king-dom Arthro- 

 poda. A typical insect has a distinct head, one pair of antennae, 

 3 pairs of legs, respiratory organs consisting of tracheae, and pass 

 through 4 stages of development, viz : Egg, larva, pupa, and 

 imago. 



107. Is petroleum ever found under granite? 



It is not probable that petroleum, a product of the carbonifer- 

 ous age, would be found normally under a primitive rock like 

 granite. 



108. What is the office of the wart fou7id 07i the fore legs 

 of the horse? 



Its use is unknown. 



