APPENDIX. 465 



lamp-black mixed with it till it is quite black, and while it is 

 cooling small shot or other small pieces of metal dropped into it. 

 You thus get a smooth black surface as a background for dissection, 

 and one which will not float up when water is poured in. The 

 thickness of paraffin should be enough to allow plenty of room for 

 pins to be stuck into it, while leaving enough depth in the dish for 

 the animal to be entirely covered with water. The surface of the 

 paraffin will soon be damaged by the pins, but can be restored by 

 passing a Bunsen-flame over it a few times. 



If cork be used, a flat piece is needed, not less than 6 in. x 4 in., 

 and in. thick. This must be firmly attached to a flat piece of 

 lead of the same size. 



(J) A pickle- or other wide-mouthed jar to keep specimens in. 



(jfc) A microscope, with low- and high-power objectives (Leitz's 

 nos. 3 and 7). 



(Z) Glass slips (3 in. x 1 in.) and medium cover-glasses ( in. 

 diameter or square). 



(m) Bristles are useful as very fine seekers. They may very 

 conveniently be cut off the rabbit's " \vhiskers." 



THE ANIMAL TYPES. 



Rabbits can be got anywhere : the tame varieties will do 

 quite as well as the wild. They are most conveniently killed 

 by chloroform : take a small box, just large enough to hold 

 the rabbit, pour a spoonful of chloroform on a rag and 

 spread this out in the box so that it may evaporate quickly, 

 keeping the lid down ; after a minute or two, place the 

 rabbit in the box, put a weight on the lid, and wait two or 

 three minutes. 



Frogs may be found in spring and summer in abundance 

 in marshy places (brickfields, for example), or town-dwellers 

 can get them by post from Mr. T. Bolton, 25, Balsall Heath 

 Road, Birmingham, or from dealers in other large towns 

 who generally advertize in such periodicals as Nature, 

 Knowledge, Natural Science, Science Gossip, etc. Failing 

 frogs, toads will do quite well, except as regards the shoulder- 

 girdle (see chap, xiii., 21). Frogs may be killed in the 

 same way as rabbits, using a correspondingly smaller box 

 and quantity of chloroform. 



The Marine Biological Laboratory, Citadel Hill, Ply- 

 mouth, supply preserved Dogfish, Obelia, Nereis, and 

 other marine types ; "a list can be obtained from the 

 Director. '* 



ZOOL. 30 



