598 IN VERTEBRA TES 



methyl benzoate celloidin method of Peterfi, § 177. The main 

 point is that the diaphanol softens chitin, and in the subsequent 

 treatment of the specimens it is necessary to avoid too much 

 heat. In using the diaphanol method it is necessary to see that 

 the liquid is freshly bought, or that it has been kept in a cool 

 dark place, otherwise it does not work. 



Diaj)hanol is a trade name for a mixed substance produced by 

 passing the vapours of chlorine dioxide (ClOo) into ice cold 50 

 per cent, acetic acid. It is not advisable to try and make diaphanol 

 in a biological laboratory. It is obtainable from Messrs. Leit/., 

 who supply a leaflet. 



(Refer also to E. Schmidt and E. Graumann, Ber. deutsch. 

 chem. Ges., liv, 1860 ; P. Schulze, Sitz. Ges. nat. Freunde, Hefte 

 8/10, 1921, and Biol. Central, 1922 ; F. Duysen, Ber. deutsch. 

 hotan. Ges., xcii, 1922 ; R. Potonie, Die Braunkohle, 1922.) 



1185. List {Zeit. wiss. Mik., 1886, p. 212) treats Coceidae (after 

 hardening) for eighteen to twenty-four hours with eon de Javelle, diluted 

 with 4 volumes of water. After washing out they may be imbedded 

 in paraffin, and good sections obtained. 



Saling (Dissert. Marburg., 1906, p. 11) boils larvae of Tenebrio for 

 some minutes in eati de Labarraque, the heat serving to fix the soft parts, 

 which in successful cases are well preserved. Wash out with warm 

 water, then alcohol. 



Sazepin's method for antennae of Chilognatha (Mem. Acad. Imp. St. 

 Petersb., xxxii, 1884, pp. 11, 12) consists in steeping antennae (that have 

 been dehydrated with alcohol) for twenty-four hours in chloroform 

 containing a drop of fuming nitric acid (shake occasionally). 



Betiie (Zool. Jahrb., viii, 1895, p. 544) puts telsons of My sis for eight 

 to fourteen days into 40 per cent, alcohol, to which nitric acid is gradu- 

 ally added, so that by the end of that time they have been brought into 

 alcohol containing 20 per cent, of the acid. This softens the chitin, and 

 somewhat breaks down the structure of the otolith, so that good 

 sections through it are occasionally obtained. 



Similarly Herbst, Arch. Etitivickelungsmech., ix, 1899, p. 291. 



See also the depigmentation processes, §§ 611 to 620. 



1186. Double Imbedding of Insects. A. E. Boycott dissolves 

 1-5 grm. desiccated celloidin chips in 50 c.c. clove oil, or, better, 

 adds the celloidin in an ordinary ether-alcohol solution and 

 evaporates off the solvent in the oven overnight. 



It takes many days to dissolve thoroughly, but the time may 

 be shortened by keeping it at 90° F. Fix objects in absolute 

 alcohol ; bring them into clove oil, and allow this to clear the 

 preparations, then transfer to the clove oil celloidin. The time 

 in this must be gauged according to the size and nature of the 

 insect ; fleas, if a rupture is made in the chitinous covering, are 

 penetrated in twenty-four hours or less. When ready to imbed, 

 dip a cover-glass in melted paraffin wax, to get a smooth surface 

 on which the celloidin solution will not spread, but forms a thick 

 drop. Place the insect on the prepared glass slip in a drop 



