14 MATERIALS AND PROCESSES OF SLIDE-MAKING 



This is used in exactly the same way as the solution of Haug, but one must, 

 of course, be careful not to handle the object with steel implements because the 

 mercuric chloride will destroy them. 



No really satisfactory method for softening chitinous materials has yet been 

 discovered, though the following is much better than anything else: 



Jurray's Mixture: 



Chloral hydrate 50 Gm. 

 Phenol 50 Gm. 



Insects or other chitinous forms are fixed in the fluid of Carnoy and Lebrun 

 and are transferred without washing to Jurray's mixture, where they remain 

 from 12 to 24 hours. Then this mixture is washed out in chloroform, and the 

 objects are embedded in paraffin. 



Narcotization. There are many small invertebrates which cannot be made 

 satisfactorily into microscope slides after the process of simple fixation. These 

 forms, such as the majority of small hydroids and worms, are contractile, so 

 that it is necessary to narcotize them before fixation if they are to resemble 

 the living form after mounting. The whole subject of narcotization is very 

 difficult, for it requires great skill to add slowly small quantities of the se- 

 lected narcotic and then to fix the object at the exact moment that it is com- 

 pletely narcotized but before it is dead. Many marine forms, particularly sea 

 anemones, may be narcotized by adding small quantities of a saturated solu- 

 tion of magnesium sulfate to the water in which they are expanded. There are, 

 however, two mixtures which can be recommended for general purposes. The 

 first of these is: 



Hanley's Solution: 



Water 90 ml. 



Ethyl cellosolve 10 ml. 



Benzamine hydrochloride 0.3 Gm. 



This is an excellent narcotic for small and delicate forms, such as Rotifers 

 and Bryozoa. About one drop per 10 ml. should be added and well mixed 

 with the water in which the creatures are living. After about 10 minutes, fiir- 

 ther quantities may be added and left until narcotization is complete. 



A useful narcotic for less delicate forms is: 



Gray's Mixture: 

 Grind 48 Gm. of menthol in a mortar with 52 Gm. of chloral hydrate. 



This mutual solution of menthol and chloral hydrate is lighter than water. 

 A few drops placed on the surface of the water containing the specimen dis- 

 solves slowly, allowing both constituents to act rapidly and safely. This reagent 

 is recommended for Coelenterates of all kinds. 



