BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [30] 



margins of the objects, not being able to penetrate well between the 

 two plates. In this manner well distended, flat preparations have been 

 made of Tristomum, Acantliocotyle, Distomum, Calicotyle, and of many 

 other Distomata and Polystomata. 



BhahdoGoelia and Dendroccelia. — When they are not quite thoroughly 

 distended in a little water they are killed with boiling saturated subli- 

 mate and at once poured into a larger receptacle containing fresh water, 

 where liquid and animals are allowed to cool. From this mixture they 

 are transferred to fresh water, and after a few minutes to alcohol. For 

 certain Polyclades (JEurylepta, Pseudoceros) it is necessary that the sub- 

 limate be warmed a little again, otherwise the bodies break up. 



Miiller's larvse may be killed with saturated sublimate, either cold 

 or hot. 



Nemertinw. — Great difficulty has been encountered in dealing with 

 the nemertine worms, because before they are comj)etely distended 

 they contract again, twisting the body badly and breaking to pieces. 

 For some time the eftbrt was made to narcotize the different species by 

 dropping alcohol little by little into the sea water containing the ani- 

 mals, so that as the two mixed the animal would gradually lose sensi- 

 tiveness and would die. Although this operation was performed with 

 the greatest care, and the worms showed no signs whatever of life, 

 when transferred to the fixing liquid they contracted and became dis 

 torted. If the method just described be used with large specimens of 

 Cerehratulus niarginatus, one can not tell whether the animals are 

 entirely dead or not. Good success, however, has been attained by 

 rapidly plunging them head first into a mixture consisting of Muller's 

 solution ^ 7 parts and concentrated hydrochloric acid 1 part. After a 

 few minutes wash the animals and harden them in alcohol in a wax- 

 bottomed tray. 



After relocated experiments the Nemertines were at last successfully 

 narcotized in a solution of chloral hydrate in sea water of 0.1 of 1 per 

 cent strength, where they were allowed to remain from six to twelve 

 hours and then hardened in alcohol in the long zinc box with wax in 

 the bottom. When these animals have been narcotized for not too long 

 a time in the chloral hydrate they will fully regain vitality and power 

 of movement after a little if placed again in sea water. 



By this method good j)]eparations can be made of the genera Cari- 

 nella, Gerebratulus, Drepanopliorus, Nemertes, Folia, etc., in a state of 

 perfect distention and with the proboscis protruded. The more resist- 

 ant forms [Langia, Amphi])orus, and also Brepanophorns) , after they have 

 been narcotized in a 0.1 of 1 per cent solution, may well be placed for 

 some hours in a 0.2 of 1 per cent solution before they are killed. 



The larval form, Filidnim, is killed either with the sulphate of copper 

 and sublimate mixture or with saturated sublimate alone. 



' Potassium Ibichromate, 2 grams ; sodium sulphate, 1 gram ; distilled water, 100 

 n-ams. 



