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, Acanthocotyle, Distomum, Calicotyle, and 

 of many other Distomata and Polys tomata. 



Rhabdocoelia and Dendrocoelia. — When they are not quite 

 thoroughly distended in a little water they are killed with boil- 

 ing saturated sublimate 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 (Eurylepta, 

 Pseudoceros) it is necessary that the sublimate be warmed a little 

 again, otherwise the bodies break up. 



Miiller's larvae may be killed with saturated sublimate, 

 either cold or hot. 



Nemertinae. — Great difficulty has been encountered in deal- 

 ing with the nemertine worms, because before they are completely 

 distended they contract again, twisting the body badly and break- 

 ing to pieces. For some time the effort was made to narcotize the 

 different species by dropping alcohol little by little into the 

 sea water containing the animals, so that as the two mixed the 

 animal would gradually lose sensitiveness 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 distorted. If the method just 

 described be used with large specimens of Cerebratulus marginatus, 

 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 repeated 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 preparations can be made of the genera 

 Carinella, Cerebratulus, Drepanophorus, Nemertes, Polia, etc., in 

 a state of perfect distention and with the proboscis protruded. 

 The more resistant forms (Langia, Amphiporus, and also Drepano- 



Potassium bichromate, 2 grams; sodium sulphate, 1 gram; distilled 

 water, 100 grams. 



- 37 - 



