that the bell does not touch the bottom of the jar and let the 

 animal remain thus only until completely hardened. 



Cotylorhiza tuberculata (Cassiopeia). — Formalin of from 

 to 3 per cent may be used to good advantage for killing and harden- 

 ing this species. Another method is to treat with osmic acid, as 

 was done with Rhizostoma, but when the brown tint begins to appear, 

 a 5 per cent solution of bichromate of potassium should be substi- 

 tuted for the osmic acid and should be renewed after a few days. 

 The animal ought to remain in this reagent for about two weeks, 

 but it can not remain much longer than that without suffering in- 

 jury. Then remove the object to 35 per cent alcohol. Numerous 

 crystals of a salt are formed on the outside of the animal and 

 a heavy precipitate falls to the bottom of the receptacle, making 

 it necessary to change the alcohol frequently and to add a few 

 drops of concentrated sulphuric acid thereto. 



The larval forms of the Acalephs (Scyphistoma, Strobila) 

 are killed with hot saturated sublimate. Strobila is also well 

 fixed with a mixture consisting of 9 parts of concentrated acetic 

 acid and 1 part of osmic acid of 1 per cent. From this it is 

 quickly transferred to fresh water for washing and put into alcohol. 



Siphonophora 



As with the Hydromedusae, the preparation of the Siphono- 

 phora should be accomplished as soon as possible after capture, 

 and only those specimens should be treated which are in good liv- 

 ing condition. Particularly with the Physophoridae is it true 

 that the whole colony will go to pieces if it remains for a few 

 hours in the same receptacle in which the water has had a sudden 

 change of temperature, though frequently the breaking up does 

 not take place until the colony comes in contact with the fixing 

 fluid. Much care must also be exercised not to shake roughly 

 the vessel which contains the animals before they have been killed. 

 It has often been observed that a trace of an acid or other reagent 

 in the water is enough to destroy the colony. The receiving vessel 

 must be perfectly clean. 



Athorybia rosacea, the single representative of the family 

 of Athorybiadae, which is found in the Bay of Naples, is very rare, 

 and but one specimen has been prepared at the station. That was 

 killed with the mixture of sulphate of copper and sublimate. The 

 colony contracted somewhat, but remained entire. It was washed 

 with fresh water and then placed in alcohol. 



The very delicate species (Physophoridae, Agalmidae) must 

 be transferred from the jar in which they were captured to the 

 crystallizing dish in which they are to be killed by immersing 

 both vessels in a tank of water and cautiously pouring the animals 

 over. Leave water enough in the crystallizing dish to give the 



- 30 - 



