colony free movement, and wait for the polyps and the nettle- 

 filaments to become well distended and naturally arranged before 

 going on with the treatment. 



Physophora, Agalma, Halistemma, and Forskalia are killed 

 with the mixture of sulphate of copper and sublimate in volume 

 equal to or double that of the water in the crystallizing dish 

 containing them. The mixture must be poured rapidly into the 

 dish and not directly onto the animal. After a few minutes, as 

 soon as dead, the colony should be transferred by means of a 

 large horn spatula to the hardening solution, which is not the 

 same for all the species. 



(a) Physophora, Agalma, and Halistemma are put directly 

 into 35 per cent alcohol, and after a few hours transferred to 

 that of 70 per cent. As soon as Physophora has been put into the 

 35 per cent alcohol, its nettle-filaments should be stretched out 

 as far as possible with a pair of light forceps before they become 

 rigid. To change the liquid in the swimming bell it is necessary 

 to make an injection with a pipette. Bubbles of air always form 

 in the bells, which, through their tendency to float, tend to 

 change the natural shape of the bells, or, raising the whole 

 colony, flatten it at the surface of the liquid. To get rid of 

 these bubbles it is necessary to compress the bells gently. 



(b) The genus Forskalia is transferred from the mixture 

 of copper sulphate and sublimate to Flemming's solution. The 

 animals remain in this from two to six hours, according to their 

 size, and are then washed in fresh water and transferred to weak 

 alcohol, and so on gradually. The hardening of large colonies 

 succeeds better in the mixture of bichromate of potassium and 

 osmic acid, where they can lie even twenty-four hours without 

 hardening too much. To free the animal from the crystals which 

 form in the tissues and render them opaque, a few drops of con- 

 centrated sulphuric acid should be added to the first alcohol 

 into which the colony is put. After that, pure alcohol may be 

 used. 



For the permanent preservation of the Physophoridae, after 

 they have remained for a few days in 70 per cent alcohol in 

 crystallizing dishes for hardening, they are to be put into tubes, 

 arranging them so that the anterior end of the colony is toward 

 the mouth of the tube, by immersing the tube in the liquid and 

 gently working the colony into it. Small specimens of Agalma 

 and Halistemma can be taken by the posterior end with small forceps 

 and gently forced into a tube filled with 70 per cent alcohol so 

 that the bells point toward the opening. The tube should be small 



Chromic acid of 1 per cent, 25 c.c; osmic acid of 1 per cent, 

 10 c.c; glacial acetic acid, 5 c.c, and distilled water, 60 c.c. 



- 31 - 



