Diazona violacea should remain twelve hours in chloral 

 hydrate of 0.2 of 1 per cent, and then the killing and the hard- 

 ening should be done as with the Botryllidae, except that the 

 individual animal should be injected with the liquid. Small 

 colonies may be killed in acetic acid and hardened in one-half 

 per cent chromic acid. 



Leptoclinum and other forms of a certain consistency 

 are transferred from the chloral directly to the alcohol. 



Pyrosoma is suspended by a thread in the mixture of 

 alcohol and hydrochloric acid in a cylindrical jar, and, after 

 a quarter of an hour, is transferred to 60 per cent alcohol and 

 gradually to that which is stronger. Good preparations have 

 been made by putting the colony directly into 50 per cent alcohol. 

 Care must be exercised to get rid of the minute air bubbles which 

 are apt to form on the surface of the colony, though they usually 

 disappear of themselves. 



The Salpidae include animals of very various consistency, 

 from slimy to cartilaginous. Certain species, furthermore, al- 

 though they have consistency when young, become soft in the adult 

 stages and difficult to preserve. Sometimes the Salpas when 

 immersed in the fixing fluid contract greatly, closing the orifices 

 and dying in this condition. This may be remedied by introducing 

 a closed glass tube into one of the openings, which, by allowing 

 the entrance of the liquid, causes the animal to resume its natural 

 shape . 



The species with a hard body (Salpa bicaudata when soli- 

 tary and young; S. tilesi, both chain and solitary forms; S. zonaria 

 both chain and solitary forms) , are immersed in a mixture of fresh 

 water (100 c.c.) and concentrated acetic acid (10 c.c.) where they 

 remain for fifteen minutes. Then they are washed in fresh water 

 for ten minutes, and then transferred gradually to alcohol, where 

 it is necessary to float the larger forms by means of pieces of 

 cork attached to them with threads so that the gelatinous sac 

 shall not flatten down upon the intestinal nucleus within. When 

 treated in this manner, the animals remain very transparent, 

 crystals of marine salts forming in the tissues much less than 

 with the other liquids. 



The forms of medium consistency (young chains and solitary 

 individuals of Salpa maxima and S. pinnata, young chains of 

 S. bicaudata, both the adult forms of S. fusiformis and S. demo- 

 cratica-mucronata) are placed in the chrom-acetic mixture No. 1 

 for ten minutes and then put directly into weak alcohol. 



The very soft forms (large chains of Salpa bicaudata and 

 S. punctata, both forms of S. maxima, S. pinnata, and S. virgola) 

 are immersed in the chrom-osmic mixture for from fifteen to sixty 

 minutes, according to their size. Then they are washed in fresh 

 water and transferred to weak alcohol. 



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