434 SOME ZOOLOGICAL METHODS. 



CHAPTER XXXII. 



SOME ZOOLOGICAL METHODS. 



Tunicata. 



811. Fixation of Tunicata. A method of SALVATOEE Lo BIANCO 

 for killing simple Ascidians in an extended state has been 

 given above, 18. In the paper quoted below* this plan is 

 recommended for Ciona, Ascidia, and Rhopalea. But many 

 other forms, such as Clavellina, Perophora, Phallusia, Molgula, 

 Cynthia, &c., should first be narcotised by treatment for from 

 three to twelve hours with chloral hydratef (1 : 1000 in sea 

 water), then killed in chromo-acetic acid (chromic acid of 1 

 per cent. 100 parts, acetic acid 10 parts). 



The compound Ascidians with contractile zooids are difficult 

 to manage if one does not go the right way to work. The 

 best process known to me is the following (due to VAN BEN- 

 EDEN, kindly communicated to me by Dr. C. Maurice). Place 

 the corms in clean sea water, and leave them alone for a few 

 hours, in order that the zooids may become fully extended. 

 Seize the corms with your fingers, and plunge them suddenly 

 into glacial acetic acid. Leave them there for two, four, or 

 six minutes, according to the size of the corms (which of 



* A valuable paper giving an account of a number of the processes 

 employed in the Naples Zoological Station for the preservation of marine 

 animals has been published by SALVATOBE Lo BIANCO in Mitth. zool. Stat. 

 Neapel, ix, 1890, p. 435. Keferences to the work of S. Lo BIANCO in the 

 remainder of this chapter are to that paper. An abstract of it is contained 

 in Amer. Natural, xxiv, 1890, p. 856, and Journ. Roy. Mic. Soc., 1891, 

 p. 133, and a very full account in Zeit.f. wiss. Mile., viii, 1, 1891, p. 54. 



f A new narcotising process recently incroduced by my friend Dr. 

 BBOCHEE, of Geneva, has been warmly recommended to me as being more 

 certain in its action than those hitherto employed. It consists in treatment 

 with monobromated camphor, which, in the case of small organisms at all 

 events, may be exhibited by simply placing a few crystals in the water in 

 which they are contained. 



