CHAPTER XXXIV. 



SOME METHODS FOB LOWER ANIMALS. 



823. Introduction. The following methods are all of them 

 such as give results applicable to histological study, and no 

 account has been taken of such methods as are merely useful 

 for the preparation of organisms for museum specimens or 

 for coarse dissection. 



On p. 74 will be found a note of warning as to the employment of the 

 now fashionable formaldehyde as a preservative. 



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 SALTATOBE Lo BIANCO in Mitth. Zool. Stat. Neapel, ix, 

 1890, p. 435. References to the work of S. Lo BIAXCO 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. Mik., viii, 1, 1891, p. 54. 



Tunica ta. 



824. Fixation of Tunicata. A method of SALVATOKE Lo 

 BJAXCO for killing simple Ascidians in an extended state has 

 been given above, 22. In the paper quoted above this 

 plan is recommended for Ciona, Ascidia, and Rhopalea. But 

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

 Molgula, Cynthia, etc., should first be narcotised by treat- 

 ment for from three to twelve hours with chloral hydrate 

 (1 : 1000 in sea water), then killed in a mixture containing 

 chromic acid of 1 per cent. 10 parts, acetic acid 10U parts, 

 and finally hardened in 1 per cent, chromic acid. 



The compound Ascidians with contractile zooids are diffi- 

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

 The best process known to me is the following (due to VAN 



