FIXATION OF MOLLUSCA. 435 



course you will have taken care to select of as small a size as 

 possible). Take them out of the acid with your fingers (or in 

 some manner that may dispense with the employment of steel 

 instruments, which would blacken the tissues) and bring them 

 into 50 per cent, alcohol. Wash them thoroughly in that, and 

 then bring them in the usual way through successively stronger 

 alcohols. 



I most strongly recommend this process, which gives 

 admirably preserved preparations quite free from any opacity 

 either in the tissues or the tunic. The acid will not hurt the 

 fingers if they be washed immediately. 



S. Lo BIANCO recommends for this group the chloral 

 hydrate process, followed by fixation with sublimate or 

 chromo-acetic acid. 



Small pelagic Tunicates are very easily fixed with osmic 

 acid or acid sublimate solution, with the exception of An- 

 chinia. The not very numerous preparations I have made of 

 this exceedingly delicate form have all been unsatisfactory. 

 And some other similar forms may be found difficult. I have 

 had a striking failure with Salpa virgula, which I fixed with 

 rr Hemming/' and got a very poor preparation. The very 

 similar S. pinnata is fixed perfectly in this medium. 



Molluscoida. 



812. Bryozoa. For some methods of killing and fixing see 

 7, 14, and 15. S. Lo BIANCO employs for Pedicellina 

 and Loxosoma the chloral hydrate method, fixing with sub- 

 limate. For Flustra, Cellepora, Bugula, Zoobothrium, he 

 employs the alcohol method of EISIG, 12. 



BROCHER'S monobromated camphor, last section, may be 

 useful for this group. 



Mollusca. 



813. Fixation of Mollusca. Two groups at least amongst 

 the Mollusca offer considerable difficulties in the way of 

 fixation Lamellibranchiata and Gastropoda. 



If it be attempted to take living and normal Lamellibran- 

 chiata from the water they are contained in, in order to throw 

 them into a fixing solution, they invariably withdraw their 

 siphon and foot, shut their valves, and die in a state of con- 

 traction. And if it be attempted to open the shell by force 



