450 SOME ZOOLOGICAL METHODS. 



metres on to the water. The animals will be found suffi- 

 ciently narcotised for fixation in from four to eight hours. 

 For OpheliaddB he also employs 0*1 per cent, of chloral hydrate 

 in sea water. 



Many marine Chaetopoda may be successfully narcotised 

 (S, Lo BIANCO) in sea water containing 5 per cent, of alcohol, 

 or by means of the mixture, 12. 



The Polychseta sedentaria offer the difficulty of a complex 

 and very contractile branchial apparatus. They may some- 

 times be satisfactorily fixed by bringing them rapidly into 

 corrosive sublimate. Cold, not hot solutions should be taken, 

 as heat frequently shrivels up the branchiae. The species of 

 Polychseta errantia that offer a contractile branchial appara- 

 tus, as Eunice and Onuphis, may be treated in the same way. 



S. Lo BIANCO advises killing Chastopteridae, Sternaspidae, 

 Spirographis, Protula, by putting them for half an hour into 

 1 per cent, chromic acid. I have satisfied myself that good 

 show specimens can be obtained in this way ; but I doubt the 

 histological preservation of the parts being so good as with 

 sublimate specimens. Some of the sedentaria may be got 

 protruded from their tubes by leaving them for some hours in 

 Ol per cent, chloral hydrate in sea water (S. Lo BIANCO). 



See also the methods 14 to 19, and 811. 



I can recommend as a good fixing and hardening mixture 

 for Annelids in general the following fluid, due to EHLERS 

 (I do not know whether it has been published elsewhere) : 

 To 100 c.c. of chromic acid of 0'5 to 1 per cent, add from 1 to 

 5 drops of glacial acetic acid. The proportion of acetic acid 

 indicated is sufficient to counteract any tendency to shrinkage 

 due to the chromic acid. 



842. Blood-vessels of Annelids (KUKENTHAL, Zeit. f. wiss. 

 Mik., 1886, p. 61). The animals should be laid open and put 

 for two or three hours into aqua regia (4 parts of nitric acid 

 to 2 of hydrochloric acid) . The ramifications of the vessels 

 will then be found to be stained black, the rest of the 

 preparation yellow. 



843. Nerves of Annelids. The methylen-blue method and 

 the bichromate of silver method of Golgi (the rapid method). 

 For the latter see v. LENHOSSEK (Arch. f. mik. Anat., xxxix, 

 p. 102 ; Zeit.f. wiss. Mik., ix, 3, 1893, p. 342). 



