366 SOME ZOOLOGICAL METHODS. 



acid attains this end, even after preliminary intoxication with 

 tobacco smoke or chloroform; the animal thus treated dying 

 contracted. 



SAEFFTIGEN (Morphol. Jahrb., x, 1884, p. 120; Journ. Roy. 

 Mic. Soc. (N.S.), v, 1885, p. 147) obtained the best results by 

 killing gradually with O'l per cent, osmic acid; the animals 

 placed in this contract during the first hours, but stretch out 

 again and die fully extended. 



Another method of killing is treatment with O'l per cent. 

 chromic acid ; Echinorhynci live for days in it, but eventually 

 die fully extended. 



731. Gephyrea. DE CASTELLAENAU (LaEst. Zool. deNapoles, 

 p. 137) says that Phascolosoma, Phoronis hippocrepis, Sipun- 

 culus nuduSj and 8. tesselatus should be killed and fixed with 

 chromic acid ; and Aspidosiphon Miilleri, Bonellia viridis, and 

 B. fuliginosa with picro-sulphuric acid. 



VOGT and YUNG (Anat. comp. prat., p. 373) direct that 

 Sipunculus uudus be kept for some days in perfectly clean 

 basins of sea water, in order that the intestine of the animals 

 may be got free from sand, which would be an obstacle to 

 section cutting, and then anaesthetised with chloroform, under 

 which treatment they die extended, and may be fixed as 

 desired. 



APEL (Zeit. f. wiss. Zool., xlii, 1885, p. 461) says that 

 Priapulus and Halicryptus can only be satisfactorily killed by 

 heat. The animals may either be put into a vessel with sea 

 water and be heated on a water-bath to 40 C. ; or they may 

 be thrown as rapidly as possible into boiling water, which 

 paralyses them so that they can be quickly cut open and 

 thrown into one third per cent, chromic acid, or picro-sulphuric 

 acid. 



732. Rotatoria. By far the most important method for the 

 study of this group consists in the observation of the living 

 animals. ( ireat difficulty exists in the way of getting them 

 t. keep sufficiently quiet. VOGT and YUNG (Anat comp. prof., 

 p. 420) say that a drop of solution of any of the soluble salts 

 of strychnin run under the cover sometimes renders service. 

 w "-/i. de /{/../., viii, iv, 1888, p. 713) finds that 



-n-yelmin, pru ic acid, and curare art. ton strong Iv ; of all 

 the reagents he tried, '1 percent, solution of hydrochlorate 



