SOME METHODS FOR LOWER ANIMALS. 481 



at the same time an assistant injects 90 per cent, alcohol 

 through the anus. 



VOGT and YUNG (Anat. Comp. Prat., p. 641) say that 

 Cucumaria Planci (C. doliolum, Marenzeller) is free from 

 the vice of expelling its intestines under irritation ; but they 

 recommend that it be killed with fresh water, or by slow 

 intoxication with alcohol, chromic acid, or sublimate added 

 to the sea water in which it is contained. 



Synapta may be allowed to die in a mixture of equal 

 parts of sea water and ether or chloroform (S. Lo BIANCO). 



Holothurids, Dr. WEBER informs me, are admirably pre- 

 served in formaldehyde ; a weak solution is sufficient. 



GERAULD (Bull. Mas. Harvard Coll., xxix, 1896, p. 125 ; 

 Journ. Roy. Mic. Soc., 1896, p. 476) paralyses Caudina with 

 sulphate of magnesia, 21, and fixes with liquid of Perenyi 

 (or sublimate for the ovaries). He demonstrates cell-limits 

 by rinsing' epithelia with distilled water and impregnating 

 with 1 per cent, silver nitrate. 



HEROCJARD (Arch. Zool. Exp<'r., vii, 1899, p. 537) kills 

 Cucumaria by plunging into a 1 per cent, solution of chloral 

 hydrate warmed to 40 C., the anus being closed by means 

 of forceps. 



For tlie staining of muscles with methylen blue see IWANZOFF, Arch.f. 

 mik. Anat., xlix, 1897, p. 103. 



861. Asteroidea. HAM ANN (Beitr. z. Hist. d. Echinodermen, 

 ii, 1885, p. 2) finds it best to inject the living animal with a 

 fixing liquid. The cannula should be introduced under the 

 integument at the extremity of a ray, and the liquid injected 

 into the body-cavity. The ambulacral feet and the branchige 

 are soon distended by the fluid, and as soon as it seems to 

 have penetrated sufficiently the animal is thrown into a 

 quantity of the same reagent. 



In order to study the eyes, with the pigment preserved in 

 situ, they should be removed by dissection, should be 

 hardened in a mixture of equal parts of 1 per cent, osmic 

 acid and 1 per cent, acetic acid, and sectioned in a glycerin 

 gum mass, or some other mass that does not necessitate 

 treatment with alcohol (which dissolves out the pigment, 

 leaving the pigniented cells perfectly hyaline). For mace- 



31 



