SOME METHODS FOB LOWER ANIMALS. 



ammonia, which facilitates dissection (VoGT and YUNG, Traite 

 d'Anat. Comp., ii, p. 203). 



842. Arctiscoida (DOYERE, Arch. f. mik. Anat., 1865, p. 105). Exa- 

 mination of living animals after partial asphyxiation in boiled water. See 

 previous editions. 



843. BETHE'S Stain for Chitin (Zool. Jahrb., Abth. f. Anat., 

 viii, 1895, p. 544; Zeit. f. wiss. Mik., xii, 4, 1896, p. 498). 

 Desirous of staining the chitinous hairs and plates of the 

 otocyst of Mysis, BETHE found advantage in employing a 

 process in which anilin black is produced on the tissue itself. 

 Anilin black is a product of the oxidation of anilin hydro- 

 chloride. BETHE proceeds as follows : Series of sections 

 mounted on a slide are put for three or four minutes into a 

 freshly prepared 10 per cent, solution of anilin hydrochloride, 

 to which has been added one drop of hydrochloric acid for 

 every 10 c.c. They are then rinsed in water, and the slide 

 is put with the sections downwards into 10 per cent, solution 

 of bichromate of potash. The stain quickly begins to show 

 itself, but is at first in general not sufficiently intense. The 

 process is then repeated until the desired intensity of stain 

 is obtained, care being taken to rinse the sections well with 

 water after each of the operations, in order to avoid the 

 formation of precipitates. The stain is at first green, but 

 becomes blue in tap water or alcohol containing ammonia. 



The same paper contains a hint concerning the preparation 

 of telsons for section-cutting. They are put for eight to 

 fourteen days into 40 per cent, alcohol, to which nitric acid 

 is gradually added, so that by the end of that time they 

 have been brought into alcohol containing 20 per cent, of the 

 acid. This softens the chitin, and somewhat breaks down 

 the structure of the otolith, so that good sections through it 

 are occasionally obtained. 



Vermes. 



844. Enteropneusta. Lo BIANCO (op. cit.,p. 460) fixes with 

 picro-sulphuric acid or 0'5 per cent, chromic acid, with 

 previous narcotisation with alcohol if desired. 



845. Myzostoma. WHEELER (Mitth. Zool. Stat. Neapel, xii, 



