NERVE AND MUSCLE OF ARCTISCOIDA. 361 



For dissociation preparations, put the eye or the optic 

 nerve for twenty-four hours into 5 per cent, solution of chloral 

 hydrate, tease, and mount in glycerin. If the elements of the 

 teased tissues be fixed to the slide by means of Mayer's 

 albumen, they may be washed with alcohol and stained in situ, 

 or they may be depigmented before staining. 



718. Optic Ganglia (VIALLANES, Ann. Sci. Nat. ZooL, 1884, 

 4, and 1885, 4). Fix in a mixture of 1 volume of 1 per cent, 

 osmic acid and 2 volumes of 90 per cent, alcohol. After fixa- 

 tion, throw the tissues into absolute alcohol. After twenty- 

 four hours, stain with alum-carmine or Kleinenberg's hsema- 

 toxylin, make sections and mount them in balsam or glycerin. 



CUCCATI (Zeit. f. wiss. Zool., xlvi, 1888, p. 241) fixes the 

 brain of the blow-fly (Somomya erythrocephala) (after having 

 carefully incised the integuments of the head in several places) 

 for twenty -four hours in liquid of Flemming or RabPs mixture. 

 The object is imbedded in paraffin and sectioned in the usual 

 way. The sections are fixed to the slide with Mayer's albu- 

 men and there freed from the paraffin and carefully brought 

 through successive alcohols into water. They are then 

 stained for half an hour in a solution composed of 3 grammes 

 of Saurefuchsin, 1 of chloral hydrate, and 100 c.c. of water. 

 They are washed for ten minutes in water, rapidly dehydrated 

 with alcohol, cleared with clove oil and mounted in balsam. 



719. Nerve and Muscle of Arctiscoida (DOYERE, Arch. f. mik. 

 Anat.,1865, p. 105). A score or so of Milnesium tardigradum 

 are collected (it is well to have a large number, as the process 

 by no means succeeds with all individuals) and put into a 

 test-tube with water that has been deprived of its air by 

 boiling. A drop of oil is run on to the surface of the water, 

 so as thoroughly to exclude the air. After twenty-four to 

 forty-eight hours the animals will be found, not dead, but 

 fixed and extended in a cataleptic state ; the circulation of the 

 perivisceral fluid has ceased, the pigment of the cuticle has 

 disappeared or collected into patches that are no hindrance to 

 observation, the entire animal has gained in transparency, and 

 the nervous and muscular systems stand boldly out. The 

 animals are examined in boiled water, unless it be wished to 

 study the phenomena of resuscitation, in which case spring- 

 water should be used, 



