476 CHAPTER XXXIV. 



the moment of using. Canada balsam, curiously enough, is said to some- 

 times make Nematodes opaque. 



Demonstration of living Trichinae (Barnes, Amer. Mon. Mic. Journ., 

 xiv, 1893. p. 104; Journ. Boy. Mic. Soc., 1893, p. 406). A piece of 

 trichinised muscle of the size of a pea should be placed in a bottle in a 

 mixture of 3 gr. of pepsin, 2 dr. of water, and 2 minims of hydrochloric 

 acid. The whole should be kept at body temperature for about three hours 

 with occasional shaking. The flesh and cysts being dissolved, the fluid is 

 poured into a conical glass, and allowed to settle ; the trichinae are drawn 

 off from the bottom with a pipette, got on to a slide with water, and exa- 

 mined on a hot stage. 



GRAHAM (Arch. mik. Anat., 1, 1897, p. 216) isolates Trichinae by mace- 

 rating for one or two days in 2 per cent, acetic acid, staining with aceto- 

 carmine, and teasing. 



856. Nemertina. After considerable experience of this 

 difficult group I have to say that I know of no method of 

 fixation that will certainly give good results. My best 

 results have always been obtained with cold saturated 

 sublimate solution, acidified with acetic acid. I have tried 

 most of the other usual fixing agents, such as the osmic and 

 chromic mixtures, and do not recommend them for this 

 group, for they seem (the chromic mixtures and perchloride 

 of iron in particular) to act as irritants, and provoke such 

 violent muscular contractions that the whole of the tissues 

 are crushed out of shape by them. And, besides, they do 

 not kill as quickly as sublimate. 



I have found it a good plan to decapitate the animals (in 

 the larger forms), cut them up quickly into lengths (not too 

 long), and throw these sharply into the sublimate, the 

 muscular contractions being less energetic in segments that 

 are no longer in connection with the cerebral ganglia. 



Perhaps a better method than this will be found in the 

 simple process, suggested to me by Prof. DU PLESSIS, of fixing 

 with hot (almost boiling) water. On the few occasions on 

 which I have tried it the animals have died in extension, 

 without vomiting their pi-oboscis ; and I think it is certainly 

 worth trial, especially for the larger forms. 



I have tried FOETTINGER'S chloral hydrate method ( 18). 

 My specimens died fairly extended, but vomited their pro- 

 boscides. According to S. Lo BIANCO (loc. cit., p. 461) 

 narcotisation with a solution of O'l to 0'2 per cent, in sea 

 water for six to twelve hours is useful. 



