METHOD OF PRESERVING SPECIMENS 103 



Langeron 1 uses lactophenol (2 parts glycerine, 1 part distilled 

 water, 1 part crystallized carbolic acid, and 1 part lactic acid). 

 The Nematodes are killed with diluted formol (5 : 100), and then 

 transferred to lactophenol which has been previously diluted with an 

 equal quantity of water, and in this they are allowed to remain for a 

 few hours. A large drop of lactophenol is dropped on to the middle 

 of the glass slide, the worms are placed in it and covered with a 

 cover-glass. The whole of the space under the cover-glass is then 

 filled with lactophenol ; the corners are cemented with a drop of 

 glycerine-gelatine (2 parts gelatine, 6 parts water, 7 parts glycerine), 

 the edges are painted with the same material, and, after the gelatine 

 has hardened, they are finished with a couple of coats of good 

 varnish. 



(4) Acanthocephales. Although they occur but rarely in man, the 

 study of Acanthocephales should not be neglected. Small species, suit- 

 able for whole preparations, are found in the intestine of fish, frogs, 

 water-birds and waders. As a general rule, they are firmly fixed in 

 the substance of the intestinal wall by means of hooks with which the 

 proboscis is covered, and are to be released only by very careful 

 measures. Other varieties do not penetrate beyond the mucosa, and 

 these are more easily freed. Occasionally the parasites are found free 

 with retracted probosces, either in the lumen of the bowel or against 

 the bowel-wall. Fresh specimens are generally flabby and fallen 

 together, and they are more or less wrinkled. When put into normal 

 saline they swell up, the skin becomes taut, and the proboscis is 

 frequently protruded. It is inadvisable, however, to wait until this 

 occurs. The parasities should be cleaned with a brush in normal 

 saline, and as soon as they begin to swell they should be laid upon a 

 glass slide, covered with a cover-glass, and gently pressed until the 

 proboscis is protruded. They are then fixed in strong alcohol which is 

 introduced under the cover-glass, while an even pressure is maintained 

 by placing pieces of lead upon the cover-glass ; or a small bottle of 

 mercury may be used ; occasionally it may be necessary to use a press. 

 The process of fixing occupies only a short time, and the specimens 

 are then cleared in glycerine and embedded in glycerine-gelatine in the 

 manner already described for the preservation of Nematodes. After 

 fixing, they should be transferred to watch-glasses and stained. If a 

 watery solution of the stain is employed, the worms are very liable to 

 swell up again. In that case they must again be pressed between 

 two glass slides, and treated with alcohol in stages of gradually increas- 

 ing strength. The specimens may be embedded in gelatine after 



1 Langeron, C. R. soc. bioL, Iviii, 1905, p. 749 ; Arch, de paras., xii, 1908, 

 p. 153. 



