H. A. Baylis 
403 
the subcutaneous connective tissue and muscles; in fishes and in certain 
amphibia and reptiles, the outer surface of the skin; and in fishes the swim- 
bladder and gill-cavities. 
It must also be borne in mind that while most of the “intestinal” parasites 
are found lying freely in the lumen of the stomach or intestines, or merely 
attached to their walls, some also burrow in the mucous membrane or in and 
between the muscular coats, and inhabit galleries or tumours formed in these 
situations. In birds, certain groups of nematodes occur between the coats 
of the gizzard, which should be stripped apart during the dissection. 
To search for intestinal parasites the gut of the host should be slit up with 
scissors (preferably blunt-ended or enterotome), and after the removal of the 
gross contents and any obvious parasites, the mucous membrane should be 
washed with normal salt solution or water, and carefully examined for the 
less conspicuous forms that may be adhering to it. 
In the case of small animals, the whole of the gut may sometimes be 
opened under water in a dish, or opened and then shaken up in a jar, and the 
entire contents thus washed out. This last method has the disadvantage that 
it is sometimes impossible to say from what region of the gut the parasites 
came. 
Many small worms, especially such forms as the nematodes of the Tricho- 
strongyle group, are not easily detected unless the contents of the part of 
the intestine under examination ( e.g . the caeca of a bird) are scraped out and 
shaken up in the washing fluid. A good plan in such cases is to scrape off the 
matter adhering to the mucous membrane with an instrument such as the 
back of a knife, and stir and shake it up in a tall jar of the fluid. On allowing 
this to stand for a few minutes, the worms will sink to the bottom, and most 
of the dirty fluid may be decanted off. Clean fluid is then added, and the 
process is repeated until the worms are comparatively free from other matter. 
The jar is then emptied into a flat dish, and very small specimens may be 
picked up on a needle, to which they will readily adhere, or if necessary with 
a pipette, under a lens or dissecting microscope. 
“Prospecting” for such worms as Trichostrongyles may sometimes be 
carried out to advantage by a very simple method. This consists in placing 
a small quantity of the material scraped from the mucous membrane on a 
glass slide, and then placing another slide on the top of it, and exerting just 
enough pressure to spread the material out into a thin layer, in which the 
worms can easily be seen, if present, either with the unaided eye or under a 
low magnification. 
r • • 
In collecting cestodes gentle treatment is necessary, as they are often 
very fragile, and some care must be taken to avoid leaving their “heads” 
(scolices) adhering to the mucous membrane. In the case of small specimens 
the membrane should be gently scraped with the back of a scalpel, or some 
similar instrument. If the heads of comparatively large specimens are very 
firmly attached, gentle persuasion with a scalpel or needles in a dish of salt 
