.z-^i Instructions for Collecting 



Worms. 



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INTKODUCTOEY EEMAEKS. 



On Collecting. 



The term " Worms," as here used, embraces a great many animals 

 which bear very Kttle resemblance to the popular conception of a 

 worm. Some little idea of their variety and of the situations in 

 which they are most likely to be found may be gathered from the 

 lists given below. 



It will be seen that the parasitic groups are A 2 and 3, C, D, E, 

 and those mentioned on pp. 10-11. 



The majority are internal parasites of vertebrate animals ; 

 but their position in their hosts varies very greatly. Manj^ 

 live in the alimentary canal, but many occur in other cavities and 

 organs of the body, e.g. the heart, liver, lungs, kidneys, bladder, 

 body-cavity, nasal cavities, or even in the blood-vessels, bronchial 

 tubes, and among the muscles and connective tissue. Some of the 

 Trematodes and Leeches are external parasites of fishes and oiher 

 aquatic or amphibious animals, and may be found attached to their 

 skin, especially on the fins, or on the gills and in the cavity of the 

 mouth. Hence one must not be content merely to open the 

 intestines of an animal and make a hasty examination there, but all 

 parts of the animal ought to be inspected. Even the connective 

 tissue between the skin and flesh often contains parasites. Filariae 

 (Nematodes), for instance, often choose this situation, where they 

 lie coiled up in capsules or "cysts"; and the larval forms of 

 various other parasites may be discovered in similar positions. 

 When found in the connective tissue or in the peritoneum covering 

 the internal organs and body-cavity, or in the walls of the stomach, 

 etc., it is advisable to cut out and preserve the cyst with a small 

 portion of the surrounding tissue. 



It is worth wiiile to collect all parasites seen, since it is often 

 only the most careful microscopic investigation that can determine 

 a species. 



Some small Nematodes parasitic in the intestines, more 

 especially of birds, are so fine that they are difficult to see unless 

 some of the contents of the intestine or cgeca are shaken up in salt 

 solution or water, when the little hair-like creatures can be picked 

 up with a needle, to which they adhei-e readily. For many 



