16 Mr. Arthur E. ShipUij [Feb. ?>, 



year round, known to every sportsman, and a slender thread-worm 

 which inhabits the paired cteca or bhnd-guts, which are unusually 

 large in the grouse and play a very important part in its digestion. 

 The latter worm under certain conditions, and Avhen present in con- 

 siderable numljers, is associated with one of the two diseases which 

 have especially attracted the attention of the Inquiry. 



Davainea urogalli (Modeer). — Of the three tape-worms that are 

 found in the grouse, this species is by far the largest and by far the 

 most common. It exhibits little seasonal variation and is found in 

 considerable numl)ers all the year round. The birds become infected 

 at an early age. 



D. urogalli is normally found in the small intestine, though some- 

 times parts of it are found in other portions of the alimentary canal. 

 As a rule, three or four individuals are met Avith. At other times, 

 especially in weakly Ijirds, there are dozens, and these fill up the lumen 

 of the intestine to such an extent that it is difficult to see how food 

 can pass along. 



D. urogalli, like most cestodes, produces a very large number of 

 eggs at any one time. It may be, at a rough estimate, at least 100,000, 

 but this figure is no measure of the reproductivity of the cestode, 

 because as fast as new segments break off at one end new ones are 

 formed just behind the head, and the animal goes on producing new 

 segments very much in the same way as a recurring decimal repro- 

 duces ciphers. Hence the eggs of this cestode must be scattered in 

 countless milHons all over the grouse moors. They are probably 

 eaten by some insect or land mollusc and in the body of these inverte- 

 brates change into the cysticercus or larval stage. 



The popular notion that grouse do not eat animal food is entirely 

 wrong. For the first three weeks of the bird's life the greater part 

 of its diet consists of insects or arachnids, and from the crop of the 

 first grouse I ever dissected I took six saw-fly larvte, eight caterpillars 

 of a Geometrid moth, one caterpillar of a smaller moth, two small 

 Tineid moths and a number of Hemipterous insects resembling the 

 frog- or cuckoo-spit, a fly, two specimens of plant-lice, one small 

 spider, and the remains of four slugs. The gizzard of the same 

 animal contained, in a more Ijroken-up condition, two or three dozen 

 larva of saw-flies and moths, some young Hemipterous insects and 

 the pupa of two true flies. 



In searching for the larval or cysticercus stage of these and the 

 other cestodes, we have examined a considerable number of insects 

 which occur commonly on grouse moors. We have also carefully 

 searched the bodies of many fresh-water Crustacea which al)Ound in 

 the pools and tarns from which grouse drink, Irat hitherto our 

 searches have met with no success. One specimen of cestode which 

 infests the common fowl is said to have its second host in several 

 species of the slug Limax, but we have not succeeded in finding cysti 

 of either form of tape-worm in this slug. 



