ANIMALS WHICH LIVE ON OR WITHIN GROUSE 199 



X. Davainea cesticillus (Molin), 1858. 

 (The Stumpy Tapeworm of the Grouse.) 



A second much smaller form of tapeworm also belonging to the genus 

 Davainea has only been recorded twice in the course of the investiga- 

 tions of the Committee. Once a few specimens were taken from the 

 duodenum of a Grouse shot in Roxburghshire ; and it again was found 

 loose either "in the small intestine or rectum" of a Grouse from 

 Caithness. In both cases only young, immature specimens were met 

 with. It is remarkable for its short, stout, stiff appearance, and 

 for its small number of segments. 



This tapeworm, common in chickens and turkeys, is only an 

 occasional parasite of the Grouse, and in no case has its presence been 

 associated with any lesions or ulcerations of the intestinal wall. As a 

 factor in " Grouse Disease " it may be neglected. Its second host is 

 probably some Coleopteran (beetle) or Lepidopteran (butterfly or 

 moth), but at present this has not been proved. 



XI. Hymenolepis microps (Diesing), 1850. 

 (The Transparent Tapeworm of the Grouse.) 



Specimens of a second genus and a third species of cestode inhabit 

 the intestine of the Grouse. The same worm has been described from 

 the capercailzie, and from the blackcock. The living specimens of this 

 tapeworm have been found only in that part of the intestine known 

 as the duodenum, but after the Grouse is dead they may wander into 

 other parts. 



It is an extremely delicate, transparent tapeworm which exists 

 in almost countless numbers in the duodenum of the Grouse. On 

 cutting open this part of the alimentary canal of a Grouse infested with 

 these worms and it is seldom that a bird is found free from them 

 except in the winter months they are not at first apparent. They 

 are so fine and so transparent that they are invisible when alive, 

 and the contents of this part of the alimentary canal appear very 

 much like a thick soup. If we add some fixing agent such as corrosive 

 sublimate this soup resolves itself into a mass of very fine, delicate, 

 white threads inextricably tangled up together, and so numerous that 

 there seems but little room left in the duodenum for the passage of the 

 food. If, with great care for they break at the slightest strain we 

 succeed in disentangling one of these worms we shall find its head 

 embedded to a greater or less extent in the mucous lining of the 

 duodenum, into which, to use a poetic phrase, " it nuzzles " whilst 

 the body of the worm floats freely in the fluid contents of this part 

 of the alimentary canal. If we also succeed in freeing the head we 

 now have a complete worm, and can study its structure. (See Fig. 17.) 



We have no information about the fate of the eggs and embryos of 



