270 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



2, The best and most complete life history of Strong ylus pergravilis (Cob.), supposed 

 to produce the grouse disease. 



No life history would be considered satisfactory unless the different stages of de- 

 velopment were observed and recorded; the competition was open to naturalists of 

 all nationalities. Essays in English, German, or French were to be sent to the sec- 

 retary of the society on or before October 15, 188$. 



Although birds only are concerned in this matter, it is obvious that 

 tbe economic interest involved in a solution of the questions con- 

 cerning the gapes is sufficiently great. The scientific interest is no less 

 so, because there are to be determined not only the zoological position of 

 the worm under consideration, and its role in the terrible disease which 

 destroys the gallinaeeans, both domestic and wild, but also its mode of 

 reproduction, a point hitherto entirely unknown. 



This is the subject of the present memoir, a memoir in which I be- 

 lieve I have cleared np all the pending questions upon the zoological 

 position of the red- worm, on its anatomy and physiology, on its role ;is 

 a cause of the gapes, finally on its embryogeny and metamorphosis, 

 and consequently upon its mode of propagation, and upon the best 

 means of preventing its multiplication and arresting its ravages. 



HISTORICAL. 



The first mention of this disease was made by Dr. Wiesenthal, who 

 observed it in 1799, at Baltimore, Md,, among hens and turkeys.! In 

 1800, 1807, and 1809, Georges Montagu J saw this epizootic among chick- 

 ens in England. He believed that of all the birds of the poultry yard 

 only the hen could be its victim, because he observed that the turkeys 

 and ducks living with the infested hens were not attacked. He ob- 

 served the same malady in young pheasants at a time when they as- 

 sume the livery which distinguishes the two sexes, and in partridges 

 whether the locality was elevated or low and humid. 



Both Wiesenthal and Montagu recognized that this disease was caused 

 by worms occupying the trachea and extending occasionally to the phar- 

 ynx, but never as#'ar as the lungs. They found as many as twenty at- 

 tached to the mucous membrane, which, together with the lungs, was 

 in an inflamed condition. These entozoa, acting finally as an obstacle 

 to the passage of air, produced death by asphyxia. 



Wiesenthal did not occupy himself with the specific determination of 

 the worm, but Montagu regarded it as a distome, a fasciola (fluke) of a 

 particular kind, having a round cylindrical body with two sucking 

 disks, borne on two peduncles of unequal length. 



Kudolphi* and the authors of his time continued to regard the cause 

 of the gapes in the gallinaeeans as a distome, and included it in the spe- 

 cies JJistoma lineare (Rud.). 



Shortly after, helminthologists discovered, upon a variety of birds, a 

 curious parasite likewise inhabiting the trachea, but this time belong- 

 ing to the order of nematodes, and especially characterized by the sin- 

 gular habit of permanent union of the sexes. Sieboldt made it the type 

 of a new genus— the genus Syngamus ; later, however, yielding to the 

 observations of Kathusius, he renounced his first idea and united this 

 helminth with the strongyli in naming it Sir ongylus trach eali s.% 



After the creation of the genus Sclcrostoma by Dujardin, in which this 

 author unites the old strongyli possessing a mouth which is armed with 



*l'a1h. Societif of London, October 15, 1872, and Med. Times, 167*2, p. 474. 

 \ Medical and Physical Journal (1799), II, p. 204. 



[Account of a spec ies of fasciola v» hich infests the trachea of poultry, with a mode of 

 cure, Trans, of the Wernerian Nat, Hist. Society, I (1811), p. 195. 



