236 Prof. Ehlers o?? the Development of Syngamus tracliealis. 



The other numbers correspond exactly with the preceding ; 

 but these suffice to enable us to appreciate what takes place. 



It is likewise useless to prolong further the extracts from 

 these works. What we have said is sufficient to show their 

 general character, and the importance of the results already 

 obtained. 



We here terminate this rapid and necessarily imperfect re- 

 vision. But the quantity of materials is considerable, the 

 subjects treated are very varied, and it is very difficult to 

 bring the whole within the limits of a single essay. We hope 

 on another occasion to be able to complete what is deficient here. 



XXV. — On the Development o/" Syngamus tracliealis. 

 By Prof. Ehlers*. 



I AM indebted to the kindness of Baron von Freyburg, of 

 Regensburg, for the opportunity of tracing experimentally the 

 course of development of this worm, which is parasitic in the 

 tracheae of birds, and, when it occurs in quantity in aviaries, 

 pheasantries, and poultry -yards, produces considerable losses by 

 the destruction especially of young and weakly animals. The 

 parasite was introduced with some exotic birds into the aviary 

 of the Baron von Freyberg during the illness of its owner, and 

 has since occurred there more or less abundantly. The birds 

 attacked by the worm betray this generally at first by a pecu- 

 liar cough, during which they frequently throw the head to 

 and fro, and not unfrequently at the same time expel small 

 masses, which they generally pick up and swallow imme- 

 diately. Large birds bear the parasitism of the worm, if it 

 does not occur in too large numbers, for a long time ; small 

 birds, on the contrary, often die suddenly — it would appear, 

 especially by the pair of worms (which, as has long been 

 known, reside in the trachea usually in coi^ula) placing them- 

 selves in such a position that the passage of the air-tubes is 

 stopped, and the birds are suffocated. 



In a Cardinalis virginianus which M. von Freyberg gave 

 me for examination, and which, according to him, had long 

 been infested by Syngamus^ I could see the animals in the 

 entrance to the upper larynx, and take them out with a fine 

 forceps. In freshly infected tits, the mucous membrane of 

 the throat was more strongly reddened than usual, and exhi- 

 bited some very fully charged superficial veins. But the most 



* From the * Sitzungsberichte der phys.-med. Societat zu Erlangen,' 

 Dec. 5, 1871. Translated by W. S. Dallas, F.L.S., from a separate copy 

 communicated by the Author. 



