Prof. Ehlers on the Development of Syngamus trachealis. 239 



I first heard this tit coughing ; but it had struck rae a few- 

 days previously that the bird was quieter than usual, although 

 in other respects it showed no symptoms to indicate disease. 

 On the next morning I examined the freshly evacuated faeces of 

 the bird, and found in them ova of Syngamus in the usual state 

 of development. I killed the tit, and found in its trachea two 

 pairs of Syngami in copula — a large pair, of which the female 

 Avas swelled with mature ova, and a smaller pair, the female of 

 which bore only a few mature ova. From the administration 

 of the embryoniferous ova to the time when the disease mani- 

 fested itself and the Syngami weve sexually mature, 17 days 

 had elapsed. 



A canary to which I had administered embryoniferous ova 

 in the same way, couglied within seven days, and presented 

 remarkable difficulty of breathing ; but its faeces contained no 

 developed ova. On the twelfth day after feeding I killed it, 

 and found in the trachea twelve j)airs of small Syngami in 

 cojndd, but without matured ova. Here the worms produced 

 the diseased phenomena in the trachea of the bird before they 

 had attained full sexual matm'ity ; and this explains the 

 absence of the ova in the faeces. 



My investigations are not yet completed. I have still to 

 ascertain the mode of immigration into the trachea, as I am 

 by no means certain whether during the pouring in of the 

 ova they remain adherent at the entrance of the larynx and 

 the W' hole development takes place in the trachea or the lungs 

 and airsacs, or whether the ova are swallowed (which in my 

 experiments was certainly the case with the majority of them) 

 and the young then quit the egg-shell in the intestine of the 

 bird, bore through the wall of the stomach or intestine, and, 

 entering into the airsacs, thus obtain access to the trachea. 

 From what I have as yet observed in connexion with this, the 

 former would appear to be the way in which the immigration 

 takes place. 



Upon this, and upon the structure of the full-grown and of 

 the developing animal, I shall report elsewhere in detail, wuth 

 reference to the existing literature of the subject. My object 

 in this communication was to state that the ova of Syhgamus 

 in the open and under various conditions, when deposited in 

 moist localities either with the fasces or the ejections from the 

 trachea of the bird, become so far developed that the parasites 

 escape from them as soon as they are taken up by a bird. By 

 this means a course is to a certain extent indicated in which, 

 by preventive measures, we may protect poultry-yards or 

 aviaries from the immoderate and destructive diffusion of these 

 parasites. Careful observation of coughing birds, in which 



