100 



Dr. Davy on the Bursa Fabricii. 



[Apr. 19, 



In another, an older bird (judging from its appearance), shot at the same 

 time, there was no trace of a bursa* ; and the same remark appUes to a 

 third examined in Januaiy. 



XXIV. Common Starling (Sturnus vulgaris). — Of a young one shot on 

 the 29th of June, the bursa was about the size of that of theyoung thrush. In 

 two old birds shot on the 7th of March, not a trace of the organ was found. 



XXV. Skylark (Alauda arvensis). — In two examined in January there 

 was the like deficiency. 



XXVI. Chiffchaff (Trochilus minor). — Of one, a young bird, exa-^ 

 mined on the 14th of July, the bursa, of moderate size, contained a little 

 fsecal matter. In another, an older bird, shot in March no bursa could 

 be found. 



XXVII. Robin (Sylvia rubecula). — Of a young one found dead on the 

 16th of June, still warm, weight 25.5 grs., the bursa was of moderate size. 



Of another, nearly fully fledged, found dead on the 25th of June, weight 

 285 grs., the bursa was comparatively large, exceeding a little in size that 

 of the preceding. 



XXVIII. Yellow Ammer (Emberiza citrinella). — In one, a male, its testes 

 abounding in spermatozoa, examined on the 16th of June, there was no 

 trace of a bursa. 



XXIX. Blue Tit (Parus cseruleus). — Of two young ones examined on 

 the 8th of June, when just able to fly, one weighing 177'5 grs., the other 

 162 grs., the bursa was comparatively large ; in each it was empty. 



XXX. Cole Tit (P. ater). — In one examined in February no trace of the 

 organ could be found. 



XXXI. Martin (Hirundo urbica). — Of three young ones taken from 

 the nest on the 10th of July, the bursa was comparatively large; in each 

 it was empty. One nestling weighed 414 grs., another 398 grs., the third 

 423*5 grs. The parent birds were both found of less weight ; that of the 

 male was 263 grs., of the female 287*4 grs. In the latter a distinct bursa 

 was found, little less than that of the young birds. Search was made for 

 spermatozoa, but none were found in it. Of the male, the pelvis was so in- 

 jured by shot that it was useless for examination. In a male shot on the 

 1st of August, the testes of which contained spermatozoa, no trace of a 

 bursa was found. 



From the preceding results may not the following conclusions be 

 drawn ? — 



1st, That in some birds, as in the common fowl, and probably in all the 

 gallinaceous family, and that of the Anatidse, the bursa increases in size 

 and in completeness of organization up to a certain age, beyond which it 

 gradually diminishes equally in both sexes, and eventually disappears. 



2nd. That in other birds, those of rapid growth, which take wing as 



It was shot near the river Brathy, in which charr were then spawning. In its giz- 

 zai'd and cesophagus nine ova of this fish were found ; they were transparent when ex- 

 tracted, but immersed in water they soon became opaque. 



