422 dr. j. murie on the sacs [June 16, 



the Hornbill group, the undermentioned instance (occurring in an 

 African species now alive in the Gardens) substantiating such a 

 view. 



The accompanying woodcut (fig. 1, A) illustrates the exterior 

 appearance of one of the objects in question. Its history is as fol- 

 lows : — "This case was thrown up by the Subcyliudrical Hornbill 

 (Buceros subcylindricus, Sclater), August 5th, 1872. The bird had 

 commenced to peck it to pieces and eat the fruit it contained at the 

 time it was thrown up. The keeper caught the bird (a male) iu the 

 act of eating it." The drawing (fig. 1, B) represents auother 

 of the sacs, which, as I was informed, came from the same bird, 

 but was cast up at a later date, the precise date not being noted. 

 Both retain, pretty correctly, the rugose character observable when 

 freshly expelled, although they were kept in spirits prior to being 

 sketched. That lettered A is much larger than B, on account of the 

 contained food having been removed and cotton in sufficient quantity 

 replaced, so as to prevent undue shrinkage. It is therefore of 

 tolerably natural dimensions. The fruit enclosed within B was left 

 in place ; but it, as well as the wall-membrane, had contracted very 

 considerably from its original size. The contrast between the two 

 is instructive as showing behaviour virtually the counterpart of the 

 corneous gastric texture ; and this similarity of tissue is confirmed 

 when a portion is dried, it then becoming translucent and brittle. 



It would be superfluous for me to say more concerning the exter- 

 nal aspect and contents of these figured sacs, other than that they 

 agree in every particular with Mr. Bartlett's, Professor Flower's, 

 and my own descriptions already published — with the exception that 

 the smaller one contained, in addition, a gooseberry. Their intimate 

 microscopic texture is of more consequence, and, as I apprehend, 

 affords a clue to the solution of the problem. For this reason I 

 have been particular in making accurate sketches under different 

 magnifying-powers. 



I may premise by stating that certain portions of the tissue of the 

 two sacs differ in one essential particular, this very discrepancy, 

 however, elucidating and tiding over a difficulty. In brief, it most 

 conclusively demonstrates that the constituents, at this part at least, 

 can be no other than the entire thickness of the horny layer of the 

 gizzard. According to the researches of Molin*, Flower f, Hasse %, 

 and others §, the inner coat of the gizzard in various orders and 



* " Sugli stomachi degli uccelli," in Denkshr. d. Acad, zu Wien, 1852, vol. 

 iii. pt. 2, p. 1, tab. i.-iv. A well-illustrated investigation. 



t " On the structure of the Gizzard of the Nicobar Pigeon and other Grani- 

 vorous Birds," P. Z. S. 1860, p. 330, pis. 175, 176. Substantiates the conclusions 

 of the foregoing author. 



J "Beitrage zur Histologie des Vogelmagens," Zeitsch. f. ration. Med. vol. 

 xxviii. p. 1. As bearing on the question of bird-secretions, see also his paper, 

 "Ueber den Oesophagus der Tauben, &c," Henle and Pi'euffer's Zeitsch. vol. 

 xxiii. p. 101. Also Bergmann " Einiges iiber den Driisenmagen der Vogel," 

 Reich. & D. B. Reymond's Archiv, 1862, p. 581. 



§ Berlin, in Ned. Lane. July and Aug. 1852, quoted by Kolliker ; but the ori- 

 ginal article I have not seen. Leydig, in his ' Histologic,' p. 309. gives an en- 



