535 . 



Ovuminovo. 



This specimen was also obtained during the practical enibryological 

 class-work in this College. It seems of sufficient interest to record 

 for although the number of such abnormalities is fairly large some- 

 where between 30 and 40 they range from that of Young 1671 quoted 

 by Davaine (6) up to the present time and so represent an extremely 

 small proportion of the total number of eggs that must have come 

 under observation. For a complete list reference should be made to 

 the works of Parona and Grassi (10), Davaine (1. c.) and Herrick (7). 



In the specimen under discussion the enveloping egg was of normal 

 size (64 mm X 42 mm) and contained a yolk of normal appearance 

 which had been displaced towards the narrow end of the egg. Although 

 it had been incubated for 48 hours there was no sign of a blasto- 

 derm. The included egg was of small size (26 mm X 16 dqim) and 

 enclosed in a shell which was quite hard and brittle although much 

 coarser in grain than in the ordinary case and attached immovably 

 to the vitelline membrane of the larger yolk. This condition differs 

 from the unique specimen described by Herrick where the small egg 

 is inside the yolk of the larger and from the usual cases in which it 

 is quite free in the albumen and appears to be somewhat intermediate. 

 On opening the enclosed egg it was found to contain a shell mem- 

 brane and albumen. There was no definite yolk but at one pole the 

 albumen contained a small diffuse mass of yolk substance. 



In adopting the classification of such abnormalities given by Her- 

 rick (loc. cit.) this would be placed in Division 1, i. e. "Enveloping 

 egg usually normal, but occasionally of large size ; blastoderm recorded 

 in at least one instance" and Section (b), i. e. "In albumen, small 

 composed usually of shell, shell membrane, albumen and rarely with 

 yolk; few cases recorded." 



It would appear to be quite in accord with the theory given by 

 several writers that the small egg is produced by the rupture of a 

 larger egg and the fragment is then treated as a separate egg in the 

 oviduct and receives a shell. For some reason it is not laid and the 

 next egg coming down the oviduct envelopes it before itself becoming 

 enclosed in a shell. 



Literature. 



1) AssHETON, R., Journ. Anat. and Physiol., Vol. 82, 1898. 



2) Bryce, T. H., Proc. Roy. Soc. Edin., 1899. 



3) BuRCKHARDT, R., Arch. f. Anat. and Physiol., 1888. 



4) Cleland, J., Mem. and Memoranda Anat., 1886. 



