OF THE OVARIUM OF SIPHONODON. 135 



the rounded shoulders of the column, in others not till after it has enveloped that organ. 

 It is at this period, however, tliat the important difference between my observations and 

 Mr. Griffith's occurs, and as it is upon this that the whole question of the placentation 

 turns, I have taken every means of endeavouring to arrive at the trath. Griffith says, 

 that at the period when the base of the central column becomes concealed by the growth 

 of the annulus, very young ovula may be detected, apparently attached around the whole 

 base of the column, and not pi'esenting any manifest relations with the carpeUary leaves. 

 He adds, that at this time a double long section had not shown him any solution of 

 continuity resulting from forcibly pulling back the carpeUary leaves (annulus) and thus 

 exposing the ovula. On the other hand, I, at no period, find the ovules to be developed 

 freely at the base of the column ; I have sought in vain between the annulus and column 

 for any such appearance, removing the annulus piecemeal with the utmost caution ; and 

 in every double vertical section that I have made, I have found the ovarian cavities to be 

 developed even at a much earlier period than that iadicated by Griffith, below the junction 

 of the annulus and column, manifestly within the substance of the ovary. The cavities 

 containing the ovules cannot at any period be exposed without tearing the annulus, which, 

 however, owing to the delicacy of the tissues and the excessive minuteness of the organs, 

 it is sometimes difficult to avoid doing. 



3. In the succeeding stage (fig. 5), the anthers are fuUy formed, and, arching inwards, 

 conceal the whole vertex of the ovary, leaving the apex of the column alone exposed 

 between their apices (fig. 8). The cylindrical portion of the column has lengthened, and is 

 terminated by a capitate stigma-Uke head ; its conical base is proportionally smaller and 

 more depressed. The annulus is very much thickened and grown in all dimensions ; it 

 has advanced up the column, and presents on a double vertical section two broad shoulders 

 embracing the col\imn, wMch it thus sheaths in a tube ; its upper surface is moulded by 

 the pressure of the anthers which lie between the five radiating ridges accurately described 

 by GriSith. The five teeth (figs. 8 ^ & 6 ^) terminating the ridges are now more promi- 

 nent, turn upwards, and are very cellular and fimbriated ; and a distinct groove is formed 

 on the surface of the annulus, close to its orifice and concentric vnth it. The ovarian 

 cavities are fully formed, linear-oblong, and all point outwards, but some upwards and 

 some downwards. The ovules are horizontal with an obscure lateral raphe, and each is 

 conformable to its cell. The column has an evident cuticle, as has also the contiguous wall 

 of the annulus. At this period vascular bundles appear in the ovary, and are traceable 

 downwards from each ovular insertion, and transparent lines are continued from each 

 ovule upwards into the annulus, to whose inner face these ascending lines are parallel and 

 contiguous. The tissues of the sheath of the annulus are pale and translucent. Mr. 

 Griffith says, that at this period the stigmatic surfaces will be found at the conical base of 

 the central column, at the point of its junction with the base of the annulus ; he says, 

 " tha lines of communication, by which each isolated ovulum is placed in the usual con- 

 ditions to receive the male influence, wiU be foimd to terminate on the circumference of 

 the conical base of the central column." On the contrary, I find the cuticle to be uni- 

 formly extended over the points indicated ; but its tissue is there rather looser, the cells 

 which form it being elongated inwards, giving when torn the appearance of stigmatic 



