Mr. Gnirrrra on the Development of the Ovulum in Avicennia, 3 
same line, or rather between the inner cotyledon and body of the ovulum, 
becomes enlarged and flattened almost into a membrane ; and even when the 
cotyledons are as long as the placenta, this part of the albuminous tissue 
equals them in length (Tas. I. fig. 13.). 
The mature embryo, with the exception of its radicle, which is always im- 
bedded in the albuminous tissue, may be.said to be naked. "The upper part 
of the albumen at this period is much dilated, and almost membranous ; the 
edges are very irregular (Tas. I. figs. 13 & 14.). 
The conduplication of the cotyledons takes place at an early period ; their 
inequality at a much earlier, even before the protrusion of their points. 
The central prolongation of the sac was not observed later than the period 
represented by fig. 12. Tas. L, but it is probable from appearances that it is 
at length filled with albuminous tissue. 
The exact distance to which the vascular fascicle at length reaches was not 
observed: probably it extends, when complete, to the apex of the short central 
prolongation of the sac. 
The above observations were made very shortly before my departure from 
Malacca: they are deficient in several respects ; but of the mode by which the 
embryo becomes external to the seed to so great a degree I can speak with 
the requisite confidence. 
I now proceed to offer my remarks on the circumstances detailed above. 
The elongation of the posterior end of the embryo-sac, occurring as it does 
in a plant so different in general organization from those in which it has 
hitherto been observed, appears to me remarkable. It is curious that this 
prolongation has only been observed in association with a particular form of 
the free central placenta, and thus the exact observation of the corresponding 
developments in Olax and Congea becomes more desirable than ever. 
The shape of the embryo-sac in that stage, represented by fig. 7. Tan. L., 
is also worthy of notice: so far as I know, it is the only instance of an 
embryo-sac prolonged posteriorly, it may be said, from two points of its 
surface, or which may not be considered to be in itself a rectilinear body. 
The general analogy of the relations of the embryo-sac with the nucleus would 
lead me to suppose that the embryo-sac of Avicennia consisted originally of 
that part in the axis of the ovulum, viz. the head or dilated end, and what I 
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