576 MR. W. C. WORSDELL ON THE DEVELOPMENT 
within the outer chlorophyll layer, either fixed or at first swimming 
with the rotation-current, and, when the crisis was over, becoming 
fixed again. These chlorophyll grains are always underneath the 
dead chlorophyll layer. That they possess a fairly active power 
of assimilation is shown by the fact that they commonly contain 
small starch grains as well as by the amount of oxygen they 
can evolve. 
The phenomena above described, and more especially the fact 
that cells in which all the chloroplastids, with the exception of a 
very few which accidentally escaped and which were barely able 
to provide sufficient assimilatory material for the subsistence 
of the cell, could nevertheless remain living, though incapable of 
regenerating fresh chlorophyll, for a period of a year, forms an 
excellent illustration of the relative independence of chloroplastid 
and cell-plasma, and of the much greater sensitivity of the 
former to the action of sunlight. 
On the Development of the Ovule of Cj intisonia a Genus of 
the Orobanchacee. By W. C. WonsPELL. (Communicated : 
by Prof. J. B. Farmer, M.A., F.L.S.) 
[Read 17th December, 1896.] 
(Prates XX.-XXII.) 
Havine at my disposal material of three species of Christisonia, 
whose vegetative structures I described in a former paper*, I was 
able, by the aid of microtome-sections, to study the embryological 
development of these plants from the earliest stage to that of the | 
mature seed. 
L. Koch f, in his work on Orobanche, has described, in the fullest 
detail, the development of the ovule in that plant. From my 
own observations on Christisonia it would appear that the latter 
plant isessentially similar to Orobanche in this respect; so that I 
have in this contribution nothing really new to bring forward on 
this subject. At the same time, from the fact that CAristisonia 
in its general habit and vegetative structure presents important 
* “On the Comparative Anatomy of certain Species of the Genus Christisonia,” 
Ann. Bot. vol. ix. 1895. 
t ‘Die Entwickelungsgeschichte der Orobanchen,’ 1887. 
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