248 CONTRIBUTIONS TO 
If we now assume a cell to be completely filled with a 
transparent solution of sugar in which there is rapidly gene- 
rated just so much gum, as may form, by an equally quick 
conversion into jelly, a delicate cell-membrane, the exist- 
ence of which we cannot possibly recognise with the micro- 
scope, in consequence of the similar refracting power of the 
wall, the contents, and the surrounding medium ; it then be- 
comes exceedingly probable that a number of such formative 
processes may go on which escape our observation, and become 
known to us only in their results, when, after the absorption 
of the parent-cell, we suddenly find two new ones in its place. 
If, on the other hand, our attention has been previously directed 
to this process, we have, in the application of reagents, espe- 
cially iodine, which is quite indispensable to the physiological 
botanist, several means of rendering it visible in instances 
where it is suspected to be going forward. Gradual transition 
to the completely invisible processes are readily found by more 
extended investigation ; I will just mention one of the most 
difficult instances which I have met with, by way of example. 
It occurs in the germination of the sporules of Marchantia poly- 
morpha. Only a few, generally only from two to four of the 
cell-nuclei which appear in the sporules, serve for the formation 
of cells; the others become quickly enveloped with chlorophyll, 
and are thus withdrawn from the vital process. The transparent 
fluid, however, in which these cytoblasts float, passes through 
the remaining stages of the metamorphosis into cell-membrane 
only just at the boundary of the latter, and with such rapidity 
that the exceedingly delicate young cells cannot be distin- 
guished by anything else than a minute, generally more or less 
uninterrupted circle of infinitely small, black granules, and by 
a scarcely perceptible greater transparency of the contents of 
the newly-formed cells in comparison with that of the parent- 
cell, and finally, under the most favorable circumstances, by the 
spot at which the newly-developed cells come into contact, the 
point of juncture being still covered by the membrane of the 
parent-cell. (Pl. I, figs. 18-20.) This may perhaps be general 
in the Cryptogamia, and especially in water plants, and probably 
Mohl’s division of the cells of Conferve may be thus explained. 
If we consider, however, that there are undoubtedly many 
plants, among which the Fungi and infusorial A/ge should pro- 
