Further than this the spore alone has no power to go, and the prothallium is not truly the germ of the future plant.
As soon as the fern is firmly established, the prothallium withers away.
The prothallium is of a peculiar dull-green colour, different from that of the young frond which is subsequently formed.
The neck of the archegonium is quite long, but does not project above the surface of the prothallium (Fig. 77, H).
To make these, the prothallium should be placed between small pieces of pith, and the razor must be very sharp.
In the upper part of the prothallium several large archegonia are formed in much the same way as in the pteridophytes.
At a later period, other organs are found also on the back of the prothallium.