70 CURREY, ON THE HIGHER CRYPTOGAMIA. 
the prothallium of the Rhizocarpez and Selaginelle. The structure of 
the corpuscula bears the most striking resemblance to that of the arche- 
gonia of the Salviniz, and still more of the Selaginelle. Irrespective of 
the different mode of impregnation—which in the Rhizocarpee and Sela- 
ginelle takes place by free spermatozoa, and in the Conifer by a pollen- 
tube, in the interior of which spermatozoa are probably formed—the 
transformation of the germinal vesicle into the primary mother-cell of the 
new plant in the Conifere and the vascular cryptogams, only differs in 
the fact, that in the latter there is usually one single germinal vesicle 
only, whilst in the former there are very numerous germinal vesicles, of 
which, normally, one only is impregnated. The embryo-sac of the Coni- 
ferze may be looked upon asa spore remaining enclosed in its sporangium ; 
the prothallium which it forms does not come to the light. In order to 
reach the archegonia of this prothallium the impregnative matter must 
make itself a passage through the tissue of the sporangium. 
Moreover, the development of the pollen of the Coniferee, when dis- 
persed, varies in a marked manner from that of pheenogams, and exhibits 
vital phenomena similar to those met with in the microspores of Pilularia, 
Salvinia, and Isoetes. The extinction of its sexual function (the protru- 
sion of the pollen-tube) is preceded by a cell-formation in its interior, of 
which no instance is to be found amongst monocotyledons and dico- 
tyledons. 
Two of the phenomena which have led me to compare the embryo-sac 
of the Coniferze with the large spores of the higher cryptogams, is common 
to the embryo-sac of phznogams, viz., the origin of the ovule from an 
axile cell, and the want of connexion with the adjoining cellular tissue. 
This is very remarkable in the Rhinanthacee on account of the indepen- 
dent growth of the embryo-sac. The Conifers are closely allied to the 
phenogams in the fact that their pollen-grains develope tubes. 
The phznogams therefore form the upper terminal link of a series, the 
members of which are the Coniferae and Cycadex, the vascular crypto- 
gams, the Muscinee, and the Characee. These members exhibit a con- 
tinually more extensive and more independent vegetative existence in 
proportion to the gradually descending rank of the generation preceding 
impregnation, which generation is developed from reproductive cells cast 
off from the organism itself. The closing members of this series, the 
Characez, pass through their entire vegetative development in this gene- 
ration, whilst the vital phenomena of the generation which follows 
impregnation are limited to the filling with oil and starch of the newly- 
formed cell in the central cell of the fruit-branch or archegonium. The 
development of the latter generation in the Muscinez is far more impor- 
tant, although in some instances, as for example in Riccia, it is very 
limited in comparison with the first generation, that, namely, which pre- 
cedes impregnation.* This state of things is reversed in the Ferns, the 
Equiseta, and the Ophioglosserx. From the Characezx up to these orders, 
there is an uncertainty in the different species as to the sexual function 
of the reproductive cells which are cast off from the organism itself, viz., 
* Anthoceros—which in the development of the second generation 
stands very low in the scale—exhibits a remarkable analogy with the 
Charace, in the fact that, as in the latter, the formation of its antheridia 
commences by the growing out of the cells of the wall of an intercellular 
eavity. The well-known red globules of Chara are manifestly states of 
antheridia. Cavities communicating with one another are formed round 
the middle point of the hitherto solid globular mass of cells, within which 
cavities the antheridia—or cellular threads in whose joints the vesicles 
which produce the spermatozoa are formed—become developed. 
