OF FERNS FROM THEIR SPORES, | 127 
in the embryo-sac. "The succeeding stages of growth of this new cellular body, the embryo, 
consist of a gradual multiplication of the cells by division, and expansion of the new struc- 
ture, until at length the rudiments of a radicle and the first leaf become visible as projec- 
tions from the surface, resulting from the more rapid increase of the cells in the situation 
where they are found (figs. 76—79). 
-Tn the ulterior development of the embryo the radicle appears to be arrested in its deve- 
lopment, and to remain as a cellular mass (fig. 80a) within the cavity of the prothallium, 
until it disappears with the latter by decay. The first leaf unfolds upwards and forwards 
(fig. 80 2) towards the notch of the prothallium, and the first adventitious root (fig. 80 c) 
breaks through at the base of this towards the posterior border of the prothallium, exhi- 
biting a coleorhize like that of the Monocotyledons. The second leaf arises near the axil 
of the first, one-third of the circumference of the nascent stem to the side; the third leaf 
arises one-third to the side of the second, so that the three leaves form a circle, in which 
they stand at equal distances, and the fourth leaf arises over the first (Gymnogramma 
chrysophylla?). They are of very simple structure, consisting of cellular plates with twice- 
forked rudimentary nervures, and they are accompanied by very elegant ramenta at the 
bases of the little petioles (figs. 81-83). 
I have not followed the development beyond the formation of the fourth leaf (fig. 83), 
by which epoch the prothallium has generally decayed away from the base of the young 
stem. 
V. CRITICISM OF PREVIOUS OBSERVATIONS. 
The first account of any of the peculiar structures above described was published in 
1844 by Nägeli*, in a memoir entitled “Moving Spiral Filaments (spermatic filaments) in 
Ferns,” wherein he announced the existence of the bodies now called antheridia, but mis- 
taking the archegonia for modified forms of the antheridia, he was led away from a minute 
investigation of them. If he had followed the development of the prothallia further, he 
would have detected the relations of the nascent embryo, which would probably have put 
him on the right track. As it was, the remarkable discovery of the moving spiral fila- 
ments, or spermatozoids, occupied all his attention, and caused him to fall into error in 
certain important respects; for example, in fig. 11 of his plate, he has represented what 
is undoubtedly an archegonium, filled with cellules (sperm-cells), which, he states, emerged 
from it as from the antheridia: this is undoubtedly incorrect. 
With regard to the spermatozoids his description is imperfect, the only indication of the 
existence of cilia being a statement that he occasionally saw a long filiform appendage, 
like that represented by Meyen in the spermatozoids of Chara. On the other hand, the 
mathematical definition of the movements of the spermatozoids is surely misplaced, since 
nothin be more arbi or irregular than their course. 
ee whatever be ai ee it is certain that it is to the keenly 
inquiring spirit of this author that we owe the first step of the investigations which have 
thrown so much light upon the reproduction of the higher Cryptogamia. eai 
Nägeli’s observations remained without confirmation or criticism until the publication 
* Zeitschrift fur wiss. Botanik. Heft i. 168. Zürich, 1844. ; 
S 
