30 A. Henfrey on the Higher Cryptogamous Plants. 
nutriment.””. The embryo then breaks through the coats; the 
first leaf above and the first root below, the coats remaining  at+ 
tached over the central mass of the embryo. The subsequent 
changes need not be mentioued here, further than to state that 
the leaves succeed each other alternately, and are not opposite as 
in the Lycopodiaceze ; moreover no internodes are developed. be- 
tween them, so that the stem is represented by a flat rhizome; 
like the base of the bulb of many Monocotyledons. 
In the paper by Dr. Mettenius,* already alluded to, we find, 
some very important modifications of, and additions to, this his- 
tory of development of the spores of Jsoées, bringing them into ~ 
more immediate relation with the other vascular Cryptogams. © 
s author describes the spore-cell as a thick structure com- 
sed of several layers; in some cases he counted four. It com- 
pletely invests the pro-embryo, which is a globular cellular body 
filling the spore-cell. Among the cells of the outermost layer 
the pro-embryo (which layer forms the naecleus of Dr. Miller), 
on the upper part, are produced the ovules, fewer in number than 
in Selaginelia, arranged i in three rows converging upon the sum- 
mit of the spore, these rows corresponding to the: slits between 
the lobes of the outer coat of the spore. The four superficial. 
cells of the ovules (which are evidently the peculiar groups men- 
tioned by Miller and previously noticed by Valentine)t grow 
much in the same way asin the Rhizocarpee and in Selaginella, 
into short papille. The embryo is developed in the substance of 
the pre-embryo, displacing and destroying its cells, and a globular 
portion (corresponding to the “reservoir of nutrition” of Miller) 
remains within the spore after the first leaf and rootlet have made — 
their way out. ‘This body is the analogue of that portion.of the” 
embryo of Selaginella which penetrates into the cavity of er: 
spore, and to the end of the first axis in the Rhizocar 
‘The most important point, however, of Dr. Mettenius’s. re- 
to trace all the stages of. development of these spiral filaments 
from the small spores, but he obtained nearly all the evidence 
relating to their origin which Nageli has done in reference to the 
similar organs in the Pilularia.{ In the small ann minute 
vesicles are produced of varying size aud number, se 
the outer coat. The inner coat or spore-cell breaks pene the 
outer coat either in the middle or at both ends at the projecting 
ridges, by which they are originally in contact with the other 
spore-cells. Its contents are expelled, as is proved by finding 
numerous empty meimbranes. The expelled vesicles are met with 
* Beitrige zur Botanik. Heidelberg, 1850. + Linnean Transactions, netions, vol. x7 xvii 
¢ Zeitschrift fir r Wiss, Botanik, Heft 8. Zurich, 1846, 
