34 A. Henfrey on the Higher Cryptogamous Plants. 
layer of smaller ones. The smaller cells covering ‘the apex of 
this large cell, four in number, elongate into a papilla before the 
pro-embryo bursts through the exine, which splits regularly into 
twelve to sixteen teeth ;—subsequently they become divided by 
horizontal walls, and then appear as the organ which Schleiden, 
and after him Mettenius, supposed to be ‘ pollen-tubes’ produced 
from some of the small spores. These papilliform cells mostcet- 
tainly originate from the pro-embryo, a fact which takes away 
all material ground from Schleiden’s theory. 
he four papilliform cells separate from each other and. leave 
a passage leading to the large central cell. In this cell the young 
plant origitistes shortly after the smaller spores, which never pro- 
duce ‘pollen-tubes,’ begin to emit the onluick santana spiral 
filaments discovered by Nageli. 1 observed a sected out an 
embryo consisting of only four cells. It cpa filled me 
large central sil and there was not the least trace of a pol 
tube attache 
“ The ane of Salvinia is somewhat different from this. 
On every pro-embryo, several, as many as eight, cells of the outer 
surface of the cellular layer next but two to the obtuse triangular 
cellular body, acquire a considerable size, a spherical form, and 
become filled with protoplasm; the four cells covering each 0 
these larger cells lose the greater part of their chlorophyll oa 
separate from each other to leave a passage leading down to the 
large central cell, In this large cell the young plant originates, 
The number of these organs in Salvinia allows the possibilit ty of 
the occurrence of pol y-embryony in this genus; I observed ‘ee 
embryos on one pro-embryo i In one case. 
“It is out of the question to talk of a ‘larger pollen-tube?.in 
Salvinia. Mettenius has already shown that the structure of the 
small spores renders such a product from them impossible.” 9 | 
Dr. Mettenius’s Essay on the Vascular Cryptogams,* already 
frequently referred to, confirms the preceding account in all essen- 
tial points, some slight criticisms relating only to the structure: of 
the coats of the spore ; and it adds a description of the develop- 
ment of the ‘ovules’: in the pro-embryo of Marsilea Fabri, which 
agrees closely with that in Pilularia. Hofmeister} has recently 
announced the discovery of the production of cellules containing 
spiral filaments a oe small spores in Salvinia, just as Nagel 
saw them in 
i oelees Conclusions. 
In the facts of which I have given confessedly a very sa 
fect resumé in the preceding pages, we have two important points 
to consider. In the first place, we have to determine how fat 
Ph a 
* Beitrige sur Botatile Heidelberg, 1850. 
Br Ties tg Pp. 700 (in a note to a review of Mercklin’s Bssay on the Reprodue 
4 
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