312 BOTANICAL GAZETTE [may 
ever, it be supposed that, as is certainly the case in Anthoceros, 
the first wall formed in the Isoetes embryo is not the basal wall, 
but the transverse, there is much less difficulty. It is then 
possible to see how the root and foot may develop from the 
hypobasal hemisphere, not shaded in fig. 
7, while from the epibasal develops the 
strong cotyledon and a group of irregular 
cells which are generally regarded as 
constituting a portion of the foot, but 
should more probably be considered to be 
a poorly developed leaf-structure. Only 
half of what has been considered foot 
Wes Reb ris 'os in the Isoetes embryo is here retained in 
_Isoetes. that morphological category. The tt 
mainder is considered to be aborted leat 
functioning as foot. The true epibasal area gives rise to the 
shoot while the true hypobasal area gives rise to the root 
Thus the difficulty of supposing root to originate from » 
epibasal hemisphere is readily avoided, and by analogy with 
Anthoceros no violence is done to accepted ideas of embryology: 
In brief an Isoetes egg may be regarded as an Angiopteris ee 
turned through an angle of go° in the archegone cavity, an 
cut by the transverse wall before the epibasal wall appears: 
Embryogeny of Pteris—The leptosporangiate fern embryo has 
been studied by a large number of observers, the first — 
work being that of Hofmeister,” who made out correctly 
first divisions. As in the case of many of the lower ll 
complete study was accomplished later by other observ 
Goebel 2* contributed some important observations 10 a we 
Primarily devoted to prothallial structure, and Kienitz-Ger 
. der Fart 
» Ueber Entwickelungsgeschichte und Bau der Vegetationsorgané 
krauter. Abh. K. S, Gesellsch. Wiss. 5: 6 
. oD " s 5 OI 5. Leptophylla- 
*Entwickelungsgeschichte des Prothalliums von Gymnogrammé 
Bot. Zeit. 35: 689 1877 1 und 
ee : .Kapse 
* Untersuchungen iiber die Entwickelungsgeschichte der Laubmoos 
‘ ; i 1878. 
die Embryo-Entwickelung einigen Polypodiaceen. Bot. Zeit. g0: 4%" * 
