M. Miiller on the Development of the Lycopodiacese. 113 



shown indeed, although not very distinctly, by a careful exami- 

 nation of Lycopodiuniy in which it may be observed that the base 

 of the sporangium is connected equally with the mid-nerve of the 

 leaf, in the axil of which it is situated, and with the stem, so that 

 its true point of insertion remains doubtful ; this condition how- 

 ever is better marked in Psilotum, especially in Tmesipteris, as 

 here the capsule is attached in the incisure of the leaf." The 

 author then comes to speak of Isoetes, where also two kinds of 

 spores occur, by which the affinity to Lycopodiacece is so distinctly 

 showTi, and says that in Isoetes the sporangia are decidedly not 

 axillary but proceed from the leaf, whereby it is rendered pro- 

 bable that this is also the case in the Lycopodiacece, and that the 

 sporangia are productions from the leaves. He further says, 

 p. 30, " The position of the sporangium on the leaf of Psilotum 

 might indeed be explained by an adhesion of the fruit- stalk to 

 the leaf, but on the other hand there is the opposing circumstance, 

 that in this family generally the fruit-stalk is remarkably short, 

 and in Isoetes no trace of it is to be found." 



A second evidence against Bischoff^s view is found by this au- 

 thor (Mohl) in the development of the spores contained in the 

 fruit of the lA/copodiacece, " since this takes place in the same 

 manner as in Ferns and the pollen-granules of the Phanerogamia, 

 in mother-cells which till the cavity of the fruit, and therefore 

 indicates that it occurs in the interior of a cellular organ even as 

 it does on the surface of a foliaceous part." — '^This circum- 

 stance," he says further, p. 31, " appears to have led Bischoff to 

 the assumption that the epidermis is wanting on the upper side of 

 the carpellary leaf. The assumption, that in the single carpellary 

 leaves, the face, folded inward, disappears either at first or during 

 the course of development, and that the cavity of the carpel be- 

 comes filled with mother-cells which originate from the naked 

 mesophyllum there present, is not indeed impossible in itself, but 

 it is too little supported by any analogy to allow of our accepting 

 it as valid without fm-ther examination of the point, in the pre- 

 sent case where the position of the fruit generally renders its de- 

 rivation from the leaf doubtful." 



By these statements, Mohl endeavours to controvert Bischoff's 

 view, and to render the other probable, that the sporangia of 

 Lycopodiacece. are productions from the leaves ; for he says, him- 

 self, finally (p. 33), " the fact of the sporangium oi Psilotum being 

 two- and three-chambered, cannot, as it appears to me, be brought 

 as an objection to the view thus proposed ; for this structure may 

 be explained as well by the growing together of two or three spo- 

 rangia, formed like the thecse of an anther, as by the union of 

 carpels, and this the more that we find an analogous fusion of 

 sporangia among the Ferns in Dancea and MarattiaJ' 



