266 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



growing shoot was forced to make a half turn to assume its normal, 

 negatively geotropic position. 



In 1856, Mettenius^ published an account of the sexual phase of 

 Ophioglossum pedunculosum, which he found in considerable quantities, 

 in the earth of the pots containing the adult spore-plants. Attempts to 

 germinate the spores, under observation, failed also in this case. The 

 youngest prothallia were tuber-like in shape, and one to three milli- 

 metres in thickness. Out of the tuber grew subsequently a conical 

 process which elongated considerably (four to fifty millimetres), and 

 sometimes branched. At the tip of the outgrowth, or of its ramifications, 

 was found an apical cell, sometimes at least, of triangular pyramidal 

 shape. The cylindrical portion of the prothallus grew upwards towards 

 the surface of the soil, but, on reaching the light, became green and 

 died away at the apex, or divided into two or three lobes which 

 flattened out on the earth and developed no further. The tuber was 

 composed of starch-laden parenchyma. In the process some textural 

 differentiation was found, there being an axial, elongated, starch-free 

 strand, surrounded by short starch-bearing cells. Both kinds of sexual 

 organs were found in the same plant and not arranged in any definite 

 order, but generally situated on the cylindrical process. The antJieridia 

 were large in size and their wall was generally two layers of cells in 

 thickness. The antherozoids were large also, and composed of one 

 and a-half to two spiral turns. The antJieridium opened by a pore 

 produced by the breaking away of two superimposed cells in its wall. 

 The aperture was generally situated in that part of the wall nearest the 

 ;apex of the prothallium. The spermatozoids swarmed out of the 

 mother cells and about in the cavity of the antJieridium before making 

 their way out. The archegonia originated from two superficial cells, the 

 upper of which gave rise by repeated divisions to a neck of three to five 

 tiers of cells ; the lower formed the axial row, which were not, hovvever, 

 made out individually by this writer. On account of the small number 

 of embryos found, it was impossible to follow stage by stage, their 

 development. Nothing was noted in regard to the formation of the first 

 dividino- walls. The youngest embryo was oval in shape and already 

 sec-mented into a number of cells. The older ones were similar in 

 configuration, but of larger size. The anterior end of the elliptical 

 embryo grew through the tissues of the prothallium towards its apex, 

 and bursting forth sooner or later, became the cotyledon, green in 

 colour, and lanceolate in outline. The root developed more slowly and 

 bored its way directly outwards. A rounded protuberance at the 



2. Filices Horti Botanici Lipsiensis, pp. 1 19-120. 



