THE HIGHER CRYPTOGAMIA. 315 



from the bundles adjoining the sides ^of the meshes of the 

 reticulated vascular bundles of the stem ; their position 

 with regard to the fronds is not a definite one. OpMo- 

 glossum vulgatum (like 0. pedunculosuiii), is often repro- 

 duced by root-buds. The new plant is reproduced by 

 the multiplication of a cambial cell of the vascular bundle 

 which traverses the longitudinal axis of the widely-creeping 

 adventitious root, and is at first concealed in the cortical 

 parenchyma of the root. However, this mode of repro- 

 duction is not so essential for the economy of the plant as in 

 0. pedunculosum, a species which may be called mono- 

 corpous, inasmuch as its shoots usually die of? when they 

 have brought forth sporangia : its perennial duration rests, 

 it may be said, exclusively upon the adventitious shoots of 

 the roots.* 



The appearance of fertile fronds on the front surface of 

 the sterile ones is the same in Ophioglossum as in Botry- 

 chium, and justifies the same conclusion, viz., that the 

 fertile frond is a shoot of the sterile one. 



Mettenius has published some observations upon the 

 germination of Ophioglossum ( c Farrne des Leipz. Botan. 

 Gartens,' Leipzig, 1856,' p. 119). He found the sub- 

 terranean prothallia and germ-plants of Ophioglossum 

 2)endunciilosiim growing in the neighbourhood of the 

 mother- plants. Artificial sowings of the spores were un- 

 successful. The youngest prothallia which he found con- 

 sisted of a small globular knob, of from ^) to 1^ lines 

 in diameter, from which a conical prolongation of about 

 two lines in length proceeded. The delicate -walled cells of 

 the parenchymatal tissue of this knob were filled with 

 amyloid granules : the superficial cells, and the capillary 

 roots proceeding from them, were already dead. The 

 formation of the knob was thus already ended, and the 

 growth of the prothallium limited to the prolongation, 

 whose cells filled with thick protoplasm, were in an active 

 state of division. In older prothallia the prolongation 

 attains a considerable length, as much as two inches. Its 

 growth arises from the repeated division of a single apical 

 cell by means of oblique septa. The daughter-cells ap- 

 * Like Tyrola tiniflora. See Irmisch in 'Bot. Zeit.,' 1856. 



