24 Linnean Society. [March 19, 



did I not find several similar spaces on the germinating sporules of 

 Isoetes lacustris, which I could not refer to such an origin : it must 

 be observed however that I have not seen the earlier stages of germi- 

 nation in Isoetes. Soon after the exposure of the entire germ, which 

 is effected by the reflexion of the valves and conical membrane over 

 the side of the sporule, where they lie quite concealed by the germ, 

 little fibrillse or rootlets begin to shoot from one side. They are 

 simply articulated tubes or elongated cells applied end to end wdth 

 frequently a bulbous extremity, and each is produced from one of 

 the cells of the germ. They differ much in length in different 

 sporules ; in some they are not longer than the sporule, whilst in 

 others they are three or four times that length, and, in common with 

 the cells of the germ, contain granules which in these are colourless 

 but in the germ green. The cluster-like appearance of the cells 

 which form the germ, soon after the appearance of these fibrillse be- 

 gin to change, the cells becoming flatter and more intimately con- 

 nected with each other. At the same time an internal change is taking 

 place, for by a gradual arching or receding upwards of that part of 

 the germ which closes the cavity of the sporule the germ becomes 

 hollow, the hollow communicating with the cavity of the sporule, 

 which is of course proportionably enlarged. The germ now gra- 

 dually points in two places, which are by no means fixed, but occur 

 in various situations according to the position of the sporule in rela- 

 tion to the light. The direction of the first leaf is generally in the 

 direction of the axis of the sporule, or rather a little inclined, and 

 that of the first root at right angles or lateral, but very soon chan- 

 ghig to an opposite direction to that of the leaf. This would be the 

 constant direction if the sporules were always left to themselves free 

 from entanglements, on account of the peculiar structure of their 

 outer coats ; the spongy fibro-cellular texture of the superior third 

 of which, causing that end to be the most buoyant in the water, ex- 

 poses the superior surface of the germ to the direct action of the 

 light ; but as it cannot always happen that the sporules should be 

 free, the direction of the leaf and root is sometimes quite the reverse, 

 and at others both leaf and root are lateral, but proceeding from 

 opposite sides of the germ. These two points gradually lengthen, 

 and if dissected each will be found to consist of a closed sheath, con- 

 taining in one instance the leaf, in the other the root in the form of 

 a conical process like a finger in a glove. The young leaf, which is 

 taper and its cells crowded with green granules, being in advance of 

 the root, which is obtuse and destitute of green granules, bursts 

 through the summit of its sheath when it has become rather longer 



