486 Mr. Valentine on the Structure aud Developmeut 



of the sporule, where they lie quite concealed by the germ, little fibnlliie or 

 rootlets begin to shoot from one side. They are simply articulated tubes, or 

 elongated cells applied end to end, with frequently a bulbous extremity; and 

 each is produced from one of the cells of the germ (Tab. XXXIV. fig. 14.). 

 They differ much in length in different sporules ; in some they are not longer 

 than the sporule, M'hilst in otiiers they are thr(;e 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 fibrillœ, begins to 

 change, the cells becoming flatter and more intimately connected 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 (Tab. XXXIV. 

 fig. IG.). The germ now gradually points in two places, which are by no means 

 fixed, but occur in various situations according to the position of the sporule 

 in relation to the light. The direction of the first leaf is generally in the di- 

 rection of the axis of the sporule, or rather a little inclined ; and that of the first 

 root at right angles, or kiteral, but very soon changing 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 Inioyant in the water, exposes 

 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, containing 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 

 has 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 than the sporule ; whilst the root, although 

 more backward in its development, pierces its sheath before it becomes as 



