1)4 PHILOSOPHICAL NOTES ON 



mere expansions or flattened aggregates of cells, and others are 

 mere strings of cells, which, by fasciation, can easily become 

 expansions. They issue from a disk or cellular basis, by which 

 the plant is attached to other bodies. Out of this basis, as if from 

 a placenta, common to both leaves and roots, we see the so-called 

 roots evolving. In some, these beginnings of roots remain as 

 simple nipples ; in others, they grow into longer roots, until we 

 find whole masses of roots like mops. 



In the rhizome of seaweeds, as if from a common lengthened 

 placenta, we find roots at intervals exactly as we do in ferns and 

 phaenogams. In Sargassum, lacerifolium^ we have adumbrations 

 of some of the higher land plants, both in foliage and fructifi- 

 cation. 



In Macrocystis pyrifera^ we get adumbrations of our Cycads 

 and Palms. Some seaweeds develop tendrils as in land plants. 



If we compare two very distinct plants which are placed by 

 systematists at a great distance from each other, we find that, on 

 close analysis, they differ very little from a morphological point of 

 view. Monarda didyma, at the apex of the stem, has a whorl of 

 leaves, then a whorl of involucral bracts, within that a whorl 

 or whorls of flowers, and in the centre of all the continuation of 

 the stem with a repetition of the flower head.f 



Now in the horsetail we have a stem, then at each node a 

 leaf -sheath, out of which another stem projects, and then another 

 sheath and another stem, and so on, till the apex develops a 



* " Harvey's Phycologia Austr.," v. 4, pi. 208. 



f " Harvey's Phyc. Austr.," v. 4, p. 202. This seaweed has an immense 

 range, from Cape Horn to California, according to Darwin and Hooker. Its 

 stem does not appear to be a carrier of nourishment from the roots, at least 

 to any extent, for Ch. Darwin, in his " Voyage in the Beagle," says : Its stem 

 seldom has a diameter as much as an inch, yet it can grow from a depth of 

 45 fathoms to the surface and spread itself many fathoms on the surface. 

 It must be largely fed by the surrounding medium through the cells of its 

 frond. He adds, the immense quantities of it act as natural breakwaters, and 

 that the number of living creatures whose existence depends on this kelp 

 is wonderful. Numbers are attached to the frond, and on shaking the 

 tangled roots a pile of all sorts of animals falls out. — (" Darwin's Voy.," 

 p. 255, new edit.) 



X The drawing shown in " Nicholson's Diet, of Gardening " does not show 

 the continuation of the stem. 



