702 



neither will,any instructed naturalist express a doubt as to the analogy 

 between endogens and articulates. These analogies have been so fully 

 established by more able pens than mine, that I could not attempt to 

 adduce new proofs without obvious impertinence, neither could I 

 retrace the steps of my predecessors without needless repetition. The 

 case is howes'er somewhat different in what are called the lower classes, 

 for we have until lately been taught to combine under the name of 

 acrogens, two totally dissimilar and distinct classes : one of these, acro- 

 gens is composed of the ferns, Lycopodia and mosses ; the other, thal- 

 logens, of the Fungi, Lichens and Algae. Now the thallogens are 

 very evidently analogous to the radiates, many of them display all 

 the peculiarities' of the radiate structure, and in those instances in 

 which the radiation from a centre is lost, analogues occur in the cor- 

 responding group from which this peculiarity is also absent. It must 

 however be observed that our knowledge of both classes is yet in its 

 infancy. Concerning the more conspicuous thallogens, the agarics, 

 an opinion has just been broached that they are merely the 

 flower of a subterranean plant,* and concerning one of our most inte- 

 resting zoophytal radiates, Photocrinus europaeus, it has been dis- 

 covered by Mr. J. V. Thompson, that its head, or armed disk, at a certain 

 period of its existence, becomes detached, and thenceforth wanders free 

 as Comatula rosacea. The question must occur to every reflecting 

 mind, — Are we to consider the Photocrinus or the Comatula the type 

 for comparison ? Is the spawn or the mushroom the perfect plant ? 

 These questions are not to be answered hastily. How little do we 

 yet know of the laws which regulate the reproduction of species ! 

 It was long a received opinion, that an animal or a plant repro- 



* After describing the hymenium, the pileus, &c., A. de Jiissieu says, "The 

 parts just described do not, however, constitute the whole of the fungus : they are, in 

 fact, in a certain sense, nothing more than its inflorescence. Before this is developed, 

 we see a number of filaments, radiating from a common centre (which centre is pro- 

 bably a spore in a state of geriniuation), and intersecting each other in all directions ; 

 they subsequently become entangled and thickened at certain points, at which are 

 formed the organs previously described. This filamentous net-work is named the 

 mycelium ; it is generally concealed below the surface of the ground, and escapes ob- 

 servation as well by its situation as by its fragile texture ; it is not however unfre- 

 quently developed in damp and dark places ; as, for instance, on w^ood in our cellars. 

 This mycelium is a sort of subterranean tree, which exposes to the light only the ex- 

 tremities of its branches, furnished with the organs of reproduction, so that in general, 

 all the fungi which we observe growing in communities, belong in reality but to a 

 sinole individual ; hence arises the circular disposition so frequently affected by them, 

 the mycelium being regularly developed in the centre, and sending its rays to equal 

 distances from that centre.'' — Botanique, par Adrien de Jussieu : p. 549. 



