OSCILLATORIACEJE. 221 



the same time propelled forward ; and as the oscillation con- 

 tinues after the filament has left its nest, the little swimmer 

 gradually moves along, till it not only reaches the edge of the 

 vessel, but often as if in the attempt to escape confinement 

 continues its voyage up the sides, till it is stopped by dry- 

 ness. Thus in a very short time a small piece of Oscillatoria 

 will spread itself over a large vessel of water. I am not aware 

 that the filaments ever return to the stratum after they have 

 once left it: their course is ever "ahead," which looks 

 more as if they were obeying some condition imposed on them 

 than if their movements were spontaneous, like those of ani- 

 malcules. There is indeed a wide difference between the 

 calm, undeviating onward course of these singular vegetables 

 and the wild and wayward wanderings and contests of ani- 

 malcules, as seen in the field of an oxy-hydrogen microscope. 

 But such difference, though it may afford probability of a 

 difference in the nature of the life enjoyed by the two entities 

 under review, by no means proves this difference ; for we 

 must remember that there are animals as inert, and apparently 

 as passionless, as our Oscillatoria. And let not the undevi- 

 atingly onward course be assigned to vegetables solely, for if 

 animals (some at least) were always sane, their course would 

 be, like that of the Oscillatoria, still onward, seeking an 

 " Excelsior " which is ever in advance of their position. Se- 

 riously, I am unable to explain satisfactorily the movement 

 of these vegetables, for vegetables, and not animals, I be- 

 lieve them to be, and 1 have no wish to theorize on the 

 subject. Our knowledge is yet far from sufficient to allow of 

 our dogmatizing on this point : our maxim must still be, 

 observe. 



SYNOPSIS OF THE BRITISH (MARINE) GENERA. 



I. RIVULARIA. Filaments radiating from a point, immersed 



in firmly gelatinous, globose or lobed fronds, of defi- 

 nite shape. [Plate 26, A.] 



II. SCHIZOTHRIX. Filaments rigid, in branching bundles, 



at length splitting. [Plate 26, B.] 



III. CALOTHRIX. Filaments short, tufted, fixed by their 

 base only. [Plate 26, C.] 



IV. LYNGBYA. Filaments elongate, decumbent, flaccid. 

 [Plate 26, E.] 



