OSCILLATORIACE^. 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 suflicient 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.] 



