265 



subside. Their specific gravity must be very low, and this, aided by their gyra- 

 tions, will account for the extensive and, when aided by air-currents, rapid 

 diffusion of Elvellaceous sporidia. 



ON A SINGULAR FORM OF SPIRILLUM 



J E N N E R l—Hass. 

 [By Rev. J. E. VizE, M.A., F.E.M.S., "Vicar of Forden— Read October, 1880.] 



In the month of June of the present year, a friend was staying with me whose 

 name in connection with Algw is well kno\vn. I mean Mr. Wills, of Wylde 

 Green. We visited a few of the pools in Powis Castle Park, and in the pool 

 situated the nearest of all to the castle entrance, and facing south-west of the 

 castle, we found some freshwater Algce. Spirillum Jenneri was one of these. 

 Spirillum,, I may say, is a genus closely allied to oscillitoriw. The whole family 

 is oscUlatoriacece, and has very wonderful movements. When seen under a micro- 

 scope, there is a constant motion going on. They oscillate, move stealthily along, 

 or in a snake-like movement, the rapidity of their growth being almost as striking 

 as their movement. The Spirillum we found, as I believe is always the case, was 

 mixed up with a considerably predominating quantity of oscillatoria — a set of 

 plants easily distinguished from Spirillum by the thread-like filaments being 

 straight instead of spiral. Nearly all the filaments were single, but there were 

 instances, here and there, in which two of these filaments had interlaced ; and to 

 see them working together was amongst the most wonderful sights I ever witnessed. 

 Do justice to it I could not. Nevertheless, it would not be right to refuse to give 

 any idea about it, imperfect though it must be. Suppose two very long snakes or 

 screws of two corkscrews, the coils of which were for a very great distance indeed 

 the same diameter — imagine that these two serpentine things progressed most 

 elegantly backwards and forwards in the water, for they are never still, although 

 their movement is slow and deliberate, and I should think uniform as to their 

 number per hour. Let two approach each other so exactly that they just hit the 

 right place for one to descend whilst the other ascends the coil. In this case you 

 get the double twist, and very superb is the sight. The filaments are fine as to 

 size, and dehcate as to colour, which is a light green. For a time this descending 

 of the one coil whilst the other ascended would go on. Presently there would be 

 a stoppage of motion, and the very reverse progress would commence. The 

 originally upward coil would be the downward now, and the downward the up- 

 ward. This would be reversed again in due course of time, and the changes again 

 and again occur. It may be well to say that these double forms appeared to be 

 confined to one special spot in the material from which the specimens were 

 obtained from the mass of oscillatoria, and I fancied there was in that spot a 

 slightly altered tint of colour. 



V 



