Royal Microscopical Society. 53 



III. — The Development of Phycocyan. 

 By Thomas Chaetees White, M.E.C.S., L.S.D. 



{Read hvfore the Royal Microscopical Society, Jan. 11, 1871.) 



Plate LXXV., Upper Part. 



There are many present, doubtless, this evening who may re- 

 member the interesting specimen of Dichroic Fluid exhibited upon 

 two occasions by our late esteemed President —one obtained at 

 Canterbury, by Mr. Sheppard, and the other by Mr. B. D. Jackson, 

 from a pond at St. Leonards ; these fluids, as you may remember, 

 presented the peculiarity of looking red by reflected light, and blue 

 by transmitted light. I do not know if either of these gentlemen 

 saw the process of development of this Dichroism, but I have had 

 the opportunity of watching its gradual growth, and desire in this 

 short communication to lay before you its life history as I observed 

 it, and then leave to others the explanation of its origin and the 

 theories deducible from it. 



About the early part of November, having some friends coming 

 to spend a microscopical evening, and being desirous of exhibiting 

 something living for their amusement, I sent to a favourite hunting 

 ground of mine, the Bound Pond in Kensington Gardens, where 

 often floating portions of Myriaphyllum and such-like aquatic plants 

 afford abundant game for the microscopist ; but, alas ! Boards of 

 Health, and such-like bodies, being inimical to everything but clean- 

 liness, had shot in plenty of clean gravel, and no weeds could be 

 detected : where Floscularia and Bacillaria had before been found in 

 plenty, nought could be gathered but some green flocculent matter, 

 which settled at the bottom of the collecting bottle hke green 

 cumuli clouds. Upon placing some of this under the microscope, 

 the green matter was seen to be made up of moniliform strings of 

 cells, coiled up to the extent of a turn and a half, and of a pale 

 green colour : mixed with these were several bundles of fibres of an 

 ochreous colour, looking like dead bundles of Bacillaria jparadoxa, 

 arranged in a slightly fan-shaped form (Fig. 2) : animal life appeared 

 almost absent, and was represented by a few monads. Not thinking 

 this worth exhibiting to my friends, I screwed down the top of my 

 York bottle, and stood it on the window-ledge inside my room, and 

 it was there forgotten for about a fortnight, when by chance look- 

 ing up at it, I saw that the green flocculent matter had descended 

 to the dead level of some yellowish-coloured mud, but for about a 

 quarter of an inch above it was a layer of the deepest richest indigo 

 blue I had ever seen. Taking it down carefully, so that no disturb- 

 ance of it should take place, I looked at it by reflected light, when 

 it was a rich crimson lake. I then remembered the Dichroic Fluids 



