410 Mr. H. 0. Stephens on Palmella prodigiosa. 



true Algoid, and with Dr. Montagne I refer it to the genus 

 Palmella, 



The history of the appearance of the Blood Rain is as follows : — 



I observed at table the under surface of a half-round of boiled 

 salt beef, cooked the day before, to be specked with several bright 

 carmine-coloured spots, as if the dish in which the meat was 

 placed had contained minute portions of red-currant jelly. Sus- 

 pecting what these might turn out to be, I directed the beef to 

 be placed aside. On examination the next day, the spots had 

 spread into patches of a vivid carmine-red stratum of two or 

 more inches in length. 



With a simple lens the plant appears to consist of a gelatinous 

 substratum of a paler red, bearing an upper layer of a vivid red 

 hue, having an uneven or papillated surface. 



The microscope shows this stratum to consist of generally 

 globose cells immersed in or connected by mucilaginous or gela- 

 tinous matter. 



The cells vary in size, and contain red endochrome. As far as 

 I can observe, they consist of a single cell-membrane and con- 

 tain a nucleus. Treated with sulpho-iodine they become blue. 



Mr. Berkeley writes me, " This plant is sometimes of a blue 

 colour, and at other times the cells are colourless." I have seen 

 the cells very pale or nearly colourless, but not blue. Perhaps 

 the colour of this Alga may be dependent on the matrix on 

 which it may chance to grow ; and to this I shall again presently 

 refer. 



A portion of the beef with the Palmella was dried in an oven 

 for several hours, in order to prevent decomposition, and sent to 

 Mr. Berkeley; this rapidly germinated when placed on a paste 

 of rice-flour, and from these the observations recorded in the 

 Gardeners' Chronicle were made. 



I placed a few fragments of the Alga on a paste of wheat- flour : 

 in twenty-fovu* hours these minute fragmentary specks grew to 

 spots the size of sixpences, and in forty-eight hours the paste 

 was nearly covered by a layer of blood-red matter, as represented 

 in one of the drawings. 



It is stated, that the colour of this Alga is very permanent, 

 and that it dyes silk bright red ; this is, I think, corroborated 

 by the fact, that the fibres of the beef on which it first appeared 

 were permeated with the colouring matter of the Alga (PI. XVII. 

 fig. 1. e e e). 



I noticed, when sown on rice-paste, the Palmella assumed a 

 violet hue, confirming Mr. Berkeley's observation that the cells 

 arc sometimes blue (PI. XVII. fig. 2. b). 



Perhaps the colour of the plant may much depend on the 

 chemical elements of the matrix : if that happens to be animal 



