Mr. H. O. Sicphens on Palmclla prodigiosa. 411 



matter or flour-paste, or substances rich in nitrogen, a vivid red 

 may be induced ; if rice-paste or feebly uitrogenized matters, the 

 colour may tend to blue or violet. But this is at present only 

 conjecture. 



Concerning the place in the organic kingdom to which this pro- 

 duction ought to be referred, I am of Dr. Montagne's opinion, 

 that it is an Alga, belonging to the Nostockineee, differing from 

 Protococcus in wanting the pellucid margin to the globes, and 

 from Hamatococeus, which is furnished with several pellucid 

 rings to each cell, and in which the aggregate granules or cells 

 form a frustulose crust, the frond of the Blood Rain being de- 

 cidedly gelatinous. 



In my judgement this plant is a Palmella closely allied to 

 P. cruenta, but certainly distinct, the cells or granules of the 

 latter differing from it not only in their colour but size, being 

 very much smaller than those of P. prodigiosa. 



The mode by which the Blood Rain propagates is extremely 

 curious (as Mr. Berkeley also noticed) ; it seems to extend itself 

 by elastically spirting a sort of jet or column of red particles, 

 which iMr. B., in a letter, aptly compared to a jet of blood from 

 an artery, and by this mode of propagation, I think, the extra- 

 ordinary rapidity with which a large surface becomes covered 

 with the Alga can be satisfactorily explained. 



A portion of paste covered with the Blood Rain was dried in 

 an oven for forty-eight hours until nearly baked into biscuit, vet 

 fragments of this exsiccated Alga readily grew^ when scattered 

 on fresh-made dough. 



The vitality of the cells of this Palmella, like the ova of some 

 fishes, insects, and many other animals of lower grade, is not 

 impaired (within a certain time) by exsiccation even at a high 

 temperature, and when dry retain their germinating powers for 

 a very considerable period, and are disseminated by currents of 

 air and other methods. 



Thus the unexpected appearance of this very conspicuous and 

 somewhat portentous-looking production in singular situations 

 and circumstances, can be explained without resorting to far- 

 fetched reasonings or unphilosophical assumptions. 



EXPLANATION OF PLATE XVIL 



Fig. \. a, Palmella prodigiosa, Mont, (natural size), on beef; b, perpendi- 

 cular section ; c, portion of gelatinous frond, magnified ; d, cells 

 ditto ; eee, fibres of beef stained red by the colouring matter of 

 the Alga. 



Fig. 2. a, Palmella prodigiosa on flour-paste, natural size ; h, cells highly 

 magnified, some ruptured ; c, cells with films of mucus acted on 

 by iodine and sulphuric acid. 



Bristol, Dighton Street, Oct. 4th, 1853. 



