PALMELLACE^E. 13 



boiled vegetables, or even decaying Agarics, is quite astonishing, making 

 them appear as if spotted with arterial blood ; and what increases the 

 illusion is, that there are little detached specks, exactly as if they had 

 been squirted in jets from a small artery. The particles of which the 

 substance is composed have an active molecular motion, but the mor- 

 phosis of the production has not yet been properly observed, and till 

 that is the case it will be impossible to assign its place rightly in the 

 vegetable world. Its resemblance to the gelatinous specks which occur 

 on mouldy paste, or raw meat in an incipient state of decomposition, 

 satisfy me that it is not properly an Alga." Mr. H. O. Stephens, on 

 the other hand, contends that it is an Algoid production. After nar- 

 rating its history (see "Ann. Nat. Hist.," 1853, p. 409), he says "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 con- 

 tained minute portions of red currant jelly. 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 sub- 

 stratum of a paler red, bearing an upper layer of a vivid red hue, hav- 

 ing an uneven or papillate surface. The microscope shows this stratum 

 to consist of generally globose cells immersed in or connected by muci- 

 laginous or gelatinous matter. The cells vary in size, and contain red 

 endochrome. As far as I can observe they consist of a single cell- 

 membrane, and contain a nucleus. Treated with sulpho-iodine, they 

 become blue. In my judgment 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." The memoir also 

 contains observations on the great vitality of this species, and other 

 subjects connected therewith, to which the student is referred. 



Plate V.fig. 5. a, part of thallus, magnified 400 diam. ; b, portion 

 magnified 800 diam. 



GENUS 7. PORPHYRIDIUM. Nag. (1849.) 

 Thallus between gelatinous and membranaceous, somewhat 

 incrusting, long and broadly expanded, composed of globose or 

 many-sided cells. Multiplication of the cells by alternate di- 

 vision in all directions. Propagation unknown. 



This genus is placed by some authors in Porpliyracece, near the genus 

 Pangia, in the class Rhodophycece (see Rabh. Alg. iii. 397), but we prefer 

 to retain it near the old genus Palmella, in whicb it was previously in- 

 cluded, and to which it seems to be most naturally allied. 



Porphyridium cruentum. Nag. Einz. Alg. t. 4 H. 



Thallus dark purplish-red, gelatinous ; cells angular or 

 rounded. 



SIZE. -007--01 mm. (Rabh.), -0965--009 mm. (Kirch.). 



Kirch. Alg. Schl. p. 111. Rabh. Alg. iii. 397. 



Palmella cruenta, Ag. Syst. p. 15. Kabh. Exs. No. 14 and 

 1071. Hass. Alg. p. 308, t. 80, f. 5. 



Tremella cruenta, Eng. Bot. t. 1800. Grev. Sc. Crypt. Fl. 

 pi. 205. 



On the naked ground, moist walls, &c. Common throughout 

 Europe. 



