116 
palmellacej:. 
Order XIII.* — PALMELLACEiE. 
Palmellacece, Harv. Man. Ed. 2, p. 234. Palmellece , Dne. Class, p. 31. Endl. 
3rd. Supp. p. 10. Kutz. Phyc. Gen. p. 166. Hass. Brit. Fr. Wat. Alg. p. 306. 
Lindl. Veg. King. p. 18. Kutz. Bp. Alg. p. 196. Berk. Crypt. Bot.p. 114. Thwaites, 
in An. Nat. Hist. 2nd Ser. vol. 2, p. 312, and vol. 3, p. 243. Part of TJlvacece, Harv. 
Man. Ed. 1, p. 169* Part of Nostochinece, Ag. Syst. p. 13. Harv. in Hook. Br. 
fl- 2,p. 394. 
Diagnosis. Green or red, orange or yellowish, fresh-water Algte, composed of separate 
or aggregated (hut not united) globose or ellipsoidal cells, free, or lying in a gelatinous 
matrix ; sometimes stipitate. Propagation by division of the endochrome. 
Natural character. The plants of this family are the simplest in organization of 
any of the great class of the Algae, and therefore fall to the lowest point of the scale in 
the arrangement we have adopted. In them we no longer find any distinction of root 
from frond ; most of them are amorphous masses of gelatinous substance, and only in a 
few, as in Hydrurus, does the gelatine assume a tolerably definite form, and display 
itself as a branching frond. The simplest of the group (Protococcus) consists of single, 
isolated cells, strewn on the surface of the soil or of whatever object to which they 
happen to attach themselves. These cells are globose or egg-shaped, have a hyaline, 
often gelatinous coat, and contain a utricle filled with dense endochrome of various 
colours ; sometimes green, but often red or orange. Of this character is the Red Snow 
plant (Protococcus nivalis ) which has attracted so much notice, from the accounts of 
arctic travellers, and which may often be seen tinging the snows of Mount Blanc and 
other snowy Alps with a pale roseate hue. The mode of propagation of this primordial 
plant is as simple as its structure. The matter in the cell becomes condensed at 
maturity, and then subdivides into 4, 8, 16, or more parts, on a quaternary scale of 
increase ; each frustule acquires a new cell-coat while yet within the parent cell, and 
when the process is completed, and all the endochrome of the mother cell has thus been 
used up in providing for the progeny, the cell-coat bursts and a multitude of minute 
cell-plants, similar in all respects to the parent except in size, are launched into the 
world. These grow till they attain the dimensions of the parent, when a similar cell 
division takes place ; and thus in a very few generations millions of new plants may 
be produced from a few or even from a solitary original. As the process of growth and 
* Orders XI. Desmidiacece , and XII. Diatomacece are omitted in this work ; the American species having 
been already partially described and published by Professor Bailey, and the author not being supplied with 
any new materials for publication. 
