766 ALG. 
Sub-order 5. Volvocineex (fig. 1127). Henfrey diagnoses them 
as follows :—‘ Microscopic bodies swimming in fresh water 
by the aid of cilia arranged in pairs 
Fig. 1127, upon the surface of a common semi- 
gelatinous envelope, the pairs of cilia 
each belonging to a green corpuscle re- 
sembling the zoospore of a confervoid, 
imbedded in the periphery of the com- 
mon envelope. Reproduction by the 
development of each corpuscle into a 
new colony, the whole being set free 
by the solution of the parent envelope, 
or by conversion of the corpuscles into 
Fig. 1127. The Revolving encysted resting-spores like those of 
Sani 
wie 
AY, 
é var, 
ay 
ra 
Ke} 
SOLS 
Volvox ( Volvox globator’). ae . 
The outer surface is cili- Confervee ee: sexually, by Pat sabe = cal 
ated. tion taking place within the colony from 
oogonia and antheridia.’ Illustrative 
Genera:—Volvox, Lam.; Gonium, Lam. The members of 
this group were frequently regarded as Infusorial Animaleules, 
but in all their essential characters they closely resemble the 
Confervoidez ; indeed, they are commonly placed in that 
sub-order. 
Distribution and Numbers.—Alge are more or less distributed 
throughout the globe, growing in salt or fresh water, or in 
moist situations. Some species are found in the boiling springs 
of Iceland, &c.; others occur in mineral springs, and some in 
chemical solutions. The waters of whatever temperature have 
their own peculiar forms. It is impossible to estimate with any 
degree of accuracy the number of species of Algze, but they may 
be roughly estimated at 2,500. 
Properties and Uses.—Several species are employed for food 
in different parts of the world ; as, Laminaria saccharina, L. 
digitata, L. potatorwm, &c.; Alaria esculenta, Durvillea utilis, 
Sargassum species, Iridexa edulis, Chondrus crispus and C. 
mamillosus, Gelidiwm corneum, &c., Gigartina speciosa, Lawren- 
cia papillosa, &e., Gracilaria lichenoides and other Gracilarias, 
Rhodymenia palmata, Porphyra vulgaris, and P. laciniata, Ulva 
latissima, U. compressa, &c., Nostoc edule and other species, 
Hormosiphon arcticus, and many others The nutritious pro- 
perties of the above are due to the presence of starch, sugary 
matter (mannite), mucilage, and albumen. M. Payen also dis- 
covered a principle in Gelidiwm corneum (Algue de Java), and 
some other Algze, to which he gave the name of gelose. To this 
substance the nutritious properties of Algze are likewise, to a 
great extent, due. According to Payen, 1 part of gelose dis- 
solved in 500 parts of boiling water will afford, upon cooling, a 
colourless, transparent jelly,—thus forming ten times more jelly 
than a like weight of the best animal gelatine. In order, there- 
fore, to produce a jelly of equal consistency, it would be only 
