Page:The New International Encyclopædia 1st ed. v. 01.djvu/402

ALGÆ. is called Ccenoeyte ( q.v. ). Another interesting genus is Botrydium, which has the form of a green, swollen bladder about the size of a pin- head, and is attached to moist soil by a system of branching root-like filaments. Botrydium and Vaucheria are practically the only terrestrial or fresh water representatives of this order. The Charales form the highest group of the Chlorophyceae in respect to vegetative structure. The forms are remarkable for the synnnetry of their parts, a condition which results from a well-defined method and order of growth. Tlie growth is dominated by a terminal cell, whose di- visions determine with matliematical regularity the position and structure of the nodes (joints) and internodes. The system of growth is even followed in the development of the leaf-like branches, ordinary branches, and in the develop- ment of the female sex organ (oiigonium). The sexual organs are complex, especially the male organ (antheridium), which develops thousands of sperms. The eggs are large and are protected by a set of enveloping filaments, the whole con- stituting a complex female organ.

Pn.isOPHYCE.TS. The Brown Algfe also form a very large group, which contains diverse lines of development, the forms ranging from simple filaments to the gigantic Kelp or Devil's Apron (q.v.), and highly specialized rock weeds. This class also presents excellent illustrations of the principal stages in the evolution of sex. There are two sub-classes : the Pha?osporefE, whose reproductive cells, whether sexual or asexual, are swimming spores, and the Cyclo- sporefe, whose reproductive cells aie large eggs fertilized by highly specialized sperms. The motile reproductive cells of the group, whether sexless spores or gametes (sexual cells), are peculiar in being bean- or kidney-shaped, with the pair of cilia inserted laterally. There are a dozen or more orders in this group, the largest being the Eetocarpales, comprising some of the simplest filamentous forms; the Laminariales or kelps, and the Fueales, which include the rock weeds and Sargassum. In vegetative complexity some of the Fueales are probably the highest of all the Algie. For illustration see Ph.isgpjiyce.e. Rhouophyce^. The Red Algfe are acknowledged to be the most beautiful of all the Algae, because of the delicacy of their structure and brilliancy of color. The vegetative structure is not so highly differentiated as in some of the Brown and (Jreen Alga?, but the method of sex- ual reproduction is especially complex. As the result of the fertilization of the female cell by the fusion of a sperm with the Trichogyne (a hair-like process of the female cell, q.v.), there arises a growth of filaments constituting a new generation (sporophyte), which remains at- tached to the parent plant. The filaments of this sporophyte sometimes establish secondary con- nections with the sexual plant (gametophyte) for purposes of nutrition. Certain cells of the sporophyte become spores (carpospores) . The masses of spores constitute the fruit, called a cystocarp, which frequently includes a highly developed receptacle formed from the tissue of the parent plant. The sperms of the Red Algae are non-motile. There. is an asexual method of reproduction by tetraspores, so called because they are generally formed in the mother-cell in groups of four. For illustration see HyokoI'iivtes. The Alga; furnish especially good illustrations of some biological phenomena of general interest. Perhaps the most remarkable are the physiologi- cal conditions surroimding the development of the reproductive cells. The commonest form of reproductive cell is the swimming spore, which became established very early in the develop- ment of the Algoe, as far back as the Proto- coccales, whose members frequently pass a con- siderable part of their life history in a motile condition, essentiallj- like that of a swimming spore. Whenever a higher alga develops swim- ming spores, which generally happens at a cer- tain period of its life history, it may be said to return to one of the conditions of its early ancestors. As has been mentioned before, the simple motile sex cells (gametes) which fuse in pairs in the water are unquestionablj' swim- ming spores endowed with sexual qualities, or, stated differently, lacking the power to develop independently into new plants. It has been thor- oughly established by many experimental studies that these peculiarities are determined by envi- ronmental factors. As an example, almost all Hydrodictyon plants will produce sex cells after cultivation in a solution of cane sugar and under subdued light. Asexual spores will be devel- oped by the same plants when cultivated in a nutrient salt solution with bright illumination. As would be expected in a group where sex begins, there are a great many illustrations of partheno- genesis among the Algae: that is, sex cells very frequently develop new plants asexually ( without fusing). There are instances of parthenogenesis in almost all large groups of the Algae, and the phenomenon is frequently related to seasonal and other environmental conditions. See.

The AlgiE, as a whole, must be considered as a complex of divergent lines of development, very few of the living tj'pes being near the theoretical main line of ascent to the Bryophytes (liverworts and mosses). The various lines have frequently worked out similar vegetative conditions, and, what is most interesting, several groups have arrived independently at the same condition of sexual differentiation. For illus- trations, see articles Chlorophtce.?; ; CyaNOPHYCE.E ; PlLEOPHYCE.*;, and Rhodophtcbls).

For general description of Algie, consult: Eng- ler and Prantl, Die natilrlichcn I'^Uinzenfamilien (Berlin, 1899, et seq.) ; Murray, Introduction to the Htudy of Seaweeds (Londou, 189.5) : Far- low, .I/dcijip Alffw of Neiv Utii/land (Salem, 1881) ; Cook, British Fresh ^yater Algw (London, 1881- 83) ; Kirchner, "Kryptogamen-flora von Schle- sien," in Schlesische Oesellschaft fur vaterliind- ische Kiiltiir (Breslau, 1870-89).

ALGARDI, al-giir'de, Alessandeo (1602-54). A prominent Italian sculptor and architect of the Baroque period. He was born at Bologna, where he first studied painting under the Carracci, but afterwards took up sculpture with Conventui. His style, however, was modelled upon Bernini's works at Rome, which was the principal seat of his activity. Like other sculptors of the Baroque style, of which he was, next to Bernini, the most prominent representative in Italy, he conceived sculpture iu a pictorial sense. Though his works are of high tetlinical ability, their effect is marred by a hollow pathos and exaggerated dramatic action. The most important are Saint Philip Ncri in Bologna, the tomb of Leo XL in Saint Peter's, Rome, iind (in the same church) the largest alto-rilievo in the world, representing the retreat of Attila from