General principles of zoology . IVIDUALS OF THESAME SPECIES. Colony Formation.—Colony and state formation areconditions which exist between individuals of the samespecies. By an animal colony is understood a union of (ECOLOGY. I99 numerous individual animals which depends upon an organicbodily connection; the latter may arise in two ways: first,by animals originally separate approaching one another andpartially fusing together; secondly, by animals formed bydivision and budding remaining united with one anotherinstead of separating. The first case is extremely rare, andin the animal kingdom pl
General principles of zoology . IVIDUALS OF THESAME SPECIES. Colony Formation.—Colony and state formation areconditions which exist between individuals of the samespecies. By an animal colony is understood a union of (ECOLOGY. I99 numerous individual animals which depends upon an organicbodily connection; the latter may arise in two ways: first,by animals originally separate approaching one another andpartially fusing together; secondly, by animals formed bydivision and budding remaining united with one anotherinstead of separating. The first case is extremely rare, andin the animal kingdom plays no role \vhatever. Colony Formation by Fusion.—Many protozoa fusewith one another and form larger bodies in which the indi-vidual animals can still be recognized. Among the multi-cellular animals, that of Diplozoon paradoxum is the onlycase known where animals (Diporpa) normally two (), sprung from different eggs, unite into a double animal—which recalls certain double monsters, as for example theSiamese FIG. 105.—Development of Diplozoon paradoxum. (From Boas ) (i) Larva, from whichcomes (2) Diporpa. (3) Two Diporpse uniting. (4) The Diporpse have united intoDiplozoon. ;«, mouth ; d, digestive tract ; Si, posterior clasping apparatus ; t>, ventralsucking-disk, which serves for attachment to the dorsal cone, r. Colony Formation by Incomplete Division and Bud-ding.—In general it can be said that the important in-stances of colony building occurring in nature rest uponincomplete division or budding. An animal has the powerof asexual multiplication; but this does not go on tothe normal conclusion, since complete separation is notaccomplished, though indeed two or more individuals areformed. There persist more or less extensive bridges oftissue, which unite the divided parts with one another,or the buds with the mother. The marine colonies ofcorak and Iiydroids (Fig. 88) may consist of thousands ofindividuals which, by repeated incomplete budding or
Size: 2736px × 913px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
