. A manual of zoology for the use of students : with a general introduction on the principles of zoology . Zoology. CCELENTERATA: HYDROZOA. 87 In certain Corynida, however, we meet with a still higher form of structure, the gonophores being now said to be " ; In these cases the generative bud is primitively a simple sacâsuch as the " sporosac "âbut ultimately devel- ops itself into â a much more complicated structure. The gonophore (fig. 13, <r) is now found to be composed of a bell- shaped disc, termed the " gonocalyx," which is attached by its base t
. A manual of zoology for the use of students : with a general introduction on the principles of zoology . Zoology. CCELENTERATA: HYDROZOA. 87 In certain Corynida, however, we meet with a still higher form of structure, the gonophores being now said to be " ; In these cases the generative bud is primitively a simple sacâsuch as the " sporosac "âbut ultimately devel- ops itself into â a much more complicated structure. The gonophore (fig. 13, <r) is now found to be composed of a bell- shaped disc, termed the " gonocalyx," which is attached by its base to the parent organism (the trophosome), and has its cavity turned outwards. â From the roof of the gonocalyx, like the clapper of a bell, there depends a peduncle or " manubrium," which contains a process of the somatic cavity. The manubrium gives out at its fixed or. proximal end four prolongations of its cavity, in the form of radiating lateral tubes, which run to the margin of the bell, where they com- municate with one another by means of a single circular canal which surrounds the mouth of the bell. This system of tubes constitutes what is known as the system of the " gonocalycine ; The gonophore, thus constituted, may remain per- manently attached to the parent organism, as in Tubularia indivisa (fig. 14, c); but in other cases still further changes ensue. In the higher forms of development (fig. 14, rf) -the. Fig. 14.âReproductive processes of Hydrozoa. d Sporosac ; h Disguised medusoid ; c Attached medusiform gonophore ; d Free medusiform gonophore. The cross shad- ing indicates the rejproductive organs, ovaria or spermaria. The part completely blaclc indicates the cavity of the manubrium and the gonocalycine canals. manubrium acquires a mouth at its free or distal extremity, and the gonocalyx becomes detached from the parent. The gonophore is now free, and behaves in every respect as an independent being. The gonocalyx is provided with m
Size: 2745px × 911px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorni, bookcentury1800, bookdecade1870, booksubjectzoology
