'§»^44,45. 



THE POLYPI. 



51 



and especially the nature of the soil upon which the colony may have been 

 fixed."^ tsj 



§ 44. 



3. It is probable that all Polyps reproduce by eggs. This requires two 

 kinds of organs, one to produce the egg, the other the semen. Both kinds, 

 ovary and testicle, have already been described in many species. 



Their distribution is quite varied. In some, the sexes are united in the 

 same individual, '" in others they are distinct ;'-' with the colonial polj-ps 

 the sexes are separate, and each colony'"' maj^ be composed of individuals 

 which arc androgynous, or those of one sex alone. '^' 



Some species are sexless, and remain so ; but ihey produce by gemmation 

 individuals of a particular character, which have sexual organs.*^' These 

 last, which have usually either a campanulate or discoid form, are separated 

 from the corallum often before the sexual organs have been formed, and 

 which they do not acquii'e until an advanced period of their lives. During 

 this time they swim freely about, like the pulmograde Acalephae,'^' for 

 which, as well as for young Polyps, they are often taken. ^''^ 



§45. 



That the relations just described really exist, may be learned from the 

 following facts : In Coryne echinataund vulgaris, there are formed at their 

 base, quadrangular and campanulate individuals, which lay numerous 

 eggs."' In like manner also, ovigerous capsules are formed about the base 

 of Syncoryne ramosaJ'-' In Ccryiie fritillaria,'-"- the new individuals are 

 completely detached and swim freely about, closely resembling Medusae. 

 In this condition they are developed, and their eggs come to maturity. <^^ 



3 Efscliara and Ftustra have a lamellated foiin 

 when ft.\ed to stone.-;, sliells, or the broad leaves of 

 Algae ; but are tutuilar when attached to the 

 stems of plants. Alcyonella stagnorum under- 

 goes similar changes in the form of its coi'allmn. 

 It divides in a regular dichotomous manner 

 {Eichhorn, Beitr. zur Naturgesch. d. klehisten 

 Thiere.Taf.IV.; als;) iioese/, Ijc. cit. Taf. LXXIII. 

 and LXXIV.), and in this form has been described 

 under the name of Plumatella campanulata by 

 Lawarck. But when a colony of these Polyps 

 is fixed upon a stone or a sunken root, they com- 

 mence to be developed in a dichotomous manner. 

 But afterwards they become lapidescent by the 

 branches of Ijoth modes interlacing each other. As 

 the mass becomes more voluminous and dense, the 

 tubes of the dead generation support those of the 

 living. (See Lamouroiix, E.'cposit. mtthod. des 

 Genres de I'ordre des Polypiers, PI. LXXVI. fig. 

 5.) L'nder this form this Polyp has received the 

 name of Alcyonella utognorum (see Raspail, 

 Hist. Nat. de I'Alcyonelle fluviatiie).t 



1 Hydra. 



2 Actinia-X 



3 Alcyonella. 



* [End of § 43.] For a fuD account of the 

 reproductive process with Polyps, and the most 

 philosophical exposition of the relations of gem- 

 mation and its analogies and affinities with other 

 developmental processes, see Dana, loc. cit. p. 85. 

 No abstract can be given of such a work. — Ed. 



t [§43, note 3., For full details of the gemmi- 

 parous mode of reproduction with the Bryozoa, 

 see Van Beneden (Uecherch. sur Torganis. des 



4 According to Erdl (_Froriep''s neuo Notizen, 

 1839, No. 249, p. 101) the coralla of I'eretillum 

 cynomorium and Alcyonium have alwajs either 

 male or female individuals aloue. Krolin has 

 Ijerceivcd the same of Sertularia {Muller^s Arch. 



1843, p. 181). 



5 Coryne, Syncoryne and Campanularia. 

 C Coryne and Campanularia. 



7 A"ery striking, at least, is the resemblance of 

 Van Benede7i''s (M6m. loc. cit. pi. II.) figure of a 

 free female of Campanularia gelatinosa and those 

 of Sam (Beskrivelser. loc. cit. p. 28, Taf. VI. fig. 

 14) of small Acalephae, named by him Cytaeis 

 octopunctata, and by Will (Horae tergestiuae, 



1844, p. 68, Taf. II. fig. 5) as Cytaeis polystyla. 

 1 R. Wasner. Isis, 1833, p. 256, Taf. XI.; also 



Icones zoot. Tab. XXXIV. fig. 16. 



^ Lowen. }Viesmann\i Archiv. 1837, I. p. 321, 

 Taf. VI. fig. 19-25. 



3 Steenstrup. Uebcr d. Generationswechsel, p. 

 20, Taf. I. fig. 41-47. 



4 According to Sars (Beskrivelser. loc. cit. p. 6, 

 Taf. I. fig. 3), these remarks are also true of Co- 

 rymorpha nutans. 



Laguncula, &c., Mem. Acad. Koyale de Bruxelles, 

 XVIII. ; also, Recherch. stu" I'Anat. la Physiol, 

 et le dtveloppement des Eryozoau-es, &c. Ibid. 

 XIX.). Sse also Allman, Report Brit. Assoc. 1850, 

 p. 320. — Ed. 



J f § 44, note 2.] According to my own obser- 

 vations, the Actiniae have bath individuals which 

 are hermai)hrodites and those of one sex alone. 

 — Ed. 



