Chap. I. 



METAMORniOSES OF ANIMALS. 



69 



treatise einln-acing the most recent investigations liaving as yet been published ; and 

 I mnst take it for granted, that before forming a definite opinion upon the com- 

 parisons instituted hereafter between the growth of animals, and the structural grada- 

 tion among fidl-grown animals, or the order of succession of the fossils characteristic 

 of different geological periods, the necessary information respecting these changes has 

 been gathered Ijy my readei's, and sufficiently mastered to enable them to deal with 

 it freely. 



The emlu'vology of Polypi has been very little studied tlius far; what we know 

 of the embryonic growth of these animals relates chiefly to the family of Actinoids.' 

 When the young is hatched, it has the form of a little club-shaped or pear-shaped 

 body, which soon assumes the appearance of the adult, from which it differs only by 

 having few tentacles. The mode of ramification and the multiplication by buds 

 have, however, been carefully and minutely studied in all the ftimilies of this class.^ 

 Acalephs present phenomena so peculiar, that they are discussed hereafter in a 

 special section. Their 3'oung^ are either pohq:)like or resemble more immediately 



See u]Rin this subject: — Leuckart, (Rcd.,) Ueber 

 den Polymorpliismus iler Individuen oder die 

 Ersdieinung der Arbeitstheilung in der Natur, 

 Giessen, 1851, 4to. — Reichert, (C. B.,) Die mono- 

 gene Fortpflanzung, Dorpat, 18.32. — IIlxley, (Tn. 

 H.,) Upon Animal Individualitj', Ann. and Mag. 

 Nat. Hist. 2d ser., 1852, vol. 9, p. 507. — Foubes, 

 (Ed.,) On the supposed Analogy between the Life 

 of an Indiviihial and the Duration of a Speeies, Ann. 

 and Mag. Nat. Hist., 2d ser., 1852, vol. 10, p. 50. 



— BitAUN, (Al.,) Das Individuum der Pflanze, q. a. 



— Betrachtungen iiber die Erscheinung der Ver- 

 jiingung in der Xatur, Freil)urg, 1849, 4to. fig. 



' Saus, (M.,) Beskrivelser og Jagttagelser over 

 nogle niaerkelige eller nye i Ilavet ved den Ber- 

 genske Kysf levende Dyr, etc., Bergen, 1835, 4to. 



— Fauna litloralis Norvegia', C'hristiania. ISlC, t\,\. 

 fig. — Ratiike, (H.,) in Burdach's I'hysiologie, \i>]. 

 2d, 2d edit. ]>. 215. — Zur Morphologie, Reisebemer- 

 kungen aus Taurien, Riga und Leipzig. 1837, 4to., 

 fig. — Agassiz, (L.,) Twelve Lectures, etc.. p. 40, 

 et seq. 



^ See Dana's Zoophytes, and Mii.XE-EnwAitDS 

 et Haime, Rccherchcs, etc., q. a. p. 31, note 2. 



* SiEBOLD, (C. Til. E. V.,) Beitriige zur Natur- 

 geschichtc der wirbelloscn Thicre, Dantzig. 1839, 



4to. p. 29. — LovEN, (S. L.) Beitrag zur Kenntniss 

 der Gattungcn Cainiianularia und Syncorj'ne, AViegm. 

 Arch., 1837, p. 249 and 321 ; French Ann. Se. n. 

 2de ser., vol. 15, p, 157. — Sars, (M.,) Beskrivelser, 

 q. a. — Fauna littoralis, q. a. — Nokdmann, (Al. v.,) 

 Sur les ehangements que I'age apporte dans la 

 maniere d'etre des Campanulaires, Comptes-Rendus, 

 1834, p. 709. — Steenstrcp, (.L,) Ueber den Gene- 

 rations- Wechsel oder die Fortpflanzung und Ent- 

 wickelung durch abwechselnde Generationen, Uebers, 

 ■von LouENZEN, Kopenh. 1842, 8vo., fig.; Engl, 

 by G. BiTSK, (Ray Society,) London, 1845, 8vo. — 

 VanBeneden, (P. J.,) Memoire sur les Campanu- 

 laires do la cote d'Ostende, etc., M6m. Ac. Brux. 



1843, vol. 17, 4to. fig. — Recherches sur I'Embry- 

 ■ogenie des Tubulaires, etc., Mem. Ac. Brux. 1844, 

 4to. fig. — DuJAUDiN, (Fi:i..,) Observations sur un 

 nouveau genre de Medusaires (Cladonema,) pro- 

 venant de la metamorphose des Syncorynes, Ann. Sc. 

 Ti. 2de ser. 1843, vol. 20, p. 370. — Memoire sur le 

 developprnicnt des Medusaires et des Polypes 

 Ilydiaires, Ann. Sc. n. 3e ser., 1845, vol. 4, p. 257. 

 — AViLL, (.L G. Fr.,) Hora; tergestimr, Leipzig, 



1844, 4to. fig. — Frey, (H.,) und Leuckart, (R.,) 

 lieitriige zur Kenntniss wirbelloser Thiere, Braun- 

 sdiweig, 1S47, Itii. fig. — Dai.yell, (Sir .J. G..) Rare 



