52 



THE POLYPI. 



§46. 



The Campanulariae and Sertvlariae prodncc at the end of their pedicle 

 and branches elongated sexless individuals. But in the angles of these 

 branches cells of another form, and containing many spherical individuals, 

 are developed. In these last sexual organs are formed, which, in Campari' 

 ularia genicidata, occurs without a sejjaration of the new individuals from 

 the corullum, while in Campanularia gelatinosa it is after detachment has 

 taken place.**' i 



§ 46. 



In the eggs of polyps both a germinative vesicle and dot may often be 

 seen. Frequently, however, both disappear at a very early period. The 

 envelopes of the egg are usually of a simple,'^* though sometimes of a 

 complicated structure. The spermatic particles are very active, and in 

 some species are filamentoid, in others composed of a solid body or head, 

 to which is appended a very delicate tail. Water does not appear to afiect 

 either their form or motion. *^> 



5 According to Krohn (Muller^s Arch. 1843, p. 

 174), it is probable that in Campanularia and Ser- 

 tularia both sexes are dcveloi)od iu this way. 

 From Ellis'' description of Campanularia dicho- 

 toma (Essai sur I'Hist. Nat. des Corallines, p. 

 116, pi. XXXVIII. fig. 3), it may be concluded 

 that the females, mistaken by these naturalists for 

 eggs, separate in this way from the coraUum. 

 Meyen (Nov. Act. physico-medica. XVI. Suppl. I. 

 18C4, p. 195, Tab. XXX. fig. 3, 4) has also taken 

 the medusoid females of this species for spawn. 



[Additional note to § 45.] The series of those 

 polyps, the sexless (nurse-like) individuals of 

 which produce self-dependent, medusa-like young, 

 has been increased by several more recent re- 

 searches. See Van Beneden, Recli. sur I'embryol. 

 d. Tubulaires, 1844, pi. I. IV. {Tiibularia and 

 Eudendrium) ; Sara, Faun, littoral. Norveg. p. 7, 

 Tab. I. (Podocoryna and Peri^onimus) ; Du- 

 jardin, Ann. d. Sc. Nat. IV, 1845, p. 257, pi. XIV. 

 XV. (various Ilydrina). It is true that the de- 

 velopment of the genital organs has not been ob- 

 served in these medusa-like individuals ; but they 

 have indeed in the medusiform individuals of Syn- 

 coryne ramosa and Coryne fritillaria, and there- 

 fore it may be proper to infer that the same is true 

 of other Hydrina and Sertularina. If it is cor- 

 rect to regard as the perfect state that in which 

 the individuals resemble Medusas, and as the im- 

 perfect state that in which they are polypoid, then 

 should we, as has been done already by many, re- 

 move these animals from the class of the Polypi, 

 and place them with the Acalephae.* 



1 In most Anthozoa. Eggs of this kind, belong- 

 ing to Actinia, Coryne and Veretillum, have 

 been figured by Wagner QVicgmann^s Arch. 

 1835, I. Taf. III. fig. 2 ; Prod. Hist. Gener. hom. 

 atque anim. Tab. I. fig. 1, and Icones zoot. Tab. 

 XXXIV. fig. 5, 17, 23). 



2 With most Bryozoa the spermatic particles 

 are filamentous. Both from theh- size and thcu- 



motions, they have been taken for parasites. 

 Kolliker (Beitr. zur Kennt. d. Gesehlechtsverhalt. 

 u. d. Saamtn. Fliissigkeit wirbellos. Thiere, p. 41, 

 Taf. II. fig. 17) has seen the spermatic particles of 

 a thread-like form, of Flustra carnosa, develop- 

 ing in cells, and has seen them moving in the cav- 

 ity of the body. I have seen similar ones in Crista- 

 tella mirabilis and Plumatella campannlata. 

 Those which were seen by Farre (Phil. Trans. 

 1837, p. 403, pi. XXIII. fig. 5, g) iu the cavity 

 of the body of Valckeria cuscuta, and were re- 

 garded by him as intestinal worms, have an oval 

 body, to which is attached a delicate tail. Nord- 

 mann (Faune Pontique loc. cit.) has found those of 

 Cellaria avicularia having the same form. Those 

 of Actinia have also a similar form (see Erdl 

 Muller's Arch. 1842, p. 301, and KiilUker, loc. 

 cit. p. 44, fig. 13). One should be careful and not 

 confound the spermatic particles with the nettling 

 organs having a similar form ; and especially as 

 the development of these last has apparently some 

 connection with that of the sexual organs (see 

 Erdl loc. cit. p. 305). According to Kul/iker, the 

 spermatic particles of Alcyonidium gelatinosum 

 have a lanceolate body, with a hair-like tail (loc. 

 cit. fig. 11). 



Spermatic particles of a cercaria-form have been 

 observed by Wagner (Icon. zoot. Tab. XXXXV. 

 fig. 7, 12) with Veretillum and Hydra ; by Van 

 Beneden (Rech. sur I'organisat. d. Laguncula, 

 and Rech. sur I'anat. d. Bryozoaires, pi. V. in the 

 Nouv. M6m. de Bruxelles, &c. XYIII.), with La- 

 guncula ^nd Halodactylus ; by Rathke {If'ieg- 

 mann's Arch. 1844, I. p. 161, Taf. V. fig. 6) and 

 Steenstrup (Untersuch. iib. das Vorkommen d. 

 Hermaphrodit. p. 66, Taf. I. fig. 18, e) with 

 Coryne ; finally by Kolliker (Nene Denkschr. 

 Vlli. p. 4S, fig. 20, 21, 22, 24) with Pennaria, 

 Eudendrium and Sertularia. In Crista, on the 

 other hand, Kiitliker found the spermatic particles 

 perfectly filiform, t 



* [ End of additional note to § 45.] The remark- 

 able relations here spoken of, and the conjectures 

 as to the real zoological nature of the animals in 

 question, have been pretty satisfactorily cleared up 

 by the recent researches of Agassiz. He has shown 

 that the Hydroid Polyps are not simply a lower 

 form of stemmed animals, producing at a given 

 period more highly-organized Medusae, but that 

 they are themselves, by their structure, real Medu- 



sae. See Lectures on Comparative Embryology, 

 1848; also Proceed. Amer. Assoc, for the Advance- 

 ment Sc. 1849 (" On the Plan of Structure and Ho- 

 mologies of Radiated Animals"), and Mem. Amer. 

 Acad. loc. cit. p. 225. — En. 



t [ § 46, note 2.] I have been able to trace the 

 development and character of the spermatic par- 

 ticles of many of the true Polyps and the Bryozoa. 

 The development occurs in special daughter-cells, 



