TUNICATA. 



1209 



to furnish the gelatinous covering of the 

 ova. 



The ova of Ascicl'uz, instead of passing from 

 the ovary to the branchiae, there to be deve- 

 loped as in a uterus, are emitted externally, by 

 the oviduct conveying them into the cloacal 

 cavity, whence they are carried outwardly by 

 the current of water through the external 

 anal aperture, or through the communicating 

 lateral opening into the branchial sac, and 

 thence through the branchial aperture. Cuvier 

 says that he found some minute egg-like 

 bo'dies between the branchial sac and the 

 mantle; a position very analogous to that 

 held by the ova of the bivalve Molluscs ; and 

 he thought it probable that ova so placed 

 were fecundated by seminal fluid emitted by 

 the same duct that leads from the ovary. 

 These granules, however, M. Savigny appa- 

 rently regards as little glands. 



The generative organs are sometimes single 

 and sometimes double ; in the latter case, the 

 two halves, right and left, are completely se- 

 parate, as in other Acephalans, and emit their 

 products separate!}' into the cloaca, which 

 serves as a kind of incubational or marsupial 

 pouch. 



The ovary is single in Phallusia, Pandocia, 

 and Dendrodoa ; it is usually double in Sol- 

 tenia, &c. In Cynthia the ovary is either 

 single or multiple, sometimes very large, form- 

 ing long groups of clustered globules, each 

 globule being crowded with ova. 



The single ovary is sometimes enclosed 

 within the intestinal loop, without adhering 

 to it, and sometimes, as in C. papillata, &c., it 

 lies against, and is adherent to, the rectum, 

 In C. papil'ata the ovary is bent on itself and 

 terminates by an oviduct at each end. In C. 

 canopus there are 24* or more ovaries ; those 

 on the right side are placed against the rectum, 

 and all terminate, as usual, by oviducts. In 

 C. microcosmus there are two ovaries on the 

 left side. They are composed of separate 

 gelatinous lobes, having the appearance of a 

 bunch of grapes. In C. myt'digera the ovary 

 has the form of a membranous pouch, which 

 furnishes points of attachment to the exterior 

 of the branchial sac, and is fixed to the mantle 

 and to the inner part of the intestinal loop. 

 Its duct is very thin, and follows the usual 

 course by the side of the rectum. In C. 

 2)oli/carpa and C. pomaria, Savigny describes 

 certain numerous hemispherical or conical 

 bodies adhering to the mantle, almost fifty in 

 number, and disposed in rows, somewhat cor- 

 responding to the six branchial folds, as being 

 possibly the ovaries of these species. These 

 bodies are without ducts j they are formed of 

 a mass of granules resembling the eggs of 

 some other Ascidians ; they are much com- 

 pressed, and resemble a compound berry held 

 in a 5-fid cup ; they have apparently no com- 

 munication with each other or externally, and 

 are accompanied at their base with gelatinous, 

 transparent, subpedunculated vesicles, appa- 

 rently empty. In C.papillata, which has other 

 generative organs, there are many rows of 

 isolated, gelatinous, semitransparent, wrinkled 



vesicles, corresponding to the arrangement of 

 the branchial folds, attached to the mantle, and 

 receiving bloodvessels from it. The lobes 

 of the ovary in C. microcosmus, after the emis- 

 sion of the eggs, wither into wrinkled vesicles 

 closely resembling these sessile vesicles in C. 

 papillata. Certain soft bodies observed in 

 C. microcosmus, and somewhat similar to the 

 above, Cuvier regarded as fat, serving as stores 

 of nutritive matter ; but with this Savigny 

 cannot agree. Savigny also points out the 

 occurrence of various irregular, but somewhat 

 similar fungous or fleshy excrescences on the 

 mantle (fig. 39. i, /, Vol. I. p. 1 12.), ovaries, 

 and intestines, sometimes even quite investing 

 the latter ; but these are quite distinct from 

 the ovary-like bodies above described. 



In Boltenia reniformis the ovaries are double, 

 unequal in size, elongate, formed of coarse 

 subcubical lobes, situated one on each side of 

 the body, and directed towards the anal 

 orifice; the right or smaller ovary, straight, 

 claviform, fitting closely into the ascending 

 loop formed by the stomach and intestine. 

 The left ovary, larger and less lobulated, is 

 on the opposite side, between the mantle 

 and the branchial sac ; it is undulating, and 

 extends downwards behind the branchial vein. 

 The tissue of these ovaries is a yellowish 

 membrane of distinctly cellular structure, 

 containing groups of large opaque ova and 

 smaller clusters of exceedingly minute diapha- 

 nous granules. The ovaries of Cystingia are 

 two free racemes composed of globular bodies, 

 as in Cynthia;, arranged on the two sides of 

 the body with the branchial sac and stomach 

 between them. In Dendrodoa (fig. 778. k) 

 the ovary is single and branched, consisting 

 of a trifurcate, cylindrical stem, bearing at 

 its base on one side a forked branch, and 

 on the other a simple one, all of the same 

 thickness ; it is situated on the left side of 

 the body between the mantle and the branchial 

 sac. In Chetyosoma, Professor Eschricht de- 

 scribes as an ovary two darkish bodies, filled 

 with vascular ramifications ; placed, one be- 

 tween the liver and the rectum, and the other 

 around the fold of the intestine. Another 

 somewhat similar organ, traversed by rami- 

 fying vessels, and placed at the anterior ex- 

 tremity of the body, is apparently the testicle. 

 Connected with this organ, a distinct sigmoid 

 duct runs to the right posterior angle of the 

 body, from whence a filamentous tube passes 

 along to the left posterior corner.* In Cynthia 

 ampulla the generative organs are situated in 

 the intestinal fold, and appear at first sight to 

 form a single organ ; but by the aid of the mi- 

 croscope two distinct organs, male and female, 

 are easily recognised (fig. 779. A). The testicle 

 forms a sort of framework around the ovary ; 

 it is of a milky white colour, and is composed 

 of an infinite number of short, twisted coeca, 

 visible to the naked eye, and somewhat ana- 

 logous to the seminiferous canals composing 

 the testicles of higher animals. Three or four 

 mammillary processes rise from the anterior 



* Royal Danish Transact, vol. ix. p. 13.- 



