68 



LUCEKNARI^ AND THEIR ALLIES. 



the wall upon itself. J]acli pouch or follicle containa either a certain amount of 

 spernuitogcnous material (./(>. 75, 76), or one, two, or three eggs {fig. 74, g), accord- 

 ing- to wliether the individual is male or female. The follicles crowd closely upon 

 each other, and all open into the central chamber. At the appointed time, when 

 the eo-o-s or spermatozoa are ripe, they are discharged from the mouths of the 

 pouches into the general chamber («') of the saccule, and thence pass outward, 

 through the lateral aperture (s") in the neck, into the broad caraerae of the umbella. 

 A full description of the eggs and spermatozoa may be found in the chapter on 

 Embryoloo-y. As well as we can make out, there are from one hundred to one 

 hundred and twenty-five pouches in a fully developed saccule. Their mouths are 

 closcMJ until near the time for the extrusion of their contents, and then, especially 

 in the males, they are rather wide open. The space between the central chamber 

 and the outer wall is almost entirely filled by the follicles and their contents, but 

 what is left is occupied by the muscular layer {oomyoplax) and the chondromyoplax 

 (b^). The ooriit/opJax envelops the pouches like a stroma, and it might not inaptly 

 be compared to that, and tlie oopltragma to a tunica granulosa. The fibrillfc of the 

 chondromijoplax are arranged with tolerable regularity in the region of the neck, 

 stretching directly from the outer to the inner fold of the wall of the saccule ; but 

 where they mingle with the pouches they form a sort of irregular mesh or network, 

 and are not to be distinguished positively from the fibres of the muscular layer. 

 This only serves to confirm us in the belief that all those fibrillar which traverse 

 the chondromyoplax in any part of the body are prolongations from the muscular 

 layer, although we would not claim that they are identical with the muscular 

 fibrillae, but rather a prolongation of connective tissue. After the discharge of their 

 contents the saccules collapse and shrivel to two-thirds or even one-half their former 

 size, and the follicles gape widely and assume irregular shapes {fig. 77), while the 

 fibrilloe of the chondromyoplax appear to be torn or more irregular than ever. An 

 empty follicle {fig. 79) seems to be dotted all over its outer surface, but if examined 

 by a profile view these dots turn out to be the broken and retracted fibrillae of the 

 cJiondromyoiilax. 



138. Genitalia of StroUloida. — This investigation reveals to us here the fact 

 that there is a double differentiation in the reproductive organs, which, when 

 contrasted with the condition of the liomologous organs in the Strobiloida, assumes 

 the highest morphological importance. We do not intend to discuss the matter at 

 this point, but will merely state the significant facts, that not only, as mentioned 

 above (^ 132, 133), do the genitalia of the Strobiloida form a continuous part of the 

 umbellar parietes, but the eggs are simply immersed in the cliondroviyoplax, close 

 to, and partly imbedded in, the opsomijoplax, i. e., just beneath the exterior wall 

 of the circumoral area. In the males the spermatogenous material lies in hollows 

 in the same layer as do the eggs in the female, but a sort of follicle is formed about 

 them by a superabundant gathering of fibrilla; which are prolonged principally 

 from the opmmyoplax. This is their nearest approach to a true follicle that we 

 have met with. Tiie walls, strictly speaking, have nothing to do with it. We 

 shall dwell at length on this point in the chapter (Part XI) assigned to the 

 -latomy and morphojogy of Aurelia, and need not, therefore, proceed to further 



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