. A manual of zoology. Zoology. 344 MOLLUSCA The goiuuls of the always diivcious Ccplialopoda are unpaired and lie far back in ihe \-ifceral sac. The duels in the female Octopoda (rarely ill the males) and in se^me Decapoda (OiL,'opsida) are paired. In Xaiilihis onlv the rii^ht duct is fiuictional in cither sex. although tlie left is well developed. Elsewhere llrere is only the left duct. The o\iducts are saccular with glaiulular walls; independently of them two pairs of open to the exterior, the accessory glands anil lite large nidame^ntal glands. 1 lie \as deferens (lig. 35S) is more
. A manual of zoology. Zoology. 344 MOLLUSCA The goiuuls of the always diivcious Ccplialopoda are unpaired and lie far back in ihe \-ifceral sac. The duels in the female Octopoda (rarely ill the males) and in se^me Decapoda (OiL,'opsida) are paired. In Xaiilihis onlv the rii^ht duct is fiuictional in cither sex. although tlie left is well developed. Elsewhere llrere is only the left duct. The o\iducts are saccular with glaiulular walls; independently of them two pairs of open to the exterior, the accessory glands anil lite large nidame^ntal glands. 1 lie \as deferens (lig. 35S) is more complicated. It has swellings known as seminal ^â esicle, prostate, and Xeedham's sac, in wliich the spennatophores are stored. These latter have such a complicated structure and show such motions when swollen with water that they -were long regardeil as para- sitic worms (hg. 350). The spennatophores are con\eyed to honl. i7, ai;lomic sac passing the female liy means of more or less modi- to tlie feft and above into the ,- i /i ^ ^ !⢠j\ i i 1 r ii 1 pericardium; c, ccelomic canal 'i- prostates; /, testis; /'.its , , â,, . ^ ... opening to cadom; , sentin^d enclosed. 1 lus part, wluch contiuns a vesicle. canal for the sp)ermatophores, cuts loose from the male, and can creep about for days in the mantle chamber of the female. Since it appears like an independent animal, it was I'lrst described as a parasitic worm under the name Ilalocolylus. In others the hectocotvlization is not carried so Fig. 3 ^8.â]\[a!e sexual organs of Sepia offu-iihilis tatter Grol> ^) Fig. 351).âSpcrmatophore of Si'pia drom TTatsclick, after Milne Edwards'). (J, dis- charging apparatus; b, packet of spermatozoa; c, envelope. The eggs arc cither fastened singly to aquatic plants or are laid in large gelatinous masses. Tliev are rich in yolk, and in ([uenee undergo partial discoidal segmentation (tig. 105). The blastoderm, on the end of the oval egg, forms the anlagen of the .se]
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
