62 ANATOMY OF THE ENOPLA. 



obtained), alter their shape apparently by bursting (Plate X, fig. 13), and seem like minutely 

 hirsute double rings, while the contained globules are scattered over the membrane. If the organ 

 has been ruptured and partly inverted, the free edge of the laceration and the shrivelled glands 

 are more easily observed (Plate X, fig. 21). The globules from the glandular papillae (Plate X, 

 fig. 17) and glands whose contents have been evacuated (rendering them minutely hirsute) readily 

 pass forward to the reservoir, and roll through the ejaculatory duct — under pressure. The func- 

 tion of the vast array of glands in this chamber would seem to be the formation and elaboration 

 of the peculiar fluid with the moving granules previously alluded to. This secretion is produced 

 in considerable quantities, and towards the posterior portion frequently distends the cavity as 

 a translucent pouch (Plate XI, fig. 16, a), wherein the granules are in full action, and even 

 the experienced are apt to err in regard to the nature of the movements, so like are they to 

 those caused by ciliary currents. Under a high power (700 — 1000 diam.) the molecules appear 

 as mere specks or points ; and they retain their curious motion for upwards of twenty-four hours 

 after extrusion from the cavity. There is thus a special fluid rich in these granules secreted by 

 the posterior chamber ; and continued observation, and the whole anatomy of the parts, show that 

 this fluid passes forward into the reservoir, where it is probably mixed with a small quantity of 

 another secretion from the glandular walls of the latter, and then propelled with force through the 

 ejaculatory duct into the anterior chamber. What its peculiar function in the anterior region, 

 or when discharged into the surrounding medium in the extruded state of the parts, may be, can 

 only be conjectured ; but, from the elaborate structure of the tissues concerned in its economy, 

 its action would seem to be important. I have no observations in support of the view that this 

 granular fluid is poisonous. It cannot pass into a wound at any rate until the stylet is withdrawn; 

 and if it really acts as a poison to animals when introduced into their tissues, it may reasonably 

 be supposed to affect them injuriously when discharged into the water around them. Whether 

 the liquid has any influence on the secretion of the stylets in the marginal sacs, or on the central 

 apparatus, I am unable to say ; but, as already stated, a minutely granular fluid has been seen in the 

 former, and stylets are not unfrequent in the posterior chamber of A. quicker. MM. de Quatrefages, 

 van Beneden, and others, state that the foregoing apparatus is used in attacking prey. I have 

 never observed the Enopla so engaged, and it may be asked, — Do the Anopla use their feeble and 

 unarmed structures for the same purpose ? The proboscis in the Enopla, indeed, is a somewhat 

 precarious aggressive weapon, for when extruded it frequently adheres to the irritating body, 

 and is thrown off. It is true a predatory function may be assigned with an air of probability to 

 the central stylet, but this cannot be done with those in the marginal sacs, for, being developed in 

 a free condition within almost closed cavities, they are quite useless as offensive organs. 



The walls of the posterior chamber, after forming the cul-de-sac, are continued backwards in 

 the form of one or two long translucent muscular ribands of extreme flexibility and contractility 

 (+, Plate XII, fig. 4), which are attached to the proboscidian sheath, rather behind the 

 middle of the animal ; the fibres spreading out in a fan-shaped manner, and mingling with those 

 of the tube. The motions of these muscular bands is most interesting, now jerking into 

 numerous graceful folds or coils by a sudden contraction, like the stalk of a Vorticella, and again 

 shortening more gradually — the curves being here and there thickened by the swelling of the 

 fibrillee. They are simply muscular fasciculi, which seem to restrain the irregular protrusion of 

 the proboscis, and assist in its retraction. This muscular arrangement is also the ultimum moriens, 

 showing contractions when all other signs of life have fled. In young animals the mobility of 



