118 DEVELOPMENT OF THE ANOPLA. 



a pale oleaginous space, while yet in the body of the female (Plate XXIII, fig. 1). The 

 flask enveloping them is composed of a fine hyaline membrane, that assumes many silky folds 

 in the collapsed condition, and evidently contains a fluid which, with the semi-solid yolks, may 

 be thrust out into the mucus. The cleavage of the vitellus generally commences on the second 

 day, when in some it is found divided into two and in others into four parts (Plate XXIII, 

 fig. 3). As first pointed out by Max Schultze, Desor was in error when he stated that the 

 irregularity of the divisions of the vitellus distinguished this species from other animals. The 

 divisions proceed regularly and somewhat rapidly ; for ova which presented four lobes at 9 a.m. 

 were found at 1 p.m. broken into a number of rounded masses, so that each had a nodular 

 or mulberry-aspect (Plate XXIII, figs. 5 and 6). No clear spot is observed in the centre of 

 the secondary masses (Plate XXIII, fig. 4). During the next four or five days the changes 

 consist chiefly of subdivisions of the vitellus. There is now a pale spot in the ovum, 

 and a few free granules and cells in the flask, as noticed by Desor. Each likewise 

 assumes a smoother outline from subdivision of the vitellus, and only a few nodules appear here 

 and there on the otherwise even circumference. E. Desor found the ova ciliated on the twelfth 

 and fourteenth days, Max Schultze on the eleventh and twelfth, and I have struck the average 

 amongst the British examples on the latter date. The ova, again, which had been left entirely 

 above the water-line did not develop so quickly. At first the ciliation does not cause the mass 

 to revolve, but subsequently this motion takes place with vigour (Plate XXIII, fig. 7). They 

 continue in this condition about a month, and then a further change ensues in the contents of 

 the flasks (Plate XXIII, fig. 8) ; and the latter drawing will explain E. Desor's discovery, as well 

 as enable me to correct a slight inaccuracy into which he has fallen. The opaque ciliated mass 

 previously noticed by-and-by shows a double outline under pressure, caused by the development 

 of the young Lineus within the ciliated coating ; indeed, at an advanced stage, as in the middle 

 of the flask represented in Plate XXIII, fig. 8, the embryo seems to be shrouded in a layer of 

 fatty cells and oil-globules (b), within which it distinctly moves. In such a condition the animal 

 readily escapes from its investment, and at the upper part of the same flask a free example [a) is 

 seen. E. Desor falls into a slight error in his excellent description, when he states that the cells 

 in the interior of the embryo are the " residue of the vitellus destined for the support of the 

 animal ;" they are nothing else than the cells in the developing wall of the alimentary canal. 

 The large dark ciliated mass (c) at the lower part of the flask, and the scattered cells and 

 granules, are portions of the discarded external covering of the embryo ; and it is to be observed 

 that the cilia on this texture are somewhat longer than those on the free young animal, though 

 their motion is less vigorous. The " cells" of which this rejected covering is made up are 

 entirely of a fatty nature (Plate XXII, fig. 6) — in short, an aggregation of fatty granules, with 

 an oil-globule or two, and capable of changing form accordingly. It is a fact that this debris 

 after a time quite disappears from the flask, and therefore it probably acts as nourishment for the 

 young (being swallowed by the mouth, as in the case of the embryo of Purpura lapUlus) just as 

 the yolk-sac, by a different mode, does in other animals. In escaping from the flask, the young 

 animals, in many cases, seem to have thrust themselves along the narrow apex, dilating it and 

 bursting through. 1 Eor a considerable time afterwards, both in captive and littoral cases, 

 they crawl in swarms amongst the gelatinous mucus, so that the latter has a strange aspect, 



1 E. Desor makes the following remark about the young Lineus, when removed from the 

 flask : — " It appears perfectly master of its movements, and on seeing it swimming about, and striking 



