426 



NATURE 



\Sept. 19, 1872 



In the younger ones the contractile space of the unchanged zooid 

 was still very evident, but was fixed, showing no tendency to 

 alteration of size, and the so-called nucleus was very distinct and 

 larger than iu the ordinary zooids. The whole was enveloped 

 in a transparent gelatinaus-luoking investment. 



In a slightly mare advanced stage another envelope, in the 

 form of a brown horny capsule, begins to be secreted between 

 the proper wall of the zooid and the external gelatinous invest- 

 ment. It is at first thin and smooth, but it gradually acquires 

 considerable thickness, and becomes raised on its outer surlace 

 into riilges enclosing hexagonal spaces. 



In this stage the capsule has become too opaque to admit of a 

 satislactory view into its interior ; but if the capsule be carefully 

 opened its contents may be liberated so as to render apparent 

 their real nature. It will be then seen that these consist of a 

 minutely granular semi-fluid plasma surrounding the "nucleus," 

 which has much increased in size and occupies a large portion of 

 the cavity of the capsule. The condition of the contractile 

 space could not be determined ; it has probably altogether dis- 

 appeared. 



In a further stage the "nucleus" has undergone an important 

 change ; for, instead of the long cylindrical form it had hitherto 

 presented, it has become irregularly branched, has acquired a 

 softer consistence, arid has m.)reover broken itself up into two 

 or more pieces. This change in the "nucleus "is invariably 

 accompanied by the appearance of nucleated cell-like bodies, 

 which are scattered through the corpuscular plasma which had 

 filled the rest of the capsule. They are of considerable size, of 

 a spherical form, and with their nucleus occupying the greater 

 part of their cavity, and having its nucleolus represented by a 

 cluster of granules. 



' In other capsules, apparently the more advanced, no trace of 

 the so-called nucleus of the vorUcella body could be detected, 

 and it seems to be entirely repLiced by tiie spherical nucleated 

 cells, which hadjnow still further increased in number. It is 

 impossible not to regard these cells as the result of the disinte- 

 gration of the nucleus, and the conclusion is a legitimate one 

 th,t they are finally liberated by the natural dehiscence of the 

 capsule, aud become developed into new vorticellidans. 

 On the Structure of Noctilaca, by Pro.f. AUman. 

 The author gave an account of some researches he had made 

 on Noctiluca inolicus. They were mostly confirmatory of the 

 results arrived at by other observers, more especially by Krohn, 

 Qaatrefages, Busch, Huxley, andWebb, while they further served 

 to supplement the observations of these zoologists. 



At one end of the meridional depression is the vibratile 

 flagellum with the mouth at its base, and here the depression 

 becomes quite superficial, while the opposite end is much deeper 

 and is here abruptly closed. Just outside of this deep end of the 

 depression there commences, by a funnel-shaped enlargement, a 

 very slightly elevated ridge of a firmer consistence than the rest of 

 the body ; it terminates abruptly after running down, in a 

 meridional direction, over about one-third of the circumference 

 of the body. The author had reason to believe that this ridge is 

 traversed in its length by a canal which opens close to the ab-oial 

 extremity of the meridional depression by a funnel-shajjed 

 orifice, thus giving support to the opinion of Huxley, who 

 believes that Noctiluca is provided with an anal orifice. The 

 mouth leads into a short cylindrical gullet, and the author con- 

 firmed the existence of the vibratile cilium contained within 

 the gullet, as originally described by Krohn ; and of the ridge, 

 with its projecting tooth, described by Huxley as existing in lire 

 gullet walls. The lloor of the gullet is formed by the central 

 mass of protoplasm, here naked and in direct ;contact with the 

 surrounding medium. The vibratile cilium springs from this 

 floor, aud near the root of the cilium is a depression in the floor 

 which can be followed for a little distance into the protoplasm. 

 Besides the well-known branching processes which radiate from 

 the central mass of protoplasm to the walls of the body, there is 

 also sent off from the central mass a broad, irregularly qu.adrangu- 

 lar, plate-like process, which extends to the outer walls, wtiere 

 it becomes attached along the line of the superficial meridional 

 ridge. The lower free edge of this broad process is thickened in 

 the manner of a hem. 



In contact with the central protoplasm is the nucleus, a clear 

 spherical body about innnt of "" '"'^'i '" diameter. 



The body walls are composed of two layers — an external thin, 

 transparent, and strvictureless membrane, and an internal thin 

 granular layer of protoplasm, which lines the structureless mem- 

 brane throughout its whole extent, and which receives the ex- 



tremities of the radiating processes from the central mass. Under 

 the action of iodine solution and other reagents, the protoplasmic 

 layer may be seen to detach itself from the outer structureless 

 membrane, and, along with the radiating bands, contract towards 

 the centre. It admits of an obvious comparison with the primor- 

 dial utricle of the vegetable cell. 



The flagellum, which is given off close to the margin of the 

 mouth, is a flattened band-like organ, gradually narrowing 

 towards its free extremity, and with its axis transversely striated 

 like a voluntary muscular fibre throughout its whole length. It 

 seems to have the power of elevating its edges, so as to render 

 one of its surfaces concave, and thus becomes converted into a 

 semi-tube, which may assist in the conveyance of nutriment 

 towards the mouth. 



The nucleus is a spherical vesicle, with clear colourless 

 contents, among which minute transparent oval corpuscles 

 may usually be detected. When acted on by acetic acid, the 

 difference between the contents of the vesicle and its wall be- 

 comes very api^arent, and the contents may now be seen accu- 

 mulated towards the centre as a minutely granular mass, with 

 some of the oval corpuscles entangled in it. 



The radiating offsets, which extend from the central protoplasm 

 to the peripheral layer, contain well-defined clear corpuscles 

 which slowly change tiieir relative );'laces, as if under the influence 

 of very feeble currents. These offsets, indeed, closely resemble 

 the radiating protoplasm filaments which extend from the proto- 

 plasm, surroun'iing the nucleus, to the walls of the primordial 

 utricle in the vegetable cell. The peripheral layer contains 

 scattered through it numerous minute cell-like bodies. These 

 are spherical and of various sizes ; in the larger ones a distinct 

 central nucleus may be detected. 



It is scarcely correct to regard tlie central mass of protoplasm 

 as a true stomach. The author had failed to find any evidence 

 of a permanent gastric or somatic cavity, and he regarded the 

 protoplasm ntas^ to which the gullet leads as representing the 

 "parenchyma" of the Infusoria, and, like this, allouing of the 

 solid food being forced down into it from the gullet and there 

 encysted in extemporaneously formed vacuolar. The food also 

 frequently forces its way from the central mass into the radiating 

 processes, and diatoms and other microscopic organisms may be 

 seen in these processes enclosed in cyst-like dilatations of them, 

 extemporaneously lormed for their reception at various distances 

 from the central protoplasm. 



It was considered probable that the canal which seems to exist 

 in the superficial ridge affords exit for certain effete matters, 

 wiiich may be conveyed to it through the process, by which it 

 is kept in connection with the central protoplasm. 



Our knowledge of the phenomena of reproduction and develop- 

 ment in Noctiluca is still very imperfect, and the author saw little 

 which seemed capable of throwing additional light on this sub- 

 ject. He agreed, however, with Huxley in regarding it as pro- 

 bable that tile nucleated celMike bodies which are present in the 

 peripheral layer of protoplasm have a reproductive function, 

 and are destined after liberation to become developed into new 

 individuals. 



From the account now given it w'iU be apparent that Noctiluca 

 consists essentially of an enormously vacjofated protoplasm, in- 

 volving a nucleus and enclosed in a structureless sac, the 

 vacuolation taking place to such an extent as to separate the 

 contents into a peripheral layer of protoplasm wdiich remains ad- 

 herent to the outer sac, and into a central mass which is kept in 

 communication with the peripheral layer by processes of proto- 

 plasm which pass from one to the other. The author believed 

 ihat the nucleus of Noctiluca had a significance different from that 

 of the so-called nucleus of the ordinary Infusoria, and that it ad 

 mitted of a closer comparison with the true cell-nucleus. He was 

 of opinion that the nearest ally of Noctiluca would be found in 

 the somewhat anomalous infusorial genus Peridinia. 



In conclusion the author detailed some observations he had 

 made on the luminosity of Noctiluca ; and he gave reasons for 

 maintaining that the seat of the phosphorescence is entirely con- 

 fined to the peripheral layer of protoplasm which lines the exter- 

 nal struclurcless membrane. 



On the Structure of Edwardsia, by Prof. AUman. 

 The structure of this beautiful little actinozoon differs in many 

 important points from that of both the zoantharian and alcyonarian 

 polypes. It was shown that just within the moath the walls of 

 the stomach sac project into the cavity of the sac in such a way 

 as to form eight complicated frill-like lobes ; that the eight 

 vertical, radiating lamella which project into the body cavity 



