MELICERTAD^E. 71 



grows in size from the addition of fresh matter, it is easy to see in what direction it 

 rotates, by means of the darker specks on its surface. If these are watched, it will be 

 found that every now and then the rotation is reversed, and that this happens many 

 times before the pellet is completed. It is needless to credit Melicerta with the volun- 

 tary alteration of the motion, for it is obvious that a pellet, kept in the centre of a ciliated 

 cup by the action of its cilia lashing up and down, must be in an unstable position ; a 

 very little alteration of its own figure, or of its centre of gravity, or of the relative power of 

 the cilia in different parts of the cup, would be sure to drive it out of its central position 

 to one side or the other. This done, the cilia on that side (say the lower one) would 

 be checked, and those on the upper would have the predominance, and so force the 

 pellet to rotate towards the upper side ; which when it had slowly reached, the upper 

 cilia would in their turn be checked, and the lower cilia would now have the pre- 

 dominance, and would again draw the pellet towards themselves, reversing the rotation 

 and so on. The particles in the cup are made to adhere by being mixed with the same 

 glutinous secretion as that which forms the inner tube. This exudes either from the cup 

 itself or (as I believe) from the surface of the large knob just beneath it (PL V. fig. 2c). 

 In a minute or two, from the commencement of the process, the pellet is completed, and 

 then the animal bends its neck swiftly over the edge of the cup, and clinches the pellet 

 on to the top of the inner tuhe, hy the opposing action of the chin and the knob beneath. 

 It is obvious that it selects the place in which to deposit the pellet, and it is probably 

 guided to the exact spot by its dorsal antenna, which is generally close to the spot the 

 instant before the pellet is laid. 1 It is curious that Ehrenberg should have completely 

 missed the way in which the pellets and tube are formed. He says that the former " are 

 not foreign bodies (as in the tube of Pliryganea] nor excrement ; but a peculiar substance 

 mixed with the latter, gummy, and hardening in water " : and he further says that he 

 distinctly saw the pellet discarded from the posterior intestinal opening, and fastened by 

 it to the tube. Mr. Gosse, who calls attention to this discrepancy, suggests that there 

 may possibly be " two species closely allied but differing in this part of their organisation 

 and economy " ; and the discovery of M. Janus, which has precisely the habit wrongly 

 ascribed to M. ringens, shows how shrewd was Mr. Gosse's suggestion. The only difficulty 

 about the matter is that Ehrenberg's drawings are certainly taken from M. ringens ; 

 while his description of the formation of the pellets and tube seems to be taken from 

 M. Janus. Possibly he may have found first the one, and then the other, and not dis- 

 tinguished between them ; though that seems hardly likely. 



Melicerta ringens in England does not usually occur in clusters of adhering indi- 

 viduals, though occasionally one is seen with a young one or two attached to its tube. 

 But in the United States (as I have already noticed) it frequently occurs in large clusters, 

 and some of the tubes of these clusters greatly exceed in size the largest known English 

 specimen. For instance, I possess a cluster in which the central tube is -J- of an inch 

 long, and of which therefore the tenant must have been upwards of -| of an inch in 

 length, thus exceeding even the great length of Floscularia Hoodii. I found that this 

 great tube contained upwards of six thousand pellets arranged in about two hundred 

 and forty rows, one above another. 



The Male. Judge Bedwell in the " Midland Naturalist " (loc. cit.) describes a small 

 free-swimming Eotiferon which he saw emerge from a tube of Melicerta ringens. It 

 was not more than J of the length of the tube, had a forked foot, and trQphi somewhat 

 like an inverted W, which were capable of protusion through the corona. Like the prob- 

 able male of M. conifera* " it began to woo and caress the lobes of the female in the 

 most active and elegant manner, almost as if it were nibbling the main wreath of cilia. 

 Now to anyone accustomed to watch Melicerta, it must always be a matter of astonish- 

 ment to see such a timid, nervous rotifer allow another to touch the cilia with impunity ; 

 but in this instance the female never flinched in any way, but accepted the attentions of 

 1 Judge Bedwell, Mon. Micr. J. (loc. cit.). The whole paper is most suggestive. 

 2 See Mr. Gosse's description, p. 72. 



