Feb. 20, 1890] 



NATURE 



377 



botanists as species ; and that one expert has made no fewer 

 than thirty-seven species of one set of forms, which another 

 arranges in three, besides, even in the cases where successive 

 naturalists have agreed in separating certain forms, and in con- 

 sidering them true species, it happens now and then, as it did 

 to myself, that a chance discovery throws down the barriers, and 

 unites half-a-dozen species into one. 



Under these circumstances one would have expected that the 

 tendency would have been to be chary of making new species, 

 and no doubt this is the practice of the more experienced 

 naturalists ; but, among the less experienced, there is a bias in 

 the opposite direction ; and all of us, I fear, are liable to this 

 bias when we have found something new ; for, even if it is 

 somewhat insignificant, we are inclined to say with Touchstone, 

 "A poor thing, sir, but mine own!" Now, were this fault 

 mended, much would be avoided that tends to make monographs 

 both expensive and dull ; for, though the needs of science 

 require a minute record of the varieties of form, which are 

 sometimes of high importance from their bearing on scientific 

 theories, yet the description of them, as varieties, may often be 

 dismissed in a line or two, when nothing further is set forth 

 than their points of difference ; whereas, if these forms are 

 raised to the rank of species, they are treated with all the spaced- 

 out dignities ot titles, lists of synonyms, specific characters, &c., 

 &c., and so take up a great deal of valuable room, weary the 

 stuaent with repetitions, and divert his attention from the typical 

 forms. 



But when everything has been done that seems desirable, 

 when names and classification have been made both simple and 

 stable, and the number of species reduced to a minimum, there 

 will still remain the difficulty that monographs must, from the 

 nature of the case, generally be grave, as well as expensive 

 books of reference, rather than pleasant, readable books, within 

 the reach of the majority. I would suggest then, that, if it be 

 possible, each group of animals should be described not only by 

 an all-embracing monograph, to be kept for reference on the 

 shelves of societies like our own, but by a book that would deal 

 only with a moderate number ot typical, or very striking forms ; 

 that would describe ttiem fully, illustrate them liberally from 

 life, and give an ample account of their lives and habits. 



Such a book should give as little of the classification as 

 possible ; it should aVoid the use of technical terms, and above 

 all, It stiould be written with the earnest desire of so interesting 

 tne reader in the subject, that he should fling it aside, and rush 

 ott to find the animals themselves. By this means we should 

 not only get that active army of out-of-door observers, which 

 science so greatly needs ; but, by bringing the account of each 

 group into a reasonable compass, we stiould enable students of 

 natural tiistory to get a fair knowledge of many subjects, and so 

 greatly widen their ideas and multiply their pleasures. 



For why should we be content to read only one or two 

 chapters ot Nature's book? To be interested in many things — 

 1 had almost said in everything — and thus to have unfailing 

 agreeable occupation for our leisure hours, is no bad receipt for 

 nappiness. But life is short, and its duties leave scant time for 

 such pursuits ; so that to acquire a specialist's knowledge of one 

 suuject would often be to exchange the choice things of many 

 subjects lor the uninteresting things of one. And how uninter- 

 esting many of them are ! How is it possible for any human 

 oein^ to take pleasure in being able to distinguish between a 

 uozcii similar creatures, that differ from one another in some 

 tritling matter ; that have a spike or two more or less on their 

 backs, or a varying number ot undulations in the curve of their 

 jaws, or differently set clumps of bristles on their foreheads? 

 Why should we waste our time, and our thoughts, on such 

 matters ? The specialist, unfortunately, must know these things, 

 as well as a hundred others equally painful to acquire and to 

 retain, and no doubt he has his reward ; but that reward is not the 

 ucep delight that is to be found in the varied study of the humbler 

 animals ; of those beings "whom we do but see, and as little 

 know their state, or can describe their interests or their destiny, 

 as we can tell of the inhabitants of the sun and moon ; . . crea- 

 tures who are as much strangers to us, as mysterious, as if they 

 were the fabulous, unearthly beings, more powerful than man, 

 ycL his slaves, which Eastern superstitions have invented." 



those, then, who are blest with a love of natural history 

 should never dull their keen appreciation of the wonders and 

 beauties of living things, by studying minute specific differences ; 

 or by undertaking the uninteresting office of finding and record- 

 ing animals, that may indeed be rare, but which difi'er from those 



already known in points, whose importance is due solely tor 

 arbitrary rules of classification. 



This eagerness, to find something new, errs not only in 

 wasting time and thought on m.atters essentially trivial and dull, 

 but in neglecting things of the greatest interest, which are always 

 and everywhere within reach. Take, for instance, the case of 

 Melicerta ringens. What is more common, what more lovely, 

 than this well-known creature ? And yet how much there 

 remains to be found out about it. No one, for example, has 

 ever had the patience to watch the animal from its birth to its^ 

 death ; to find out its ordinary length of life, the time that it 

 takes to reach its full growth, the period that elapses between 

 its full growth and death, or, indeed, if there be such a period. 

 And yet even these are points which are well worth the settling. 

 For, if Meliceria reaches its full growth any considerable time 

 before the termination of its life, it would seem probable that, 

 owing to the constant action of its cilia, it would either raise its 

 tube far above the level of its head, or else be constantly 

 engaged in the absurd performance of making its pellets and 

 then throwing them away. Who has ever found it in such a 

 condition, or seen it so engaged ? yet the uninterrupted action of 

 the pellet cup would turn out the six thousand pellets, which 

 form the largest tube that I am acquainted with, in about eight 

 days, and those of an average tube in less than three ; while the 

 animal will live (according to Mr. J. Hood) ^ nearly three 

 months in a zoophyte trough, and no doubt much longer in its 

 natural condition. It is true that the creature's industry in 

 tube-making is not continuous. It is often shut up inside its tube, 

 when all ciliary action ceases ; and, moreover, when expanded, 

 it may be seen at times to allow the formed pellet to drift a\yayf 

 instead of depositing it ; but, allowing for this, there is no little 

 difficulty in understanding how it is that, with so vigorous a 

 piece of mechanism as the pellet-cup, the tube at all ages, 

 except the earliest, so exactly tits the animal. I am aware that 

 it has been stated that the whole of the cilia (including those of 

 the pellet-cup) are under the animal's control, and that their 

 action can be stopped, or even reversed, at pleasure. But this, 

 I think, is an error. Illusory appearances, like those of a turning 

 cog-wheel, may be produced by viewing the ciliary wreath from 

 certain points, and under certain conditions of illumination ; and 

 these apparent motions are often reversed, or even stopped, by a 

 slight alteration either in the position of the animal, in the direction 

 of the light, or in the focussing of the objective. When, how- 

 ever, under any circumstances, the cilia themselves are distinctly 

 seen, they are invariably found to be simply moving up and 

 down ; now turning sharply towards their base, and now 

 recovering their erect position. Even the undoubtedly real 

 reversal of the revolution of the pellet in its cup, which is- 

 constantly taking place, can be easily explained by purely 

 mechanical considerations, and consistently with the continuous 

 up and down motion of the cilia. Moreover, of the actual 

 stoppage of the cilia, in the expanded Rotiferon, I have 

 never seen a single instance. In all cases, on the slightest 

 opening of the corona, the cilia begin to quiver, and they are 

 always in full action, even before the disk is quite expanded; 

 I while, should a portion of the coronal disk chance to be torn away, 

 I its cilia will continue to beat for some time after its severance : 

 1 so that there is good reason for believing, that the ciliary action 

 j is beyond the animal's control. 



It IS possible, indeed, that Melicerta may continue to grow (as- 

 j Mr. Hood says that the Floscules appear to do) as long as it 

 ' lives ; or it may adopt the plan of some species of (Ecisies, 

 which, to prevent themselves from being hampered by their 

 ever-growing tubes, quit their original station at the bottom of 

 the tube, and attach themselves to it above, creeping gradually 

 upwards as the tube lengthens. At any rate it would be 

 interesting and instructive to watch the growth of a Melicerta, 

 and the building of its tube, from the animal's birth to its death. 

 An aquarium, in which Melicerta would live healthily and breed 

 freely, could easily be contrived, and a little ingenuity would 

 enable the observer to remove any selected individual to a 

 zoophyte trough and back again, without injury ; and his tfo^D'^ 

 perhaps would be further repaid by such a sight as once delighted 

 my eyes at Clifton, where I picked, from one of the tanks of 

 the Zoological Gardens, some Vallisneria, whose ribbon-like 

 leaves were literally furred with the yellow-brown tubes of 



■ Mr. Hood, of Dundee, has kept in his troughs Melicerta ringens for 79- 

 days, Limnias ceratophylli for 83 days, Cephalosiplton limntas foj 89 days . 

 the Floscnlarice usually lived abjut 50 days ; but F. Hoodn died, before 

 maturity, in 16 days. 



