496 



NA TURE 



{April 20y iSy( 



"Problems and Examples in Physics." We believe this col- 

 lection will be found useful by the student of other text-books of 

 Physical Science. There are 217 examples with answers. 



Mr. F. Green, writing from Cannes, April 16, states that he 

 had just seen, for the first time this year, a flight of about half-a- 

 dozen swallows. They were passing over his garden coming 

 from the sea, and going to the N. W. The nearest land to the 

 S, E. from Cannes is Corsica, no miles away. Last year the 

 first flight of swallows which he observed at Cannes was on 

 April II, and on the same day he heard the nightingale for the 

 first time of the season. This season he has not yet heard the 

 nightingale. 



The additions to the Zoological Society's Gardens during the 

 past week include an Indian Wild Dog {Cant's primcevus), a 

 Common Paradoxure {Paradoxurus typus) from the Deccan, pre- 

 sented by Col. A. C. McMaster ; a Small Hill Mynah {Gracula 

 religiosa) from India, presented by Mrs, A. E. Smithers ; a 

 Yellow-faced Amazon {Chrysotis xa7ithops) from S.E. Brazil, 

 presented by Mrs. Geo. B. Crawley ; two Common Boas {Boa 

 constrictor) from St. Lucia, presented by Mr. G. W. Des Voeux ; 

 four Trout {Salmofario), a Golden Tench (Tinea vulgaris) from 

 British Fresh Waters, presented by Mr. D. Banks. 



ABNORMAL MULTIPLICATION AND 

 ABORTION OF PARTS IN MEDUSA'- 



TDROF. L. AGASSIZ describes as of very rare occurrence 

 ■^ upon the American coast, a peculiar variety of Sarsia, pre- 

 senting six radial tubes, six oulli, and six tentacles. It therefore 

 becomes the more interesting to state that I met with a precisely 

 similar variety on the east coast of Scotland. Moreover, the 

 occurrence of this variety appears to be as rare in the one loca- 

 lity as in the other ; for of all the many thousands of Sarsia 

 which fell within my observation last summer, I only met with 

 one specimen of the variety in question. 



In nea.'ly all the species of naked and covered-eyed Medusae 

 which I had the opportunity of examining, there was a remark- 

 able absence of monstrous or mis-shapen forms. In the case of 

 one species, however, such forms were of frequent occurrence. 

 This species was Aurelia aurita, and the monstrosities showed 

 themselves both as abnormal multiplications and abortions of 

 parts. In all the cases of asymmetrical multiplication which I 

 observed, the peculiarity was confined to the lithocysts, and 

 always showed itself in the same manner. That is to say, I 

 hare several times observed, in otherwise normal specimens of 

 Aurelia aurita, the presence of nine instead of eight lithocysts, 

 and in all these cases the supernumerary lithocyst — which was 

 always fully formed and provided with the usual hood — was 

 placed beside and in close contact with one of the normal litho- 

 cysts. This latter fact appears to me important when considered 

 in relation to the theory of Pangenesis ; for upon this theory it 

 would follow that if a supernumerary lithocyst is to be deve- 

 loped at all, we should expect it to be so in apposition with one 

 of the normal lithocysts rather than in any other position. Our 

 ground for expecting this, of course, is that the theory of Pan- 

 genesis supposes similar gemmules to have a mutual affinity for 

 one another ; and as lithocyst gemmules would naturally be 

 plentiful in the region of any normal lithocysts during the pro- 

 cess of its development, or of its repair if injured, if anything 

 went slightly wrong in either of these processes, facilities would 

 be offered for the adhesions of improper gemmules at the point 

 where the disturbing cause acted, and these improper adhesions 

 having once taken place, and being then followed by normal 

 adhesions of proper gemmules, the result would probably be a 

 duplex organ. 



I have said that in all the cases of asymmetrical multiplication 

 of parts which fell under my notice, it was the lithocysts alone 

 that were affected. But besides these cases of asymmetrical 

 multiplication of parts in Aurelia, I saw several instances of 

 strictly symmetrical multiplication, and in all these instances 

 every part of the organism was equally — or rather proportionally 

 — affected. That is to say, as in the single instance of multipli- 



^ Extract from a paper on some new species and varieties of Medusae, 

 read 1]«f9r« the Linaean Society on April 6th, by George J. Rgmanes, 

 M.A. 



cation of parts which I observed in Sarsia, all the organs of the 

 nectocalyx— eye-specks, tentacles, and nutritive tubes— were 

 similarly affected ; so in the several instances of multiplication 

 of parts which I observed in Aurelia, all the organs of the um- 

 brella were similarly affected. If anyone will turn to the admir- 

 able plates contained in Prof. L. Agassiz's third contribution to 

 the Academy of Arts and Sciences, and representing a normal 

 specimen of the genus Aurelia, he will see that the nutritive 

 canals bear a very definite and symmetrical arrangement with 

 reference to one another, and also with reference to the 

 ovaries and lithocysts. In particular, there are sixteen prin- 

 cipal radial tubes that proceed in straight lines and without 

 branching from the centre to the circumference of the um- 

 brella. Of the sixteen tubes, one passes directly to each of 

 the eight lithocysts, while the remaining eight tubes alternatel 

 with these. Thus the sixteen radial tubes together mark ouf, as 

 it were, the whole umbrella into sixteen equal segments. Well; 

 in all the examples which fell under my notice of abnormal mul- 

 tiplication of parts in Aurelia (other than those of mere duplica- 

 tion of lithocysts), the precise and peculiar symmetry just de- 

 scribed was strictly adhered to ; in all these examples the undue 

 multiplication extended proportionally to ovaries, nutritive tubes, 

 lithocysts, and tentacles ; so that its effect was to increase the 

 number while adhering to the type of the natural segments abov< 

 described. It is further remarkable that in all the instances I 

 met with, the degree of abnormal multiplication was the sams 

 for in all the instances the ovaries were six, the principal or ua- 

 branched radial tubes twenty- four, and the lithocysts twelve. 

 All the parts, and therefore all the natural segments, were 1 

 in all the observed instances increased by one-third of i 

 normal number. It is curious to note that we have here the sa ,1 

 proportional increase as has already been described in the cast 

 oi Sarsia. This, of course, may be a mere accident ; but whei' -: 

 or not it is so, I think that, as there is certainly no reason eitli 

 the case of Sarsia or of Aurelta to regard the forms in questin. 

 distinct species, it becomes worth while to draw attention to ih 

 very definite manner in which the abnormal multiplication o 

 parts seems always to occur in ihese the only genera of Medusa 

 in which such multiplication has as yet been observed. It i| 

 perhaps worth while to add that in all the cases where I noticeci 

 this undue multiplication of parts, both in Sarsia and in Aurelia]^ 

 the animals were remarkable for the unusual amount of nervou! 

 energy which they displayed. There can be no doubt that thij 

 fact is to be attributed to the unusually large supply of nervoui » 

 matter that was secured to the organism by the multiplication ci( 

 its marginal bodies. 



As regards abortion of parts in Aurelia aurita, I cannot sa 

 that I have ever observed this to occur in any organs other tha 

 the ovaries. In these, however, suppression to a greater or les 

 extent is of pretty frequent occurrence. Most usual is the cas 

 where one of the four ovaries is of smaller size than the othe 

 three. Often the abnormal diminution extends to two alternat 

 or adjacent ovaries, and occasionally to three. More rare is th 

 case of total suppression of one ovary. Only on about a dozei 

 occasions have I seen total suppression of two ov.iries, and i 

 these it was sometimes the adjacent, but more frequently tb 

 opposite organs that were missing. Lastly, on one occasion ' 

 observed, in an otherwise well-grown specimen, a total abiencj 

 of three out of the four ovigerous pouches. In no case, it ma| 

 be added, did I observe that a deficiency or absence of ovigeroii 

 pouches entailed any corresponding deficiency or absence of aDj 

 other organs. 



I have said that, so far as my experience extends, neithil 

 reduction nor complete suppression of parts appears to occur i 

 any organs of Aurelia aurita, other than the ovaries. It then 

 fore becomes necessary to add that one or more of the lithocyst 

 with their hoods are frequently to be seen of smaller size tha 

 the others. As these variations, however, are usually attende 

 with a deficiency of the general tissue of the umbrella in tl 

 neighbourhood of the affected lithocyst, I am inclined to belies 

 that in these cases the small lithocyst is one that has been repn 

 duced to repair the loss of the original organ, which I suppo 

 to have been removed by mechanical violence of some kind- 

 mutilation which seems well indicated both by the deficiency ju 

 alluded to of umbrella tis-ue in the parts concerned, and also \ 

 the cicatrix-like appearance which is presented at the confines 

 these parts by such tissues as remain. In conclusion, I may sta 

 that towards the end of August all the individuals of this speci 

 began to undergo a marked diminution in size. Concurrent 

 with this dimuiution in size, the intensity of the pink colour- 

 which in this species is characteristic of the ovaries, nutriti 



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