4o6 



NA TV RE 



[August 21, 1890 



two species the legs are neither modified nor adorned to any 

 remarkable extent. 



It must be understood that the few instances here given of 

 the secondary sexual characters have been selected out of a 

 number cited by the author, who could himself have filled a 

 volume on the subject. Sufficient, however, have been given to 

 show how commonly the anterior portion of the body varies in 

 different ways in the male sex ; and " it is of high importance 

 to note that the bright-coloured hairs or metallic scales as well 

 as the protuberances are either on the anterior surface, or in 

 some way so placed as to be plainly in view from the front." 



In seeking for an explanation of these sexual characters it 

 does not appear that any of them are of special advantage to 

 tfieir possessors in the way of procuring food, avoiding enemies, 

 fighting with rivals, &c. ; consequently they cannot be attributed 

 to the action of natural selection. But when considered in 

 connection with the habits of the Attidce at the time of mating, 

 it is clear to the mind of the author that the clue is to be found 

 in the theory of sexual selection. The courtship of a number of 

 captive species is described, and described with a sense of the 

 ludicrous which is quite irresistible. The following two may be 

 selected as instances. 



On p. 37 we read of Sailis pulex : — " On May 24, we found a 

 mature female, and placed her in one of the larger boxes, and 

 the next day we put a male in with her. He saw her as she 

 stood perfectly still, twelve inches away ; the glance seemed to 

 excite him, and he at once moved towards her; when some four 

 inches from her he stood still, and then began the most remark- 

 able performances that an amorous male could offer to an 

 admiring female. She eyed him eagerly, changing her position 

 from time to time so that he might be always in view. He, 

 raising his whole body on one side by straightening out the legs, 

 and lowering it on the other by folding the first two pairs of 

 legs up and under, leaned so far over as to be in danger of 

 losing his balance, which he only maintained by sidling rapidly 

 towards the lowered side. The palpus, too, on this side was 

 turned back to correspond to the direction of the legs nearest it. 

 He moved in a semicircle for about two inches, and then in- 

 stantly reversed the position of the legs and circled in the 

 opposite direction, gradually approaching nearer and nearer to 

 the female. Now she dashes towards him, while he, raising his 

 first pair of legs, extends them upward and forward as if to hold 

 her off, but withal slowly retreats. Again and again he circles 

 from side to side, she gazing towards him in a softer mood, 

 evidently admiring the grace of his antics. This is repeated 

 until we have counted in circles made by the ardent little 

 male. Now he approaches nearer and nearer, and when almost 

 within reach whirls madly around and around her, she joining 

 and whirling with him in a giddy maze. Again he falls back 

 and resumes his semicircular motions, with his body tilted over ; 

 she, all excitement, lowers her head and raises her body so that 

 it is almost vertical ; both draw nearer ; she moves slowly 

 under him, he crawling over her head, and the mating is 

 accomplished." 



Again, on p. 47, conc^xmwg Dendryphantes elegans : — "While 

 from three to five inches distant from her, he begins to wave his 

 plumy first legs in a way that reminds one of a windmill. She 

 eyes him fiercely, and, he keeps at a proper distance for a long 

 time. If he comes close she dashes at him, and he quickly 

 retreats. Sometimes he becomes bolder, and when within an 

 inch, pauses, with the first legs outstretched before him, not 

 raised as is common in other species ; the palpi also are held 

 stiffly out in front with the points together. Again she drives 

 him off, and so the play continues. Now the male grows 

 excited as he approaches her, and while still several inches away, 

 whirls completely around and around ; pausing, he runs closer 

 and begins to make his abdomen quiver as he stands on tip-toe 

 in front of her. Prancing from side to side, he grows bolder 

 and bolder, while she seems less fierce, and yielding to the 

 excitement, lifts up her magnificently iridescent abdomen, holding 

 it at one time vertical, and at another sideways to him. She 

 no longer rushes at him, but retreats a little as he approaches. 

 At last he comes close to her, lyin^ flat, with his first legs 

 stretched out and quivering. With the tips of his front legs he 

 gently pats her ; this seems to arouse the old demon of resist- 

 ance, and she drives him back. Again and again he pats her 

 with a caressing movement, gradually creeping nearer and 

 nearer, which she now permits without resistance, until he 

 crawls over her head to her abdomen, far enough to reach the 

 epigynum with his palpus." 



From these cases and the others that are given it is established 



NO, 1086, VOL. 42] 



that the attitudes and antics of the males are such as to display 

 to the best advantage whatever adornments they possess, and it 

 is concluded that the female selects as her mate the male which 

 pleases her best on account of some superiority over his fellows 

 in adornment either of colour, or special outgrowths, or both. 

 Hence is deduced the further conclusion that the sexual orna- 

 ments of the male result from the constant preference by the 

 females of the best-decorated males. But it is obvious that this 

 conclusion is open to the same criticism as that advanced against 

 Mr. Darwin's explanation of the sexual ornamentation of, e.g. , 

 birds — namely, the criticism that the conclusion rests upon an 

 inference and not upon a fact ; and that the most important link 

 in the whole chain of evidence is wanting — namely, the proof 

 that the females select as partners the most beautiful males. 

 This it will be remembered, is perhaps Mr. Wallace's strongest 

 objection to the hypothesis of sexual selection ; and when we 

 consider all the cases that are quoted in this work it will be 

 seen that many of those that are advanced as supporting this 

 hypothesis are equally explicable by Mr. Wallace's views. 

 Thus, although it is certainly the case that the females are as a 

 rule the more powerful and more ferocious, yet, on the other 

 hand, judging from the descriptions given of the contests and 

 dances of the males, it seems to be this sex which excels in 

 activity ; and if activity be a criterion of high vitality we at 

 once see the connection between high vitality and ornamenta- 

 tion. Again, from the fact that the female watches with atten- 

 tion the antics and gambols of the male, it is inferred that she 

 is admiring the display of his agility and beauty : that, of course, 

 may be the case, but is it not conceivable, considering the 

 ferocity of her disposition, that she is merely on the alert to 

 ward off an unwelcome advance, or is but awaiting a favourable 

 opportunity to seize and destroy her persecutor? Or again, if it 

 be asked why it is that the males perform the strange antics in 

 the presence of the females if it be not for display, it may be 

 answered that the excitement of the males, always great during the 

 breeding season, attains to a maximum at that time in the society 

 of the females, and shows itself in the performance of the strange 

 antics that are so graphically described. The same objection 

 may be made to the idea expressed on p. 41 that the seemingly 

 terrible battles of the males are all sham affairs gotten up for the 

 purpose of displaying before the females. The fact that the males 

 fight when there is no female to watch them makes it more probable 

 that the combats are due to playful excitability or genuine ferocity. 

 And lastly, not only, as above stated, is there a lack of evidence 

 to show that the female prefers as partner the most beautiful 

 male ; but, more than that, it appears that the success of one 

 male over another in courtship may be attributed to excess of 

 vigour. Thus, in the case of Astia vittata, a species in which 

 there are two types of male, it is stated on p. 54 that "the 

 niger form is much the more lively of the two, and whenever 

 the two varieties were seen to compete for a female, the black 

 one was successful. He is bolder in his manners . . . " ^ 



Thus Mr. Peckham has not yet brought forward a sufficient 

 number of facts to carry to all minds that conviction of the 

 truth of the theory of sexual selection which he feels himself. 

 But whatever be the value of the criticisms here advanced, and 

 of others that will doubtless be thought of, everyone will admit 

 that the paper contributes a number of new and interesting facts 

 to the subject of sexual adornment, and most of its readers will 

 probably feel inclined to think that the balance of the evidence, 

 so far as spiders are concerned, tends to support the explanation 

 proposed by Mr. Darwin. R. I. PococK. 



THE TERMINOLOGY OF HYDROLYSIS, ES FE- 

 CI ALL YAS EFFECTED BY'' FERMENTS." 

 A LL who consider the meaning of words, and who desire, as 

 -'^ far as possible, to remove ambiguity from the terms 

 employed in denoting chemical change, must have felt some 

 dissatisfaction -with the nomenclature used, chiefly by physio- 

 logists, in describing and discussing the remarkable phenomena 



' In connection with this passage it is necessary to explain that at the 

 time it was written I was not aware that Mr. Poulton. in his new work 

 on " The Colours of .Animals," cites the case oi Astia vittata as affording 

 the strongest support to the theory of sexual selection ; nor did I see Mr. 

 Wallace's review of this work i.T Nature of July 24 (p. 289) until after the 

 present article had been sent to the publisher. Consequently I had no 

 means of knowing what Mr. Wallace's opinion on the point might be— 

 except in so far as his reply to Mr. Pou'ton is the only one that common 

 sense would immediately suggest to any man wlio holds Mr. Wallace's views 

 on sexual ornamentation, or who criticizes the subject without prejudging it. 

 — R. I. P. 



