74 



KNOWLEDGE 



[Aprii., 1902. 



Semper tbouj^ht. that the legs would lie developed l>y the 

 time they were wanted. Hoek inferred that some females 

 could do without them. Hoek was right so far as he 

 ventur(>d to go. A still more complete solution of the 

 enigma, which had remained unsolved for more than a 

 hundred years, was on the eve of being jmblished. In tlie 

 same year, 1877, the Italian author Cavanua announced 

 the surprising but no longer deniable fact that it was not 

 the female at all but the male on whose ovigerous limbs 

 the eggs were supported. There may be but a single 

 clump carried by the two legs in common, or on each leg 

 a packet, or several packets, or the eggs distributed singly. 



Lateral view of Chcefonymphon hirfipes (Bell) ; the walking legs 

 omitted. After Sars. 



Whatever the variations of arrangement, a large clutch of 

 small eggs or a small clutch of large eggs, or otherwise, 

 with them all it is the father that is the fostering nurse. 

 Nor does he undertake the duty in any casual way, without 

 the highly-developed preparedness that befits so tender an 

 office. Seeing that he may upon occasion be required to 

 take charge, not of twins or triplets merely, but of a 

 thousand eggs in one cargo, it is just as well that he 

 should have some appliances ready for this multiple 

 trusteeship. Now, as explained by Dr. Dohrn (" Die 

 Pantopoden des Golfes von Neapel," pp. 33, 67), in all 

 males but not in the females of the Pycnogonida the 

 fourth j<jint of the ambulatory legs is provided with a 

 gland which through apertures one or many exudes a 

 viscid secretion. Dohrn, probably with an eye to the 

 masquerading ingenuity of spider-crabs, proposes to 

 explain the use of this cement as enabling the animals to 

 coat themselves over with extraneous articles. To this 

 Hoek pertinently objects that in the economy of this 

 group adhesive patches from the outside world or dis- 

 figuring disguises of any sort are very far from being 

 coextensive with the occurrence of the glands. Besides, a 

 much better explanation is available. Since Dohrn him- 

 self specializes the glands as a masculine feature, one can 

 scarcely refrain from agreeing with Hoek's suggestion 

 that their purpose is to agglutinate the eggs about the 

 appropriate paternal limbs. Nevertheless it must be 

 admitted that in one remarkable genus to be hereafter 

 noticed, though there are ovigerous legs in both sexes, no 

 observers have yet found these legs with ova adherent to 

 them in either sex. Also in a solitary example of Nymphon 

 hrevicaudatum, Miers, Dr. Hoek found the exceptional 

 combination of highly-developed ovaries and a distinct 

 egg-mass on the ovigerous leg. The explanation of this 

 might be tliat a female specimen had casually developed a 

 male characteristic, or that a father not too seriously 



devoted to his domestic duties had for once stuck the eggs 

 on to his wife's leg instead of his own. 



Since many females retain these limbs, on which perhaps 

 in a past age they regularly carried the ova though they 

 carry them no longer, the enquiry will be made, why do 

 they still retain the liml)s without the office? The answer 

 to this is that they have an additional function which 

 explains their retention. Only, this answer does not seem 

 very flattering to the females which have given up the 

 limbs. For the function intended is that of cleansing 

 feet. For this no doubt they are as well adapted as the 

 paw of the domestic cat or as the curiously modified 

 appendages in some of the Entomostraca, which the 

 Germans have called Putzfiisee or dressing-legs. One 

 may charitably suppose that the female Pycnogonids no 

 longer possessed of this wholesome apparatus satisfy 

 decorum by employing in its stead the larger but very 

 similarly constructed ambulatory limbs. The latter in 

 this community show no averseness to the adoption of 

 anomalous functions. 



The attendance of the males on the business of the 

 nursery is susceptible, as we have seen, of illustrative 

 comparisons. Not so easily will a zoologist, by appealing 

 to common fame, detract from the uniqueness which the 

 other sex exhibits in the position of the ovaries. To the 

 thorough philosopher and to the thoroughly ignorant all 

 things are much on a level as alike miraculous or alike 

 common-place, but to the general ruck of us who know 

 just enough to derive pleasure from knowing more, the 

 discovery that eggs can be developed in a creature's leg is 

 generally when first made an exciting experience. In the 

 famous apologue by which Menenius Agrippa drew back 

 to their allegiance the revolted populace of Kome, his 

 point was that the body politic resembles the organization 

 of an animal, in which, however active and hardworked 

 and unpampered the limbs may be, they would speedily 

 lose their place and power in the 

 world, were it not for all that goes on 

 in the trunk to sustain the life of the 

 individual and secure the permanence 

 of the species. A plebeian, a prole- 

 tarian, with natural knowledge some 

 two dozen centuries in advance of his 

 age, might have answered that there 

 was no absolute need for any such 

 monopoly on the part of the trunk ; 

 that in the Pycnogonida, small 

 antmals abounding on the shores of 

 Italy, the limbs had asserted them- 

 selves and known how to reduce the 

 body to proper subordination and 

 insignificance. This at any rate is the 

 case, that in the marine animals we 

 are now considering nature has chosen 

 to follow a course different from that 

 pursued in mites or myriapods, insects 

 or crustaceans, spiders, harvestmen, or 

 scorpions. Here only, so far as at Fourth ioint of an 

 present appears, have we the intestine ambulatory limb of 

 of both sexes and the ovary of the ^fter'sar/''"''''"*'"'*' 

 female prolonged far into the limbs. 

 Many of the species have an integument sufficiently trans- 

 parent to exhibit these iutra-crural peculiarities without 

 the least pretence of prudery. Pallene brevh-ostrii!, 

 Johnston, first recorded from Great Britain but by 

 no means confined to our islands, is one of these 

 pellucid species. That the same or closely related, 

 forms have been variously named empiisa, phantoma, 

 spectrum, as though they were disembodied spirits, is 

 due to that corporeal meagreness which is more or less 



