April 13, 1899] 



NA rURE 



57, 



concerned we are indebted lo Standfuss ' for a comprehensive 

 list of the cases recognised, distinguishing between those where 

 the seasonal disparity is so marked as to have led to the 

 bestowal of distinct names on the two forms, and those where 

 the disparity is less and no second name has been given. In the 

 former category there are 23 cases (17 in Butterflies and 6 in 

 Moths), and in the latter 15 (14 in Butterflies and i in Moths), 

 making in all 38 cases, viz. 31 in Butterflies and 7 in Moths. 

 The butterflies comprised in the more marked category include 

 I case in Satyrinre, 2 cases in NymphalinK, 5 in Lycfenid.-e, 

 6 in Pierina;, and 3 in Papilionina; ; while those in the less 

 marked category are three cases in Satyrinae, 3 in Nym- 

 phalina;, 3 in Lyc;?nida;, and 5 in Pierina;, so that taking 

 the totals of both categories in their order of numerical 

 importance we have 1 1 cases in Pierinre, 8 in Lycasnidas, 

 5 in Nymphalinse, 4 in Satyrinse, and 3 in Papilionince. 

 The moths are ranked in the more marked category with 

 the exception of a Liparid {Dasyihira ahietis) ; they are 

 two in the Bombycida; and four Geometers. The number of 

 known cases in the Pala?arctic Region thus appears to be very 

 small, when contrasted with the very large number of species 

 of the groups to which they belong ascertained to inhabit the 

 region ; but it may be observed that a considerable proportion 

 of them must be of greatly extended occurrence and very ancient 

 standing, Pryer - noting no fewer than six of them in Japan (be- 

 .sides three additional cases in local species) ; and Dr. A. Fritze ^ 

 further recording in the same country the case of Araschtiia 

 levaiia (var. hurcjana). 



When we turn to the great tropical and subtropical regions, 

 where butterfly life finds its fullest and most varied develop- 

 ment, it is almost disheartening to find how extremely little 

 has been done in the observation of this apparently prominent 

 feature of seasonal variation. With the exception of India in 

 the Oriental Region, and South Africa in the Ethiopian Region, 

 none of the hot or warmer countries have hitherto received the 

 slightest investigation as regards this particular subject of bio- 

 logical inquiry. I can find no record of any observations in 

 East or West Africa, in Australia, or in Central and South 

 America. Feeling especially the deplorable lack of information 

 from that paradise of butterflies, the Neotropical Region, I con- 

 sulted Dr. F. A. Dixey with the view of ascertaining whether 

 the Pierinoe — the group which he has made so emphatically his 

 own, and which in the Old World has yielded more cases of 

 seasonal dimorphism than any other — ofi^ered any instances of 

 the kind in Central or South America. He most obligingly 

 brought together, in the Hope Department of the Oxford Uni- 

 versity Museum, a series of Neotropical species of Cai/idiyas, 

 all of which included forms corresponding in character with the 

 seasonal varieties occurring among their Old-World congeners 

 and allies, viz. a larger form, of deep or rich colouring with the 

 underside freckling and markings strongly expressed ; a smaller 

 form, of paler colouring, with the underside freckling and mark- 

 ings very faint or altogether absent ; and, in addition to these, 

 specimens holding an intermediate position between them as 

 regards the characters mentioned. Dr. Dixey exhibited this 

 series (with some additions and substitutions) at the Society's 

 meeting on December 7, and explained that, in order to meet 

 the possible objection that the variations in question pointed to 

 loial forms, he had been careful in the case of each species to 

 select examples from the same locality. The species concerned 

 were C. ritrina (Mexico), C. tieocypris (South Paraguay), C. 

 argaiite (Brazil), C. agaritlu (Mexico), C. scntiae (Guatemala 

 and Brazil), and C. //;//ta (Guatemala). There was no sufficient 

 evidence as to the seasons of appearance of these variations, 

 only seven examples (four C. argante and three C. seniiae) in 

 the whole series bearing dates of capture ; but the nature of 

 them, and the parallelism with which they were displayed by 

 each of the six species, were such as to leave little doubt of 

 their being seasonal. 



I am further indebted to Dr. Dixey for the first indication 

 of the occurrence of seasonal dimorphism in Australia, afforded 

 by the Old-World section (Catopsilia) of the same genus Cat- 

 lidryas. In one species, C. gcrgophone, from Melville Island 

 and Queensland, gradations are found quite in correspondence 



i-Schmelterlinge fiir Forscfie: 



1 " Handbuch der Palaarktiscfie 

 und Sammler," ed. 1806, p. 229. 



" " Rhopaloccra Nihonica : a Description of the ButterHies of Japan," 

 1886-88. The species named are Papitio machaon, P. xuthus, Picris napi, 

 Colias hyaUt Vanessa C.-all>um, and Polyomittatjts pklaeas. 



i Zool. Anzeiger, 1890, p. 12. Transl. in Ann. ami Mag. .Vat. Hist. 

 6), V. p. 200 (1890). 



with those observed in both Indian and Neotropical species ; 

 and the same phases are even more completely illustrated in 

 a fine series of Brisbane examples of the well-known Oriental 

 C. crocale, which lends some probability to Dr. Dixey's suspicion 

 that C. crocale and C. ponioiia (including C. catilla) will prove 

 to be .seasonal forms of one species.' 



In bringing to a close this attempt to give a general survey 

 of what has been published on the subject, I purposely abstain 

 from indulging in any speculative disquisition on my own part, 

 because, however attractive to myself such a course might be, 

 I very much doubt if, in the present very restricted bounds of 

 our knowledge, it would prove of any service to the Society. 

 To generalise or to speculate to any good purpo.se demands a 

 considerable body of well-ascertained fact as a basis, and this — 

 as my remarks have shown — is precisely what is wanting in the 

 present instance, notwithstanding the labours of the entomo- 

 logists of distinction to whom reference has been made. While 

 fully recognising that the artificial-temperature experiments 

 noted above have been designed and conducted with a skill and 

 thoroughness truly admirable so far as certain species of Paki:- 

 arctic and Nearctic Lepidoptera are concerned, it cannot at the 

 same time be denied that even in Europe very little has beea 

 done to ascertain all the natural conditions under which seasonal 

 dimorphism occurs, or to what extent it is adaptive to the en- 

 vironment ; and when we turn to the wide tropical and sub- 

 tropical regions, it is obvious that we stand upon merely the 

 threshold of inquiry. We have, indeed, from these regions — 

 thanks to such capable observers as De Niceville and Marshall 

 — some valid experimental evidence to guide us, but thi.s must 

 be very greatly added to, and the life-history of the dimorphic 

 species be worked out from many different directions, before we 

 can hope to approach to a clear comprehension of the complex, 

 problem now presented by the extraordinarily impressionable 

 and mutable lepidopterous organism. In studying the cases 

 under notice, it is impossible not to recognise that the most 

 diverse influences are at work — indications of protective and 

 mimetic adaptation, and of sexual selection as well, being com- 

 bined or contrasted with the efl'ects of varying temperatures and 

 degrees of atmospheric humidity, and with distinct tendencies 

 in the direction of reversion to ancestral characters. 



The investigation is one to tax the insight and resource of the 

 ablest and most zealous naturalists, and demands unremitting 

 and most exact observation and record, with carefully controlled 

 breeding from the ova for many successive generations, during 

 a considerable series of years. I am as fully persuaded now as 

 I was on the occasion of my last year's address, that such re- 

 searches as these can never be satisfactorily prosecuted, and 

 still less brought to any interpretation of permanent scientific 

 value, without the establishment in tropical countries of fitly 

 equipped biological stations for the special observation and 

 study, under as natural conditions as possible, of the surround- 

 ing terrestrial fauna. It is unnecessary to dwell upon the mani- 

 fest advantages attendant on well-directed work pursued steadily 

 and continuously in such a zoological observatory, planted in 

 the very midst of the abounding forms of tropical life, or to do 

 more than mention the exceptionally favourable opportunities 

 for discovery that would thus be afforded. In conclusion, 

 therefore, I will simply express my firm conviction that from a 

 few well-organised stations of this kind, on carefully chosen 

 sites in the four great tropical regions, science would gain more 

 in ten years than from the casual and incomplete observations 

 of ordinary collectors and travellers for the next half-century. 



THE PROGRESS OF TECHNICAL 

 EDUCATION. 



•yHE eleventh annual report of the National Association for 

 ■'■ the Promotion of Technical and Secondary Education is 

 filled with details concerning the systemisation and extension of 

 educational work during last year. A few extracts from the- 

 report will show that satisfactory progress was made. 



1 C. Cfocale is an e.\tremely variable and very widely distributed butter- 

 fly. Mr. de Niciville (Gazetteer 0/ Sikkiin, 1894, 'p. 166 ; and fount. 

 Asiat. Soc. Bengal, Ixiv. ii. p. 490, 1S95) considers that C. catilla cannot 

 be held a distinct species from C. crocale, all the supposed distinctive char- 

 acters proving quite inconstant, and breaking down when lar^e numbers 

 of specimens are compared. But he does not think seasonal dimorphism, 

 comes into play here, " the innumerable varieties which are found in bothj 

 sexes occurring at all times." 



NO. 1537, VOL. 59] 



