EX LIBRIS Wilham Healey Dall Division of Mollusks Sectional Library Q a ta i 5 ee ie aes f 7. fa, pM shale a} res er Ss | om iat J i AL Aad fy Yr : es |e jay ; Ny ee } on ae wa P| i. id 7 - ots x3 cee a) one 7 o ; PA so tie re % i ‘ae an ‘ yA a =e ; Fs ‘ ' i Vie | iy iy KH 266 Division of Moers: = EVOLUTION, _ Betesttonap meeclAL AND HABIFUDINAL. BY Rev. JOHN T. GULICK. WASHINGTON, D. C.: PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON. AUGUST, 1905. CARNEGIE INSTITUTION OF WASHINGTON. PuBLICATION No. 25. PRESS OF GIBSON BROS. WASHINGTON, D. C. NOVEMBER 10, 1905.] Dr. C. Harr Merriam, Washington, D. C.: ‘Basket Cave Burial in California.’ Discussed by McLeod, Putnam. Mr. H. N. Rust, South Pasadena, Calif.: ‘The Obsidian Blades of Northern California.’ Dis- cussed by Putnam. Mr. 8. A. Barretr, University of California: asket Designs of the Pomo Indians.’ Discussed by C. H. Merriam. Dr. P. E. Gopparp, department of anthropology, University of California: ‘ Mechanical Aids to the Study and Recording of Language.’ Discussed by Putnam. Dr. J. C. Merriam, University of California: “Some Suggestions concerning the Origin of the Calaveras Skull.’ Illustrated with lantern slides. Discussed by Hill-Tout. Mr. CHARLES KEELER, Berkeley, Calif.: ‘ Crea- tion Myths and Folk Tales of the Manua Islands, Samoa.’ Discussed by Dixon. Mr. J. T. Goopman, Alameda, Calif.: ‘ The Maya Dates.’ Discussed by Putnam. eNO,” C WILLOUGHBY, assistant curator, Pea- body Museum of Harvard University: ‘ Specimens in the Peabody Museum collected by the Lewis and Clark Expedition.’ Mr. H. N. Rust, South Pasadena, Calif.: ‘ Ex- hibition of Implements from San Nicolas Island, used for Cutting and Working Shell Ornaments.’ Proressor Howard Swan, Imperial College, Peking, China: ‘A Systematic Arrangement for Recording Dialects.’ Proressor W. H. Hotmes, Washington, D. C.: * Antiquity of Man in North America.’ by Putnam, Peabody, Swan. Dr. F. C. Newcomes, Victoria, B. C.: ‘ Exhibi- Discussed Discussed tion of Northwestern Indian Designs.’ by Hill-Tout. BY TITLE. Mr. CuHartes F. Lummis, secretary of the Southwest Society, Los Angeles, of the Archeolog- ical Institute of America: ‘ Old Indian and Span- ish Folk Songs of the Southwest.’ Illustrated with phonograph records. Mr. C. P. Mackiz, Englewood, N. J.: ‘A Plea for the more Critical Use of History in Anthro- pological Research.’ Dr. GEORGE GRANT MacCurpy, Yale Univer- sity: ‘Eoliths from England and Belgium.’ Dr. C. Harr Merriam, Washington, D. C.: * Basketry of California Indians.’ Dr. ALBERT ERNEST JENKS, chief of the Ethno- logical Survey of the Philippine Islands, Manila: “The Peopling of the Philippines.’ SCIENCE. 593 Dr. A. L. Krorper, University of California: ‘Indian System of Consanguinity in California,’ Miss JEANNE ELizaBetTH WIER, Nevada State University: ‘The Washoe Indians of Nevada.’ Dr. N. B. Emerson, Honolulu, Hawaii: “ In- troduction to ‘ Unwritten Literature of Hawaii.’ ” Mrs. ZevIA Nurrann, director of the Crocker researches in Mexico for the department of an- thropology of the University of California: ‘The HKarliest Historical Communications between Japan and Mexico, from Original Documents pre- served in Archives of Japan, recently brought to Light by a Mexican Diplomat.’ Mr. Atvin SEALE, Leland Stanford Junior Uni- versity: ‘Ceremonies relating to Sickness and Death in the Solomon Islands.’ Miss Auice C. FLeTcHER, Washington, D. C.: ‘The Harth Lodge and its Migrations.’ Mr. JAMES Mooney, Washington, D. C.: ‘ The Cheyenne Indians.’ Mr. JAMES Mooney, Washington, D. C.: ‘ The Caloosa Tribe of Florida.’ Dr. J. R. Swanton, Washington, D. C.: ‘ The Social Organization of American Tribes.’ Proressor W. H. Hotmes, Washington, D. C.: “Architecture of the Aborigines of North America.’ Proressor W. H. Hotmes, Washington, D. C.: “Use of Copper by the Aborigines of North America.’ ; Proressor W. H. Hotmes, Washington, D. C.: ‘ Problematical Objects in the Prehistoric Archeol- ogy of North America.’ It was voted that no program be pro- posed for the meeting of the American Association for the Advancement of Sci- ence, at New Orleans, and that the annual meeting be held at Ithaca, New York, in December, 1905. GEORGE GRANT MacCurpy, Secretary. YALE UNIvEeRSITY MUSEUM, NEw HAVEN, CONN. SCIENTIFIC BOOKS. Evolution, Racial and Habitudinal. By the Rev. Joun T. Guuick. Washington, Car- negie Institution, August, 1905. 8yo. Pp. xii + 269; 3 pl. Dr. Gulick for more than thirty years has been an earnest advocate of the importance of segregation of groups of individuals as an 594 element in the evolution of specific types. His papers have been useful in putting a needed emphasis on a factor which had been insufficiently taken into account and _ fre- quently overlooked by theorists concerned with the question of specific evolution. It was appropriate, therefore, that the Carnegie Institution should give him the opportunity of presenting in one handsome volume, the ripened result of his years of reflection and study on this subject. It is known that his studies were largely due to the interest excited by the beautiful and multiform tree-snails of the Hawaiian Islands, which, for variety in characteristics elsewhere usually taken as of specific value, are unexeelled in any equal area. It was a problem which appealed to every collector of these attractive How should this almost infinite variety under almost identical conditions be accounted for? The latest in- vestigations indicate that the chief food of the arboreal Achatinellas consists of fungoid mycelium which in the warm air and con- animals. stant rains of the mountainous region of the islands is more or less abundantly developed on the bark of trees and shrubs upon which these landshells live; an examination by Mr. Cook of many stomachs has shown that the leaves of the shrubs or trees form no part of their diet, and that, contrary to the opinions formerly held and even not altogether dis- carded in the volume under review, the species of tree upon which these animals live is not of importance in their economy; the same species of shell being often found indiffer- ently upon different species of trees over the area the former This fact lends even greater importance to the remaining ele- inhabits. ments of the environment among which the stimulus to variation is to be sought. It has been found that the Achatinellas do not lend themselves readily to experiment. Removal, even when not the slightest injury has been inflicted, usually proves fatal, from It is evident that they are extremely sensitive to even minute some unexplained cause. changes in altitude, moisture, ete., and at- tempts to get them to breed in the more ac- cessible regions of the islands, where they SCIENCE. [N.S. Vou. XXII. No. 567. could be kept under continuous observation, have so far proved failures. Even the eggs seem unable to bear transportation. For the reader who wishes to gain quickly an idea of the hypothesis maintained by Dr. Gulick, we should suggest the original papers of which a bibliography is given in the pres- sent volume, as they contain the meat of the matter in more concentrated form. In the opinion of the reviewer something has been lost by the considerable expansion of verbiage to which the statement of the hypothesis has here been subjected. But doubtless the special student of these recondite problems will find the volume none too long. In any event it should not be forgotten that while Dr. Gulick’s views seem eminently probable and in the re- viewer’s mind go far toward accounting for many of the facts, nevertheless they are theoretical and have not yet been subjected to the crucial test of experiment, by which the proposed theory in the end must be tested. To justify final acceptation an hypothesis must not only be capable of accounting for the facts but it must be shown to be the only one by which they may be adequately ex- plained. It .is also necessary to determine how far the animals in question have arrived at that state of organic equilibrium which we recognize by the name of species. If, as has been held by some authorities, the small color- groups are really only of a temporary nature, and lable to immediate change upon subjec- tion to modified environment, then the au- thor’s hypothesis, while losing nothing of its truth, is not a contribution to the evolution of species so much as to the physiology of color-variation. The latter may or may not be, in the group discussed, a factor of specific weight. In any case we are grateful for the full pres- entation of the author’s views which are of acknowledged importance in the discussion. The volume is well printed, though we could have wished that the colored plates had been of a better quality. W. H. Dat. Marceli Nencki Opera Omnia. Gesammelte Arbeiten von Professor M. Nencxri. Braun- schweig, Friedrich Vieweg und Sohn. 1905. ¢ PRE PAGE: In the present volume I have brought together in one connected presentation the chief results of my investigations concerning the factors of organic evolution. Portions of my theory of divergence which were published in the Linnean Society’s Journal are repro- duced in the Appendix, with careful revision; but the fullest exposi- tion of the fact that all evolution, as we now observe it, is divergent, and that other factors besides natural selection are absolutely neces- sary both for the origin and the continuance of this divergence, is given in the new chapters constituting the body of the volume. These chapters have been written while considering the most recent biological investigations bearing on the general theory of segregation. The first four chapters of the volume are introductory, in that they present many facts of divergence and distribution in both natural and domestic species, which remain complete enigmas till the forms of racial and habitudinal segregation have been fully recognized. Chap- ters V, VI, and VII present the fundamental laws of segregation, and the interaction between the different classes of factors—between isolation and selection, between racial segregation and habitudinal segregation, between autonomic factors and heteronomic factors. In Chapter VI, § II, 14-17 (pp. 101-111), will be found a fuller ex posi- tion than has been presented, in any of my essays published by the Linnean Society, of the tendency of certain combinations of partially segregative endowments to become more intense in successive genera - tions. Itis shown that this is especially the case when endowments, tending toward the mating of like forms with each other, are reinforced by varying degrees of mutualinfertility and incompatibility between unlike forms. Appendix II, $ IV, 3 (pp. 241-243), briefly indicates several methods of constructing what I have called the permutation triangle. It was first constructed in order to show that the sterility of cross-unions between divergent forms (whether they be varieties, species, genera, or higher groups), would lead rapidly to the extinction of most of these forms, if instincts and other endowments did not facilitate the union of compatible forms. The table thus constructed is found to be a concise presentation of certain classes of probabilities that arise in the pairing of things by chance. ili iv PREFACE. The principles molding segregation, and so controlling variation and heredity, and the effects on racial and social evolution produced by such control, are presented with considerable fullness of illustra- tion on the biological side. For my purpose it did not seem necessary to dwell at equal length on the social aspects. Another broad department of the subject is referred to in only the briefest way. ‘This is the effect of amalgamation or regressive segrega- tion, both racial and social. I have, however, pointed out that in the history of man segregation was the leading factor through countless generations when races, languages, and institutions were becoming increasingly subdivided; and that it is only in modern times that the barriers to free intercourse have been so rapidly yielding that regres- sive segregation has been the predominant feature in human history. I have presented evidence that, even in the case of invertebrate animals, members of the same species, exposed to the same environ- ment in isolated groups, will often arrive at divergent methods of dealing with the environment, and so subject themselves to divergent forms of selection. If my contention is in accord with the facts, the assumption which we often meet that change in the organism is controlled in all its details by change in the environment, and that, therefore, human progress is ruled by an external fate, is certainly contrary to fact. It is of no little interest that the recent developments of biological science, in both Europe and America, are pointing, not only to the power of the organism to deal with the same environment in different ways, and so to determine the forms of what I have called active (or endonomic) selection, but also the power of many animals to deal with sudden changes in the environment in such a way that the group is saved from extinction till ‘‘cozncident variations’’ have time to arise, insuring completer adaptation to the new conditions through selection. The teachings of biology are thus coming more nearly into accord with that school of sociology which has for years maintained that the social group may learn to determine the form of its own social evolu- tion. We are thus led to hope that man will in time determine his own evolution, racial as well as social; for when sufficiently advanced to realize the breadth of the responsibilities resting upon him, the form of his racial inheritance will naturally be determined by the ideals shaping his social organization. In the third chapter, and again near the end of the last chapter, attention is called to the fact that, in accommodational and anticipa-. tory action, and in codéperation for the attainment of future results, all forms of life, from the earliest protozoa till we reach the highest PREFACE. Vv types of spiritual life in man, present activities entirely unknown in the inorganic world. In the degrees of attainment reached in codpe- rative action (with the division of labor and community of interest), and in anticipatory and discriminative action (securing adaptation to future conditions), we find a definite test of the stages of evolution reached—a test that is applicable to the lowest as wellas to the highest living creatures. Of my papers previously published, the one on Divergent Evolution has received the most attention. This is perhaps due to the fact that it was not only published in London in the Linnean Society’s Journal for 1887, but was reproduced in this country in the report of the Smithsonian Institution for 1891. I wish, however, to emphasize the importance of the factors enumerated and illustrated in the one on intensive segregation (see Appendix II). If we would fully com- prehend the factors producing the segregation of organic types, we must recognize not only the forms of isolation by which groups are first set apart; but also the physiological and psychological forms of segregation by which the slightly divergent forms are held perma- nently apart, and still further, the factors producing divergence in these isolated groups, and so resulting in intensive segregation. I show that intensive segregation is due not only to the exposure of isolated groups to different environments, but also to the different methods of dealing with the same environment adopted by the iso- lated groups. I also point out other factors that are subject to change without any change in the activities lying outside of the species; and all such I class as autonomic factors. Throughout all the chapters the underlying purpose has been the investigation of the autonomic as well as the heteronomic factors controlling evolution. The chief hindrance to the increase of our knowledge of the method of evolution is the tendency to regard some one of the several prin- ciples influencing segregation as the one principle controlling the whole process. I believe Prof. H. F. Osborn makes no mistake when he suggests that the ruling method of the next important advance in the interpretation of evolution must be one recognizing the complex action of diverse principles, and at the same time grasping the under- lying unity of the process. In the present volume the question is raised whether segregation, with its controlling influence in the spheres of both racial and habitudinal evolution, is not the underlying principle we are seeking. It must, however, be carefully noted that segregation as defined in this volume covers a much wider sphere than isolation. In order to reach the more pronounced results of racial segregation, the separate groups produced by isolation must vi PREFACE. for several generations be subjected to divergent forms of selection ; and in all the forms of animal life that are capable of learning by experience, accommodation, controlled by the principles producing habitudinal segregation, is constantly guiding and shaping racial segregation. Though more familiar words have been chosen for the title of this volume, the subject here treated would have been clearly expressed if the title had read: ‘‘Habitudinal and Racial Segregation; or, the origin and intensification of organic types, guided by innovation and tradition acting under segregate association, and established by variation and heredity acting under segregate intergeneration.” Joun T. GULICK. OBERLIN, OHIO. CONTENTS: CHAPTER I.—INTRODUCTION. Pieenealar dori x planation: 2h vcs. kee eee eek oueb lee se Small Areas of Distribution for Species of Hawaiian Snails......... MME MLeTarading Of SMecies: »as)45 saree oe evans s akhae > © be 3 Selection not Always the Cause of Divergence ..............----.---- In Many Cases Sexual Selection not the Cause................... In Many of the Same Cases Natural Selection not the Cause........ May not the Prevention of Free Crossing be an Explanation............ Investigation of Causes and Effects of Segregation.......+..........-- Segregation the Unifying Principle in Evolution..................... CHAPTER II.—Brionomic LAws. Meth octorginvestigacionm crepes. cece ereters rein eee kv oheiistaiteuay te a) es SCOMCIOMELOMOMIM CS Hasty ya tea Tats ae asa tiaye Coes als red ven le veleyera\trfe tele, ays Why we Commence with the Method of Evolution................ Neediotinvestication ofallehactors: . 4298. sees ss aoe cles =. Natural and Sexual Selection not the Only Factors............... Comparison of Conditions in Natural Species and in Domestic Varie- SUES Shey ha Sisvbea et dis BYE Gro ends Bere Moai Ce ona tO a hae ear Dive ny enCenoimicCeSs arabe resent nity fers Siaielatees = levers syscnllete) anes oe +388 Siigilonl Mis? OT IRAKERS., 2G Bye ole o eras eyeraee oz Eb act BIR IO. Stover oRatOln Dace tone Amalgamation of Races............. ESE VA sre aM nt Sasha, coe Coe T A oilsas exe se Influence of Acquired Characters on Racial Characters............ CHAPTER III].—THE EVOLUTION OF NATURAL SPECIES. eri ee sta GGHLU? cerns Se AY oon fay 5 duoc tach and Ufa ... 6. 20d ee eee cel. 129-131 Reversal of Partition and Isolationin Man...................... 130 Isolation Prevents Reflexive Selection between Groups........... 131 Discriminate and Indiscriminate Action of Principles................. 132-136 etre stot MBE UNCEION Lon fs 6: 5: sies as dialed Ae Je es 132 pirabccetacnieaete ASTIOM 5/5 sec. 3's fe po Ue Ee ee 133 Porerasrsmiee Hetty ACMON ce 5.54 Soe eect 134 Table of Discriminate and Indiscriminate Modes of the Four cE ETS) ES AN AT AEE a4 eR Ss (1 136 xX CONTENTS. CHAPTER VIII.—CLASSIFICATION OF THE FORMS OF THE PRINCIPLES PRODUCING ALLOGAMIC EVOLUTION. ‘Tables of Porms) with Brief Explanations! )43-).44:4)seueiien Ae 137-141 Allogamic, Autogamic, and Agamic Evolution................... na Forms of the Four Principles of Segregation............. pian aie Ee 138 FormsrofSelection Defined 474.08 oe rice ee eee 139 Conditions Determining Forms of Selection ..................... 140 Autonomicanditeteronomie Intinences errs rae eee eee 141-144 Autonomic Influences Include Endonomic and Reflexive.......... I4I Autonomic Partition Produces Autonomic Isolation.............. 143 / Na Ohanyevorchal ACA bboNOO iso gin en sooesceiadsdoooodsonones BSeerrete 144-145 CHAPTER [X.—SUMMARY AND CONCLUSION. Stmmayercoaess = : gd sds els alae cash «ea eho anshgen Mael cae RTA Cen 147-153 Segregatiome. 2) ).5).cccieaiere ee, abehauctale/b geese iyenc kere ane cele a eet pa tea 147 UnbalancecdtiPropagationiers ar meres oie eee 148 Cumulative Effects through Codperation of Different Principles... . 150 Through the Operation of Same Principle in Successive Gene- FATTOMS |oh diver toktssot even ae eee e Rane aoe eee 150 PNT geM ATION. 0S aso 9 Siass os co ae Elo ee a eNO CONE ee pcan eer ac eae 151 Some of the Facts Emphasized in this Volume................... 151 Goneltsiony es ny A 0 Eos iach 2 nn ea gay ae Rega 153-158 What has been Gained by Recognition of Habitudinal Segregation . 153 Methods of Study that Should be Fully Applied ................. 153 Study of Organisms under Conditions Favoring Segregation. ...... 154 Prediction Confirmed by Partula of Walitic 2. 7a2) esse 155 Power of Organism to Control its Relations to Environment In- creases with Stage of Evolution Attained..................... 156 Chief Method of Advance is Tentative Variation with Transmission to|Ofispring of Endowments of Sirvivers.. 5502 0c. . e e ete 157 Three Spheres of Progressive Adjustment—Accommodation, Co- Operation ang ANtIeTPAtIOM. 52 ace ye ys opie. ce ety ae ere 158 Increasing Recognition of Autonomic Factors................... 158 AppENDIX I.—A SMALL PORTION OF DIVERGENT EVOLUTION. {From the Linnean Society’s Journal, Zoology, vol. xx.] Reflexive Segregationy.. tai aig) s ida eee a cre en ienea, Oeer ara eae 159-174 Conjunctional Segregation. 0.770 oan. aoe ee cee eee 159 Social, Sexual, Germinal, and Floral Segregation ............ 160-163 Impregnational Segregation... 0. 22H eos cas sr eee 163-171 Negative and) Positive Seprepatiom.04)..)5 2. S yen te 163 Dimensional and Structural Segregation.................... 165 Potential Sezregation: “./).085. setae recientes ee eet 166-170 Tnstitutional'Sepregation. ¢. 202 oe. eon ae mba eed hae neon eer 171 Concluding Remarks: Impregnational Segregation in Earlier and Later Stages........... 172 CONTENTS. xi Concluding Remarks—Continued. Isolation Usually Discriminate and therefore Segregative from the Piste ee Ocha. TN ta cotes eh eee em eee ee. oeu htt 174 Intensive Segregation put in the Next Paper..................... 174 anieiol forms of Segregation: ; STi e re ea th eee ire 176 Computation of Effects of Positive and Negative Segregation... ... 177-183 IUD G15) U1 MAAR a ds Phra Meaba bir, Il Ak ert ooo A. Ue ini 179 RADE RVGR CN nets os SL: Lene Sire NE eR ee ee 182 APPENDIX II.—INTENSIVE SEGREGATION. {From the Linnean Society’s Journal, Zoology, vol. Xx1it.] Classification of the Forms of Intensive Segregation.................. 185-212 Separation Always Involves More or Less Segregation............ 186 Hight Principles of Monotypic Evolution....................... 187 Certain Laws of Growth not here Discussed..................... 189 The Transformation of Freely Intergenerating Organisms never Bemucmentiy wD iKeneetibe Verws Mubh,) she). cua obey gach eae de we missin Ig! Independent Transformation Always Divergent................. 19I Pervasive Influence of Causes of Transformation.................. 192 Utilitarian and Non-Utilitarian Divergence..................... 194 peleciional Intension/and Its Forms, ..0.. 00.50... . se lb beccels 195-207 Inidiscriminate Eliminational Intension.........:..-:....0.+..... 209 Pumaleamanonal IMtenStonl so. ok. ea sal rladd oes eet see ren, 211 Combined Influence of These Principles...............00..4 0500 212 DE ESEN SS TV OULU oie NA he rae Cn 212-224 Divergent Evolution in the Snails of Oahws.................+..% 2-220 Similar Facts Concerning Land-mollusks of Other Regions......... 224 MODs eae MAO TAD 1 oe OU I sacle Ys fobs 0.2} Sagas d 024i Rind alec oe dion 225-234 Divergened im Mrynmis and Thanaos).. oc... 556. got ae anes s 225 DHiviermemispectesio@l, BaSilatGhia. 2p... 6s vn drtnlae vim ode deletes 225 Diversence im the:Periodical Cicada... cide. save boca cc eee 229 SOUT GUE IRrre aie ON ae ee 234-243 Outline of the Argument in Support of Divergence through Cumu- JENESTE |S SURE EE LO) a eed eo el ea ee Pea re 234 Reece AGL SEENON “ors dp. sini2'd!s gant s dom sie Gee Modle OAR ie Oe 236 Coustmetion of Permutational ‘Triangle. .... 0.50.2. bya es bs os 241 APPENDIX III.—LETTERS. [Published in “‘ Nature,”’ April 10, May 8, and August 14, 1890, and April 1, 1897.] “Like to Like”’ a Fundamental Principle in Bionomics ................ 245-249 Wiis ERED EME e816 Mo a's, aise: +, ace spa oa Seen RAE FEM tees bo 249 Local Segregation Often Initiates Divergence.................... 247 Permanent Difference in Innate Adaptations not Necessarily Ad- WmmeomivMNfetenee 5.5... osc 5.510 Lee eee 248 Unstable Adjustments as Affected by Isolation........ RSC iin eye 249-252 Indiscriminate Separation, Under the Same Environment, a Cause of PER eUnE remem mete SP. eres Ruth RUA g MEE CI ae otra. 252-255 Xi CONTENTS. Indiscriminate Separation, etc., a Cause of Divergence—Continued. Faetis, Proving Pints). 2 seo. unis 2, sure oe eed ee tacte ae eet ene em 252 Cessation of Reflexive Selection Between Isolated Sections Causes Divergence as Soon as Heredity Weakens...... PA Se cas se SMe 254 UtilityrofSpeetie Characters. oy Feat ee er careeeye eee e A e 255-261 Right-handedness, Left-handedness, and Similar Differences....... 256 Difference in Use not Necessarily Useful Difference ............... 258 Divergence Due to Different Methods of Reflexive Selection Often Noneadvanita cease. S = the majority are dextral; S >> D = the majority are sinistral; S — Ba = sinistral with the exception of about 1 in 500. NOTES ON THE SPECIES. Fic. 1. Carelia cocklea (Rv.) D. From the island of Kauai. Examination of the organs will probably place it with the Achatinellide. Fic. 2. Amastra nucleola (Gould) D. From Waiole, Kauai. Fic. 3. Auriculella auricula (Fer.) D > S. This species, like others of this genus, is found on the leaves of trees and shrubs. Its habitat is the eastern por- tion of the forest region of the island of Oahu. ‘This specimen is from the valley of Palolo. Fic. 4. Apex apicatus (Nwe.) D > S. From Wahiawa, Oahu. Also found in Helemano and Ahonui. Fic. 5. Leptachatina fumosa (Nwe.) D. Found on the ground under dead leaves, in damp forest regions from Nuuanu to Palolo, on the island of Oahu. This specimen is from Palolo. Fic. 6. Laminella sanguinea (Nwe.) S. Found in Helemano and Wahiawa and the intervening regions on the island of Oahu. This specimen is from Helemano. Fic. 7. Laminella citrina (Migh.) S. From the island of Molokai. Fic. 8. Laminella tetrao (Nwe.) S. From the island of Lanai. Fic. 9. Laminella venusta (Migh.) S. From Lahaina, West Maui. Fic. 10. Laminella bulbosa (Gk.) S. From Kula, East Maui. Fic. 11. Partulina dubia (Nwe.) D. This is a rare species distributed over a number of valleys of the island of Oahu from Waianae to Kalihi. This specimen EXPLANATION OF PLATE II. 39 is probably from Kalihi. No other species from the Hawaiian Islands seems to so closely resemble the Partula found on many of the islands of the Pacific. Still it must belong to the Achatinellide, for it completely intergrades with Partulina densilineata, which presents the peculiar twist of the columella, the most constant shell-character of the Hawaiian family of snails.* Fic. 12. Partulina virigulata (Nwe.) D>>S. From the island of Molokai. Fic. 13. Partulina variabilis (Nwe.) S. From the island of Lanai. Fic. 14. Partulina splendida (Nwe.) D> S. From Lahaina, West Maui. Fic. 15. Partulina plumbea (Gk.) D. From Kula, East Maui; found on the trunks of trees several thousand feet above the sea level. Fic. 16. Newcombia cumingii (Nwe.) S. From Makawao, East Maui. Fic. 17. Amastra turritella (Fer.) D. Found on dead trees from Waiawa east- ward to Keawaawa, island of Oahu. This specimen is from Palolo. Fic. 18. Amastra violacea (Nwe.) D. From the island of Molokai. Fic. 19. Amastra magna (Adams) D. From the island of Lanai. Fic. 20. Amastra mastersi (Nwe.) D. From Lahina, West Maui. Fic. 21. Amastra nigra (Nwe.) D. From Kula, East Maui. The Darwinian theory explains the unity of form in the different genera and species of one family by the theory that they are all de- scended from one original intergenerating stock. The diversity in the forms is explained as the result of variation, with diversity in the forms of selection produced by exposure to different environments. In explain- ing the divergence in the genera of this family, I think, we shall come nearer to the facts if we attribute the diversity in the selection, to which they have been exposed for countless generations, to diversity in the methods of using the environment adopted by completely isolated groups. The divergence in many of the closely related species, found on the same species of trees in successive valleys on the same moun- tain range, is, I think, due to 1solation and variation, without any dijfer- ence in the forms of selection. 7 EXPLANATION OF PLATE II. This plate presents 25 species of Achatinella, a genus of arboreal snails found on the island of Oahu, and most of them confined to dis- tricts from 1 to 3 or 4 milesinextent. Achatinella is one of ten genera of the Achatinellide, of which there are between 200 and 300 species and over a thousand varieties, on this island only 40 miles long. Hight of these genera are given on Plate I, andoneon Plate III. This plate illustrates the relationship of species distributed in different valleys on the same island. The letter attached to each figure desig- nates the valley or small district in which the specimen figured was found. The position of this valley or district on the island is easily * A careful comparison of the internal structure of this species with the struc- ture of the Partula of the South Pacific might perhaps reveal points of special interest in the relations of the two groups. 40 DIVERGENCE UNDER THE SAME ENVIRONMENT. discovered by reference to the map of Oahu preceding Plate II, where the same letters are used to designate positions. It will be observed that underscored letters are used to designate positions on the north- east side of the main mountain range, and that Roman letters are used to designate the positions on the southwest side of the same range. These are so arranged that the valleys indicated by the two forms of any one letter are nearly opposite to each other. The twenty-five species presented in this plate would have to be considered as one species if we accepted the statement that the find- ing of completely intergrading forms between two types proves that they are varieties of the same species. If, on the other hand, we adopt the statistical method of testing species,* these, and many more found in the forests of the same mountain range, will have to be classed as species. The collection of the species and varieties of this genus, made by me from 1850 to 1852, present a complete series of intergra- dations between the larger forms found on the trunks of the candle- nut tree in the eastern valleys of Oahu, and the small forms found on the leaves of the lobelia and other shrubs in the western valleys of the island, where groves of the candle-nut tree abound, occupied more or less by species of Bulimella, but neglected by the representatives of the genus Achatinella. As no one will maintain that these most diver- gent types of the genus belong to the same species, the existence of such a series of intergrading links becomes a strong argument for the belief that divergent forms properly ranking as species have arisen from one original species, through the cumulative effects of variation coéperating with a series of isolations, each isolation lasting for many generations before the next occurs. The genera most characteristic of Oahu are Achatinella, Bulimella, and Apex; for, with the exception of two or three species of Achati- nella found on the island of Molokai, they are limited in their distribu- tion to this island. ‘Their distribution in the different districts of the island is probably due to the adaptation of Bulimella to a damp cli- mate, and of Achatinella to a region of dense shade, but of less rain, and of Apex to a comparatively dry climate. As regards rainfali, the northeast side of the main range catches the trade winds as they come from the ocean, and receives the heaviest fall; on the southwest side of the same range there is less rain; and on the shorter range, on the southwest side of the island, there is still less rain. In the first region we find Bulimella and a very few Achatinella; in the second region * The explanation of Plate III brings out the fact that the individuals represent- ing intermediate forms are very rare compared with those of typical forms. Such species meet the statistical test. EXPLANATION OF PLATE III. 41 both Bulimella and Achatinella in the shady valleys, with Apex on the comparatively sunny ridges; and in the third, several abundant species of Apex, and but one species of Bulimella, and but one of Acha- ‘tinella, both of these being extremely rare. NOTES ON THE SPECIES. Fic. 1. Achatinella zonata (Gk.) S. From Pupukea. Fic. 2. Achatinella albescens (Gk.) S. From Pupukea. Fic. 3. Achatinella recta (Nwe.) S. From Kawailoa. Fic. 4. Achatinella herbacea (Gk.) S. From Kawailoa. Fic. 5. Achatinella delta (Gk.) S. From Wahiawa. Fic. 6. Achatinella rhodorhaphe (Sm.) SS. From Wahiawa. Fic. 7. Achatinella pygmea (Sm.) S$. From Ewa. Fic. 8. Achatinella ligata (Sm.) D. From Ewa. Fic. 9. Achatinella analoga (Gk.) S. From Halawa. Fic. 10. Achatinella colorata (Rv.) S. From Halawa. Fic. 11. Achatinella adusta (Rv.) S. From Pauoa. Fic. 12. Achatinella castanea (Rv.) SS. From Pauoa. Fic. 13. Achatinella olivacea (Rv.) S. From Pauoa. Fic. 14. Achatinella dunkeri (Cuming) S. From Makiki. Fic. 15. Achatinella producta (Rv.) D >S. From Makiki. Fic. 16. Achatinella buddii (Nwe.) S. From Makiki. Fic. 17. Achatinella johnsonii (Nwe.) S > D. From Manoa. Fic. 18. Achatinella stewartit (Green) D> S. From Manoa. Fic. 19. Achatinella fuscozona (Sm.) S. From Manoa. Fic. 20. Achatinella trilineata (Gk.) S. From Palolo. Fic. 21. Achatinella varia (Gk.) S— D a From Palolo. Fic. 22. Achatinella bacca (Rv.) D. From Palolo. Fic. 23. Achatinella plumata (Gk.) S. From Waialae. Fic. 24. Achatinella diversa (Gk.) S. From Waialae. Fic. 25. Achatinella abbreviata (Rv.) D. From Waialae. EXPLANATION OF PLATE III. The purpose of this plate is to illustrate the variations and inter- grading forms of closely related species of the Achatinellide. The 25 shells figured in this-plate are found in the northwestern portion of the island of Oahu, and are regarded as belonging to four species, of which Bulimella ovata Nwe. is presented under ten variations, five being of the dextral form (see figs. 6 to 10), and five of the sinistral form (see figs. 11 to 15). Of these figure ro is found in Hakepuu, and the rest in Kahana. Figures 1 to 5 are of Bulimella bulimoides Swn., found in Kawailoa; figures 16 to 20 are of Bulimella obliqua Gk., found in Kahana; figures 21 to 25 are of Bulimella rosea Swn., of which figures 21 to 24 are found in Wahiawa, and figure 25 is found in Helemano. Intergrading forms are found between figure 5 of this plate and Bulv- mella glabra Nwe.; between figure 8 of this plate and Bulimella ojmor- pha Gk.; between figure 15 of this plate and Bulimella rotunda Gk. 42 DIVERGENCE UNDER THE SAME ENVIRONMENT. The relative numbers in which these different variations occur are roughly indicated in the following table, in which the numbers not inclosed in parentheses correspond with the figures in Plate III, while the number in parentheses below each one of these indicates approxi- mately the relative frequency in which it was found. I 2 3 4 5 6 7 8 9 10 II 12 13 (200) (150) (100) (60) (30) (200) (200) (200) (200) (100) (200) (200) (200) I 15 16 ey 18 19 20 21 22 23 24 25 (100) (60) (1) (200) (200) (200) (60) (30) (300) (45) (15) (15) The metropolis of Bulimella rosea is Wahiawa, where the most abundant type of coloring is seen in figure 22, which is snowy white with a pink lip. In Helemano district, the shells of this species are somewhat smaller, with the lip more frequently white, and the body of the shell not as snowy white as is usually the case in the metropolis. Figure 21 isa comparatively rare variety of B. rosea, white throughout and intergrading with B. ovata through a nearly white variety of the sinistral form of that species, occurring in Kahana in the proportion of perhaps one to a thousand of the normal specimens of the species. Again, in figure 16, we have a very rare form connecting Bulimella obliqua with Bulimella ovata. OAHU THE METROPOLIS OF THE ACHATINELLIDA. The island of Oahu may be regarded as the metropolis of the Acha- tinellide, for on this island we find 8 of the ro genera, while on Maui and Molokai together we find 7 genera, and on Kauai 3 genera. Suf- ficient attention has not been given to the land snails of Hawaii to enable us to give a full report; but I am told that there is an unusual development of Succinea on that island, while the Achatinellidz are but very meagerly represented. One explanation of the small devel- opment on the island of Hawaii of the family of snails which is so fully developed on the island of Oahu is found in volcanic eruptions, which on the island of Hawaii have from time to time destroyed the forests till recent years; while on the island of Oahu it is probably hundreds of thousands of years since such complete destruction of the necessary conditions of existence for these creatures has occurred. "Ve ae ML deve, 9 rate \ * i ip VES al yee en a! & 2 hanes and ei ota ak whurigeey . is ohe Vepaltat or mental do bret alae acsionsiameeaeiad ee aa =f ' Sed i PR ten ae RS an . af 1M) ! i { i , i 4 ' i a / y : i! ayy PTA ear ; \ ) i J F fy i iy By) ‘\ i Y ib F i i \ i a wt ee A Ait) ; pa! it | ire GULICK PLATE III 248 21g 228 VARIATION AND INTERGRADING OF FOUR SPECIES OF BULIMELLA ur 1 4 j ‘ b € eae Aye MeO ¥ EXPLANATION OF PLATE B. 43 LETTERS USED ON PLATE B, TO DESIGNATE THE VALLEYS AND DISTRICTS ON THE ISLAND OF OAHU. a, Waialei b, Pupukea. c, Waimea. d, Kawailoa. e, Opaiula. f, Helemano. g, Wahiawa. h, Ahonui. i, Kalaikoa. j, Waipio. k, Waiawa. 1, Ew { Waimano. Waimalu. m, Halawa. n, Moanalua. o, Kalihi. p, Nuuanu. q, Pauoa. r, Makiki. s, Manoa. t, Palolo. u, Waialae. v, Wailupe. w, Niu. x. Keawaawa. M, Mokuleia. L, Lebut- W, Waianae. a, Kahuku. b, Malaikahana. c, Laie. d, Hauula. e, Kaliuwaa. j, Waiolu. g, Punaluu. h, Kahana. t, Keawa. 7, Hakepuu. k, Waikane. 1, Waiahole. m, Kaalaea. n, Kahaluu. 0, ( Ioleka. p, Kaneohe. Git,is; Kailua Gia { Ahuimanu. { Pohakunui. Olomana Peak t, u, v, w, Waimanalo. [Italic letters in the second column are to be regarded as the equivalent of the underscored jetters on the map.] Hi ee i ee vm ae in i ih wi Y i rea) A Nhs My uh j m y i) i i ts yaa / bill) Wie aa * at CHAPTER V. THE FOUR SEGREGATIVE PRINCIPLES. J. THE NEED oF A NOMENCLATURE DISTINGUISHING BETWEEN RACIAL AND HABITUDINAL SEGREGATION. 1. The Interaction of Acquired and Inherited Characters. The interaction of the factors producing racial segregation and those producing social or habitudinal segregation should, I think, be clearly recognized, and a suitable nomenclature used for presenting the same. Increasing attention is being given to this interplay of influences; but clear expression of the relations of the factors is con- stantly obscured by lack of terms for designating the processes of segregation relating to acquired characters or habitudes. In my paper on ‘‘Intensive Segregation”’ I emphasize the impor- tance of the forms of reflexive selection ‘‘due to the relations of the members of the same species to each other, and liable to change with- cut any change in the environment,” and of active (or endonomic) selection ‘‘due to change in the successful use of the powers of the organism in dealing with the environment.” In another paragraph I say: “‘ Diversity in the uses to which different sections of one species put their powers when appropriating resources from the same envi- ronment must produce diversity in the forms of variation that are most successful in the different sections. This I call active selection as contrasted with passive selection, which varies according to differ- ences in the environment. All diversities of environal selection that do not vary according to differences in the environment must be classed as diversities of active selection, for they must have originated in some variation in the powers of the organism, or in the diversity of uses to which it has putits powers.’’* The power of the organism to determine industrial segregation is considered in my paper on “‘ Diver- gent Evolution,” read before the Linnean Society in 1887. In 1896, Professors Baldwin, Osborn, and Lloyd Morgan were inde- pendently led to consider the influence of individual powers of accom- modation in enabling representatives of a species to survive in an environment that would otherwise be fatal, and so ‘‘giving time to the species to develop coincident variations (7. e., congenital varia- * See Appendix II, Section I, 8, (4) and (18). 45 46 THE FOUR SEGREGATIVE PRINCIPLES. tions in the same direction),’’** which are gradually accumulated by selection. Another point presented by the same writers is the conti- nuity of tradition, secured by training, suggestion, and example on the part of the parents and imitation on the part of the young. The effects of tradition have also been very clearly illustrated by F. W. Headley in his recent book.f I quote a few sentences in which he summarizes the effects of accommodation and tradition: The result is that among the higher plastic classes of animals evolution proceeds more rapidly. But obviously the quickening up of evolution is not all. The individual gains in importance. He improves his powers, is able to face a change of environment that otherwise would have been fatal. He makes an environment for his young in which intelligence can be developed; he chooses the environment which they shall have when out of the nursery, and so decides to some extent what qualities shall be the winning qualities in life. In fact, he is beginning to take the helm and steer the species. Or we may put it in this way: When the individuals of one generation decide the environment in which the next shall grow up, selec- tion ceases to be purely natural; it is in part artificial.t These quotations are sufficient to show that there is increasing recognition of the fact that there may be changes in the organism that are not dependent on changes in the environment, and are there- fore not dependent on change in the form of the natural selection. In choosing terms for designating these processes I think we should care- fully follow Professor Baldwin’s suggestion ‘‘that selection in the Darwinian sense should be used only when the essential conditions of organic progress by survival are present, namely, variations and physical heredity.’’s In my own usage, selection has been applied only to processes secur- ing the survival of part of the variations of a race or species with the exclusion of other variations, and so influencing its powers of heredity ; and isolation has been limited to the prevention of free crossing be- tween co-existing groups. In order to do this, and at the same time clearly present the principles controlling the evolution of habitudes, it has been necessary to find two terms that might hold the same rela- tion to innovation and tradition that selection and isolation hold to variation and heredity. The best words I have found are election * See letter from J. Mark Baldwin in Nature for April 15, 1897; also the same in Science for April 23, 1897, on ‘’Organic Selection.’”’ In this letter will be found references to discussion on the subject during the previous year in various books and journals. + Problems of Evolution, pp. 120-128. London, Buckworth & Co., 1900, and New York, Crowell & Co., 1901. t Problems of Evolution, p. 128. § See Science May 8,1898. The same limitation is also advocated in his Social and Ethical Interpretations, Appendix B. SEGREGATION A FUNDAMENTAL LAW IN THE ORGANIC WORLD. 47 and partition. The need of such terms will, I am sure, be recognized by many, though some may not consider the words I have chosen the best. 2. Segregation is a Fundamental Law in the Organic W orld. One sphere in which it operates is racial (or aptitudinal) segrega- tion, produced by the intergeneration of individuals with like innate characters. Another sphere is social (or habitudinal) segregation, produced by the association with each other of individuals with like acquired characters. Segregate generation (1. e., the generation of like with like), 7s a condition on which the present structure of the organic world depends. Without segregate generation the differences of races, species, genera, and the higher groups could never have arisen, and if it were possible that it should cease, all these distinctions would ere long be obliterated. The fact that race characters are hereditary renders it certain that freely intergenerating races will, in a few generations, become one race. But the fundamental nature of the organic world is such that the only cases in which the law of segre- gation can be broken down are those in which the divergence is com- paratively small. When amalgamation takes place it is usually varieties of the same species that unite. When physiological incom- patibility has once been fully established, the segregation is never broken down; but, on the other hand, as long as there is any plasticity in a race, it is possible that new segregations may be introduced and one race divided into two or more races. Having observed that segregate generation is the fundamental principle by which the world of sexually reproducing organisms is maintained, and having discovered that the art of breeding, by which the multitude of domestic races has been produced, rests on the control of segregate breeding, we propose to make careful investiga- tion of the different forms of control influencing this principle and of the effects thus produced. As an equivalent for segregate generation (or the breeding of like individuals with like), Romanes has proposed the term ‘‘homogamy.”’ An objection to its use in this meaning is, however, found in the fact that in botanical language the same term has a somewhat different meaning. It should be noted that this statement concerning the breeding of like with like does not imply that creatures freely mating with each other are entirely free from differences. Of multicellular organisms no two were ever found to be exactly alike; if, therefore, there is any mating of these creatures, it must be the mating of creatures that are not completely the same, either in structure or function. The 48 THE FOUR SEGREGATIVE PRINCIPLES. point is that the greatest difference existing between any form of organisms and any other form that is capable of crossing with it, is very small compared with the differences presented by the vast world of organisms that are incapable of crossing with it. Cross- fertilization secures the blending of elements from individuals that are more or less divergent; but the degree of divergence that may exist without resulting in sexual incompatibility, either physiological, morphological, or psychological, is very small compared with the divergences that lie beyond the limits of compatibility. Again, we find that in some cases species incapable of crossing are so similar in visible characters that the naturalist finds difficulty in distinguishing them. 3. Segregate Assoctation,* a Fundamental Law on which the Social Structure of Each Species that is not wholly guided by Instinctive Aptitudes must rest. The necessity of a common language for a social group will be rec- ognized by all. There must be a system of signs or signals by which the members of one group may call to each other when they wish to come together, may warn each other of approaching danger, and may in other ways codperate in securing the sustenance, protection, and propagation of the group. If these signs are not instinctively made and instinctively understood, they must depend on suggestion, train- ing, and imitation; and this suggestion, training, and imitation is made possible by the association maintained by the social group. It is a universal fact that the social characteristics of individuals of the same associating group are gradually unified by association. Again, it is certain that a group of freely associating and freely intergenerat- ing individuals of different races of mankind will in time become assimi- lated in language, manners, and customs, and finally in race, however different they may have been when first brought together. The blending of two strongly marked species is usually prevented either by instinctive aversion, by unfruitful crossing, or by the sterility of the hybrid offspring, as in the case of the mule; while the blending of two civilizations is liable to be prevented by the superior power of one completely overshadowing the influence of the other. Moreover as long as racial barriers are not broken down, distinctions of social types are not often wholly obliterated. This is naturally the case as long as the training of the young, and so the transmission of tradition, remains chiefly with the parents. Segregate association, that is, the association of like with like, is the fundamental factor in the production of habitudinal segregations; * That is, the association with each other of individuals with like acquired char- acters. THE INTERACTION OF RACIAL AND SOCIAL EVOLUTION. 49 and, as will be more fully explained in another chapter, it is brought about by the codperation of habitudinal demarcation through parti- tion, and habitudinal intensification through election. The methods of this election are first through the different forms of approval and disap- proval used in training the young, and second through the promotion and wide influence given to individuals attaining the highest recog- nition of public opinion and the suppression of individuals falling below the lower limits set by the laws and customs of the community. Divergent forms of civilization can neither be established nor main- tained without the continuous operation of segregate association. For designating the effects of segregate association I often use the term “‘habitudinal segregation”’ rather than ‘‘social segregation,”’ because in creatures entirely guided by instinct there may be elab- orate forms of social organization, and therefore forms of social segre- gation, that rest mainly, if not entirelv, on racial characters produced by racial segregation; while under “ habitudinal segregation’’ I wish to consider the evolution of acquired characters under the operation of segregate association. If ants and bees learn by training and imita- tion incorporated in traditions, then the growth of their social organ- izations should be treated under this department of segregation; but, if not, then their evolution, both physical and social, comes under the department of racial segregation. 4. The Interaction of Racial and Social Evolution must be considered. The interaction of racial and social (or habitudinal) evolution and the exposition of the laws regulating the same, by which man is to gain control of his own evolution, is the broad sphere in which the biology and sociology of the future will expand. Ward, Giddings, Baldwin, and other Americans are exploring this field, and in Europe the trend is in the same direction, if I judge rightly. The nomen- clature which I propose and illustrate in the following pages will, I think, aid in discussing the problems of biology and sociology that are now coming to the front. I should not have had the patience and courage to attempt to present a scheme for so wide a field if I had not seen the pressing need for such a method from the side of biology. I also believe it will be a great advantage for sociology if a harmonious and correlated nomenclature can be brought into use in both biology and sociology. Some sociologists, recalling the nomenclature and exposition introduced by Herbert Spencer on the basis of an assumed correspondence between the biological and the social organism, will instinctively shun the use of a terminology that suggests a correspon- dence and interdependence between the two spheres of evolution. There will, however, be others, who have come into sufficiently close 50 THE FOUR SEGREGATIVE PRINCIPLES. contact with the problems of evolution, in both realms, to realize that great illumination for each will be found in the study of the interac- tion between the two realms. Those who are doubtful concerning the interaction of the two spheres will gain light from Baldwin’s Social and Ethical Interpretations and his Development and Evolu- tion, and from the discussions on organic selection given by Osborn, Baldwin, and others in Science and The American Naturalist during 1896-98. Me m M—Mc M—Mc—m '~M—Mc Fs Ege UE hh = Formula (3) ;* PSM e—=m and rate mc ae : C=Px RES Eee ha Formula (4) ; TABLE A. {From Formula (4).] When M = 10 | andm= 9. 8. Te 6. Si, 4. Bice ih 1 ici i then aaa 9 8 i 168 a 4 3 | 2 1 = pure-breeds X we mio mie Ae Q 2 4 6 8 | If c = }, then C = P x a 4, 5 : 2 i 3 2 x sh Aa TE Se eae 7 : i a sued s | = aes 1 A ae ae = a sat = #5 590 an | a | se | | ae ae pias Grin a ans = aS as | aS | = | ce | ae * Formulas (1) and (2) were given in my paper on Divergent Evolution (see Appendix I). 106 ANALYSIS OF THE FOUR PRINCIPLES. Method of Testing Table A. Let M=10; m=7; c= a then © —2 according to the table. We now place under pure-breeds any number, and under cross- breeds 34 times that number. Pure-breeds. Cross-breeds. = In nth generation, 2 | In nth generation, 7 = Gr. xt = 2(M — Mc)'= 15 | In(n+ 1)th gen., 49+ 2 Z (n+ 2)th ‘ | 2N(Fa5) i. a Mien (15s on] 2 (one {= ar24 Nonagenss aay ies pari A = 2(M — Mc)? \ ] = 2(56.4) = 343-+ 244 + 26} \ Starting with the fraction 7 given in Table A, as correct for the 2’ nth generation, we find that 5= Z is correct for all subsequent gene- rations; and this proves the formula to be correct. If the denominator of the fraction representing the value of ois o, or less than o, the disproportion increases with each generation ; that is, cross-breeds become the overwhelming element. In this case by which we are testing the correctness of Table A, suppose the pure-breeds to be 2 and the cross-breeds to be 7 in the generation with which we commence. In the next generation, which we designate as the (n+ 1)th generation, the pure-breeds will be 2x (M —Mc)!=2 co 10 | l 4 J the pure-breeds = 2 X (M — Mc)? = 2 X (7.5)? = 112.5. The cross-breeds in the (7+ 1)th generation = 7 X< the cross- breeds of the previous generation, plus 7 < one-quarter of the pure- In the (n + 2)th gen- — 15. In the (n+ 2)th generation 5 breeds of the previous generation = 7? + lb | eration the cross-breeds will be 7 x the cross-breeds of the (m * 1)th generation, plus 7 * one-quarter of the pure-breeds of the (m + 1)th (15 4 ‘ : generation = 73 + r+ x 7| = 303-75- \ USE OF THE TABLES. 107 16. The Use of the Tables. The first object of this computation is to show that a partial posi- tive segregation that is ineffectual in preserving a new variety from the swamping effects of crossing becomes very effectual when a mod- erate degree of segregate fecundity codperates with it. It should be observed that when considering partial segregation codperating with segregate fecundity I assume that the two varieties that are compet- ing on the same area are equally adapted to the environment, and that the action of other principles is equal in each, in order that I may compute the effects of the two factors under consideration when free from disturbing influences. It has been objected that, according to my Table I,* the eighteenth generation is many thousand times larger than the initial number, which is not the usual result under the condi- tions surrounding natural varieties. In reply I would say that even in natural varieties it is not at all impossible that the number should double with each generation for at least a few generations, especially when a variety has gained the use of resources heretofore unused, and that for the purpose of showing the ratio in which half-breeds and pure-breeds stand to each other it is entirely immaterial whether we assume that the number that arrive at maturity are the same in each generation, or that each successive generation is nearly double that of the preceding generation. But does not the assumption that the ratio of cross-breeding re- mains the same in successive generations vitiate the whole computa- tion and render it worthless? I think not. My contention is that when segregate fecundity comes to the aid of such a principle as pre- potential segregation (which is only partial in its action, and therefore by itself unable to prevent swamping), the result is the progressive action of both principles in each successive generation. But before we can show how this cumulative action arises we must have some formula for showing the natural result of any given degree of segre- gation combined with a given degree of segregate fecundity; and the proper formula for this purpose seems to be the result that would be reached, if the principles should continue at the given degrees for a considerable number of generations. Take for example the case represented in Table I.* What is the ratio between half-breeds and pure-breeds that most truly represents the case? Shall we go to the end of the first generation and say that, — or go to the eighteenth generation and find that == * See my paper on Divergent Evolution, Appendix I. 108 ANALYSIS OF THE FOUR PRINCIPLES. Undoubtedly the latter is the one we need to represent the result toward which the given conditions tend, though before the eighteenth generation is reached the degree of segregate breeding will have become more stringent. Having obtained a formula giving the results that would be reached if the ratios of cross-breeding and of attendant infertility were con- tinued at a given level for a number of generations, we next inquire whether there is any reason to believe that the degrees of segregate breeding will become more stringent in successive generations, and whether the infertility of cross-breeds will be increased. 17. Cumulative Segregation Resulting from Segregative Endowments. Let us consider a partially segregated variety of a plant species in which there is some variation in the segregative endowments. We will suppose that the species is one whose pollen is freely distributed by the wind and whose stigma is susceptible of fertilization for ten hours. Though the individuals of the new and partially segregated variety are very few as compared with the original stock, yet the pollen of the new kind reaches every stigma of the same kind before the ten hours of its susceptibility have passed, while pollen of the original kind, be- ing far more abundant, is sure to reach every stigma soon after their flowers have opened. The positive segregation of the new variety we will suppose is se- cured by prepotence of the pollen of the variety on the stigmas of the same variety, one variation being prepotent for about five hours, with the result that one-half of the individuals breed pure and one-half are crossed; that is, c=4; while another variation is prepotent for about 62 hours, with the result that two-thirds of the individuals breed pure and one-third are crossed; that is c = 4. The negative segregation of the new variety we will suppose is se- cured by segregate survival; for the pure-breeds, through different degrees of adaptation to the new station, enjoy different degrees of success in leaving offspring that come to maturity, the less adapted variations being multiplied by 1 in each generation, and the better adapted multiplied by 2 in each generation, while the cross-breeds are so lacking in adaptation as to be multiplied by 3 in each genera- tion. We therefore have two values for M, each occurring under c=4, and again under c= 4. In one variation we have M=1, and 1, the proportion being as M = 10, and m2; and in the other vo TS variation we have M = 2, and m=, the proportion being as M = to and m = 1. CUMULATIVE SEGREGATION THE RESULT. 109 Solution reached by means of Table V.—Looking in Table V,* we find that when c = 4, and M ~1o, (var. 1) then with m = 2, half-breeds = pure-breeds = 2; (var. 2) and with m = 1, half-breeds = pure-breeds = a that when c = }, and M = io, (var. 3) then with m = 2, half-breeds = pure-breeds < 25 (var. 4) and with m = 1, half-breeds = pure-breeds x a Now, it is evident that the influence on the next generation of the variation marked as var. 4, which is the most highly segregated, will be much greater than that of any other one of the variations. Solution reached by means of Table A.—If we consult Table A, we shall find an equal contrast, for it gives for (var. 1) cross-breeds = pure-breeds x 2; (var. 2) cross-breeds = pure-breeds x ae Be (4? (var. 4) cross-breeds = pure-breeds = +. Solution reached by direct computation —A similar conclusion may be reached by computing the result for a few generations. Let us suppose that for one-half of the new variety the average prepotence allows one-half of the individuals to form cross-unions, and that for the other half of the variety the average prepotence allows only one- third of the individuals to form cross-unions; and also that one-half of _ each of these variations is so adapted as to multiply by 2 in each generation, while the other half multiplies by 1. As in the previous computation cross-breeds are multiplied by 4 in each generation. Let us now assume that in a given generation there are 1,000 indi- viduals in each of these variations, and what will be the number of pure-breeds of each of the four variations that will come to maturity in the next generation, and what the number of cross-breeds? haart, 6 =, M1, m ==, G. ¢.,-piire-breeding ‘Seo, crossing 500), .”. pure-breeds 500; half-breeds roo. nae 26 — 4, M2, m=; (1. ¢.,.pure-breeding, 5005 crossing Ab) (var. 3) cross-breeds = pure-breeds X 500), .°. pure-breeds 1,000; half-breeds too. Petes i M1, 1 1; (. e., pure-breeding 666; crossing 333), .'. pure-breeds 666; half-breeds 66. In var. 4, c— 1, M=2, m= ¢; (. e., pute-breeding 666; crossing 333), -'. pure-breeds 1,332; half-breeds 66, The sum of the pure-breeds of all the variations 3,498. It will be observed that in one generation the pure-breeds have decreased from 4,000 to 3,498; that is, their numbers have dimin- * See my paper on Divergent Evolution, Appendix I. 110 ANALYSIS OF THE FOUR PRINCIPLES. ished one-eighth. In the second generation the result will be quite different; for variations 2 and 4 already constitute two-thirds of the whole number of pure-breeds. Second Generation— Pure-breeds. Of variation: . : ; : , : 5 : 250 Of variation 2 . ; : : F : : : 1, 000 Of variation 3 . ‘ ; : 5 : 3 , 444 Of variation 4 . ; : : 3 : : ; 1,776 3,470 In this generation the decrease is only 28 individuals, or about >. Third Generation— Pure-breeds. Of variation: . , , : : : : ; 125 Of variation 2 . , : : : : F : I, 000 Of variation3 . i ; : : : ‘ : 296 Of variation 4 . ; ; i f t , ; 2, 368 3, 789 In this generation there is an increase of 319 individuals, or a little over 4. Fourth Generatiton— Pure-breeds. Of variation: . , : : ; A ; : 62 Of variation 2 . : , : P : : p 1, 000 Of variation 3 . ; i . 4 ; : ‘ 198 Of variation 4 . 4 : . F : : A 3a n56 4,416 In this generation there is an increase of 627, or of nearly +. Tenth Generation— Pure-breeds. In variation 1 . : : : ; s 5 : 0.98 In variation 2 . ; ‘ ; : ‘ : , 1, 000 In variation 3. ; ; 4 ; : ; : 16 In variation 4. . . : . 5 : Sein iGys 18,775 Var. 4, of Tenth Generation = 1,000 (1.33334)'° computed by logarithms. We therefore observe that in the tenth generation variation 1 has become less than 1, and variation 4 has become the predominant type. For the next ten generations the average positive segregation will be advanced, (1) by the preponderance of variation 4, and (2) by the fact that the new variety occurs in much larger masses than at the beginning of the computation, and will therefore be less exposed to cross-fertilization. Now that the mass of pure-breeds is increased more than fourfold, it is reasonable to suppose that the ratio of pure-breeding advances. INSTITUTIONAL AND PRUDENTIAL SELECTION. Til We may also assume that increased segregate fecundity and vigor will make the multiplier for pure-breeds = 2, and the multiplier for . cross-breeds = j. And when another ten generations have passed, still higher degrees of segregation will be the natural result. Conclusion.—We have now approached in three different ways the proof of cumulative advance in a set of innate qualities, which by their combined action produce in moderate degress both positive and negative segregation. The result seems to be that when by any chance comes to be larger than Mc + m, then the fraction mc M—Mc—m becomes a positive quantity, and a given proportion of the whole stock remains unaffected by crossing. This point having been reached the subsequent tendency is toward a constant increase in the segre- gative endowments. , which gives the ratio of cross-breeds to pure-breeds,* 18. Institutional and Prudential Selection. Institutional and prudential selection stand in the same relation to the other forms of reflexive selection that artificial selection holds in relation to natural selection. They are the forms of reflexive selec- tion established in communities of rational beings for the purpose of securing ends that are more or less fullv apprehended as the goal. It should be observed that inherited instincts have an important part in each of the forms of conjunctional selection, that is, in sexual, social, and filto-parental selection; and again in the forms of impreg- national selection and impregnational isolation just discussed, the coordinations are due to inherited characters, either morphological or physiological; but in institutional and prudential selection the processes are guided by conscious and reflective purpose. It will, therefore, be seen that the conscious regulation of relations between husband and wife, between man and man, or between parents and children, when it affects the form of survival, belongs to either insti- tutional or prudential selection, and not to conjunctional selection in any one of its three forms. In the past history of man the three forms of conjunctional selection have been of prime importance; but as civilization advances increasing control is given to institutional and prudential selection. Moreover, in the case of civilized man, domina- tional selection through intra-group struggle has in a large measure ceased to be a struggle for life or for the opportunity to have a full share in producing the next generation, and has become chiefly a struggle for influence in society and for escape from certain forms of * See Formula (4), on page 105. 112 ANALYSIS OF THE FOUR PRINCIPLES. drudgery. If degeneracy is threatened, the remedy will not be found in restoring the conditions of savage life, in which the imbecile and the insane, the deaf and the diseased, are all eliminated by starvation ; but rather by such forms of institutional and prudential selection, enforced by public opinion and law, as will prevent the marriage of those who are specially liable to have defective offspring. It thus appears that institutional selection and prudential selection, both of which may be subjected to rational control, are the chief factors by which man may hope to maintain and control his own evolution. The powerful influence of institutions on human evolution will be recognized by those who consider the effects that must be produced on the vigor and vitality of a nation when military organization and destructive wars prevent many of the most vigorous men from having anv share in producing the next generation, while many others who leave children are suddenly removed by death when their families most need their aid. Again, the institutions in which the community combines for the maintenance of justice and order and the training of the young must have a profound influence on the physical inheritance of the race, through the advantage it gives to the peaceful and law- abiding. In the evolution of civilized man the law of natural increase is liable to be set aside in a way that often becomes extremely abnormal. I refer to the effects of prudential selection in limiting the size of families, both by delaying marriage and by restraint after marriage. Of course, both methods of using the reason are legitimate if the end sought is not a selfish desire to be free from care and responsibility. The evil has grown to such proportions in certain communities that the very existence of these groups is threatened. The fundamental difficulty seems to be that public opinion has failed to set before the men and women of force and character—before those who are the back- bone of the nation—the double ideal of maintaining a vigorous life and civilization during their own generation and of transmitting the same to a posterity of unabated vigor and of high native character, as well as of high training and culture. It is impossible that this standard should be attained if there is unwillingness to establish family relations until the battle of life has been fought out and won. Nor can it be realized if after marriage those who should become parents wish to reserve the chief portion of their energy for social entertainments or for the pleasures of art, science, literature, and travel, with no consideration of how these great gifts of past genera- tions can be best transmitted and rendered continuously progressive INSTITUTIONAL AND PRUDENTIAL SELECTION. 113 in the hands of those who are capable of receiving, maintaining, and transmitting the same.* This factor is probably having a profound influence on the present ‘ evolution of the most highly civilized nations. In his volume on The Chances of Death, Karl Pearson says in a note (see p. 83): Mr. Francis Galton tells me that he was recently informed by credible medical authorities in Paris that the French population is becoming Breton, owing to the fact that this element of the population does not limit its fertility to anything like the same extent as other elements. Nearly all large families are found to be of Breton extraction. Similar changes of population are taking place in New England and in other countries, and in some of these cases the cause is probably the one we are now considering. The continuance cf any human race depends not only on its power to produce vigorous and adapted off- spring in sufficient numbers, but on its willingness to exercise this power and to assume the heavy responsibilities of rearing and train- ing the young. If the Bretons are willing, and persist in being willing, France may become their inheritance: if they give way, the inheri- tance will pass to others. But the French are not the only people that are threatened by this selfish individualistic civilization. Its blighting effects are apparent among the professional and commercial classes in other countries. The statistics obtained by Karl Pearson, some relating to families of Anglo-Saxon extraction and others relat- ing to Danish families, do not give the proportion of the same classes that remain unmarried; but careful analysis of the facts given leads him to remark: There are clear traces in the statistics of some special action influencing fertility in families with between 3 and 7 children. * * * It is noteworthy also that this characteristic is less marked in statistics drawn from pedigrees than in more recent natal statistics. I can not, therefore, avoid the conclusion that the dip between 3 and 7 is not due to compoundness; that its origin is comparatively recent, and that it is an artificial break in the natural smoothness of the curve of fertility. I believe it to be entirely due to a Malthusian restraint on population. Families which reach 7 and over appear to be those in which no check is placed on the ‘‘natural’’ growth. Below 7 there is a tendency to restraint which is * Since this paragraph was written Mr. Francis Galton has delivered the second Huxley lecture of the Anthropological Institute (of London), in which many suggestions are made for reversing the present unfavorable action of prudential selection. The lecture is entitled ‘‘The Possible Improvement of the Human Breed under the Existing Conditions of Law and Sentiment,” and is published in ‘‘Nature”’ Oct. 31,1901. In his view the high racial development of the most gifted fiftieth part of the human race is of more importance than the suppression of the lowest type, though he recognizes both methods as needed for reaching the best results. 114 ANALYSIS OF THE FOUR PRINCIPLES. marked by a transference of frequency from families which should lie between 4 and 7 to those lying between o and 4. * * * While the theoretical curve will be found to give only 6 to 8 per cent of marriages without issue, we find in modern statistics 11 to 18 per cent of marriages with no issue * * * and thiseven in countries like England and Denmark, where restraint is not usually supposed to be so prevalent as in France.* Again, he remarks: ‘‘The prudential restraint on marriage and parentage in the more educated members of the community, which we are apt to regard as a social virtue, may after all have its dark side,’ 7 19. Institutional Election, Partition, and Isolation. Institutional election arises through the influence of public opinion giving prominence, influence, and success to individuals who conform most fully to the social standards of justice and propriety; and is rein- forced by the law which puts a definite check on individuals whose actions fall so far below these standards that the community will not tolerate the offenders. Again, each community has its language, its industrial methods, its arts and sciences, and its forms of etiquette, which must be transmitted by tradition from generation to generation, for these attainments can not be transmitted by racial heredity, and their continuance in the community depends on example, education, and training on the part of the older generation, and on the part of the younger generation imitation, study, and practice. Now, insti- tutional election includes the superior success and influence of the individuals who attain the most complete equipment in these acquired characters that belong to the community. Institutional partition arises when local isolation and partition has resulted in divergence in language, religion, and education, preventing the possibility of association in one community when local isolation and partition has ceased. Institutional isolation.—Again, the differences in language, religion, and education, which prevent free association, will also prevent free intermingling of race, and the result is institutional isolation. Exam- ples of institutional partition and isolation are seen in the Mohamme- dan and Christian communities occupying the same regions in Turkey. * See Chances of Death and Other Studies in Evolution, pp. 67—69. flbid., p. 102. CHAPTER VII. ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). I. THE METHODS OF THE ENVIRONAL MODE OF EACH PRINCIPLE, WITH THE ForMS OF EACH METHOD. Producing demarcation of habitudinal Producing intensification of habitudinal groups: groups: Environal partition. Environal election. Endonomic partition. Endonomic election. Industrial partition. Habitudinal election. Migrational partition. Aptitudinal election. Heteronomic partition. Heteronomic election. Transportational partition. Natural election. Geological partition. Artificial election. Artificial partition. Producing demarcation of racial Producing intensification of racial groups: groups: Environal isolation. Environal selection. Endonomic isolation. Endonomic selection. Industrial isolation. Habitudinal selection. Chronal isolation. Aptitudinal selection. Seasonal isolation. Heteronomic selection. Cyclical isolation. Natural selection. Migrational isolation. Artificial selection. Heteronomic isolation. Transportational isolation. Geological isolation. Fertilizational isclation. Artificial isolation. Having completed our analysis of the methods and forms of the reflexive mode of influence, we will now briefly survey the forms of the environal mode. Under each or the four principles, when we find that the relations between the group and its environment are determined by conditions within the group, we call the influence endonomic selec- tion, election, isolation, or partition, as the case may be; or if the relations are determined chiefly by conditions lying outside of the group, we then speak of the influence as heteronomic. 1. Environal Selection and Environal Election. Environal selection, as we have just seen, may be either endonomic or heteronomic. Divergent forms of endonomic selection often arise through divergent habitudes or aptitudes of the individuals starting the isolated colonies, or through the accidents attending the entrance of small groups into isolated 115 116 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). districts presenting the same environment.—In my paper reproduced in Appendix II of this volume I have emphasized the fact that it is true of a very wide range of species that any one species distributed in small sections in several isolated districts, presenting the same envi- ronment, will often use the environment in different ways, and so be subjected to different forms of selection. Selection thus determined by the relations in which the organism puts itself to the environment I call endonomic selection. We shall here consider in fuller detail the different conditions that may produce divergent forms of selection in isolated groups, exposed to the sameenvironment. Let us first consider cases in which the isolated groups are very small, and from a species with many variations through adaptations to a complex environment, and in which the new dis- tricts to which they are brought present the same environment as is found in the original home of the species. That the conditions may be clearly apprehended, let us suppose that we are considering a species of Hawaiian tree-snails on the southwest side of the main mountain range of Oahu, confined to the shady groves of a single val- ley, shut in on either side and at the head of the valley by high ridges covered with open brush, and at the mouth of the valley by grassy slopes that extend to the sea. This snail lives continuously on the trees, clinging to the trunks and large limbs of five or six species, and presents many variations of color and some divergences in acquired habitudes according to the species of tree on which it has lived. If for many generations a certain strain should live entirely on one species of trees (perhaps occupying a single grove which includes no other trees), it would present innate aptitudes for that kind of life, devel- oped by selection. Now, suppose that by some very rare accident a man, bearing a branch of a tree, unconsciously transports a single impregnated individual of this species of snail into the neighboring valley on one side, and within a few years a similar occurrence carries another individual of the same species, but occupying another kind of tree, into the valley on the other side. Each individual has occu- pied but one kind of tree for its whole life, and having formed habi- tudes strongly favoring the kind it has so far used, seeks and finds the same kind in the new district to which it has been brought. As there is no pressure of population in their new and previously unoccupied districts, the descendants of each remain for a hundred years or more in the grove in which the first comer settled down; and the two colo- nies have, perhaps for a hundred generations, been subjected to some- what divergent forms of selection; for the habits of feeding have been different, and there has been no crossing between those of different ENDONOMIC AND HETERONOMIC SELECTION. shy) habits, as was the case in the original home. ‘This is an illustration of what I call ‘‘habitudinal selection.’’ We shall next consider an illustration of aptitudinal selection, which will be gained by changing the illustration just given at one point. Instead of taking the two individuals which start the two colonies from those which for a genera- tion have been feeding on different kinds of trees, we must take them from two separate strains which have, for many generations, had their separate methods of feeding, so that not only their habitudes but their aptitudes must be somewhat different. Again, we may consider conditions that would produce what we might call ‘‘acct- dental selcction.” ‘This might occur if the two individuals starting the two colonies were from, the same strain and had both of them gained various experiences by feeding on different trees, so that their habits were not fixed. One of them we will suppose was brought by accident to a fine grove of candle-nut trees in the new district, and for a hundred years finds no cause to go elsewhere; while the other one, in another valley, is brought to a grove of what the Hawaiians call ohia trees, and there remains for an equal number of years. Is it not certain that the selection will be somewhat divergent; and to what determining cause shall we attribute the divergence if not to accidents that started these individuals of varied attainments in separate colo- nies, and in groves of different kinds of trees? As the valleys are near together and on the same side of the mountain range, the rain- fall and other features of climate must be essentially the same. If the creatures under consideration were insects endowed with digher powers for exploring the environment, I-recognize that accidents of the kind here suggested would have little or no effect in determining the forms of selection; for, in such cases, slight differences of aptitudes or habitudes would be sure to control the method of using the environ- ment. Moreover, such species would not fall into isolated groups through their occupying separate valleys. When an isolated individ- ual or pair deals with an environment possessing resources that are varied but familiar and easily explored, previous habitudes and apti- tudes are the chief factors controlling the methods of using the environment. If the power of using different resources is great and the power of exploration small, the method of using the envi- ronment may be determined by the kind of resources first reached on entering the district. Heteronomac selection is of two forms—natural selection, produced by conditions in the environment that are independent of any purpose to control the forms of survival, and artificial selection, which is deter- mined by more or less distinct purpose to control survival. If in the 118 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). case of the snails just considered some of them are brought to groves on the northeast side of the mountain range, they will be exposed to a somewhat greater rainfall, and will probably be subjected to some change through the resulting selection. Again, suppose a colony is planted on either side of the range, in a valley where but one kind of shade trees is found, and this a kind that has never before been occu- pied by the species. In both these cases we should have heteronomic selection of the form that has been called natural selection. If any of these snails should be discovered by man to be good for food or medicine, and should be subjected to selection for the purpose of improving the qualities sought, the result would be heteronomic selection of the artificial form. Environal election corresponds with environal selection in the general influences by which it is shaped; but it differs in the results produced, for it relatesto the intensifying of habitudes and acquired characters within the associating group. The higher the grade of intelligence the more marked are the changes and divergences intro- duced by acquired habitudes and characters, and accordingly, in such cases, endonomic election becomes the leading factor by which some new adjustment to the environment is developed into an established method of sustaining life; and if the inherited endowments are not in complete accord with the new life, coincident selection carries the adjustment to higher degrees; for variations favoring the conditions imposed by the new tradition will have the advantage. Examples of endonomic election preceding and introducing coincident selection are seen in the tree-climbing rats mentioned above,* and in the cats that have taken to wading and fishing.t Heteronomic election is either natural or artificial. Avtzficral election is seen in dogs and other domestic animals that have been subjected to training. Natural election is seen in the case of the chimney swift, which, in a large meas- ure, having lost the hollow trees in which it used to build its nests, has been forced to find a substitute in the chimneys built by the intruders who cut down its trees. The new habit is undoubtedly being reinforced by instincts gradually established by coincident natural selection. 2. The Methods of Environal Isolation. Endonomic tsolation.—It is evident that, when varieties of the same species of plant occupying the same areas are prevented from crossing by flowering at different seasons, the process which I call seasonal isolation is rightly classed as a form of endonomic isolation. The * See page 101. + See pages 67-68. INDUSTRIAL ISOLATION. 119 same is true of the cyclical isolation between two broods of the period- ical cicada when occupying the same district.* As each brood lives nearly seventeen years burrowing in the ground, and then spends the ’ few last weeks of its allotted life above ground breeding in the trees, it never hasa chance to cross with the other brood, whose time for breed- ing comes on another year, and each seventeenth year thereafter.f Industrial isolation and migrational isolation, so far as they are deter- mined by diversity in the habits or instincts of the members of the species, must also be classed as forms of endonomic isolation. Heteronomic rsolation.—In the four remaining forms of environal isolation, namely, transportational, geological, fertilizational, and artificial isolation, heteronomic influences must prevail. 3. Industrial Isolation. Industrial isolation is isolation arising from the activities by which the organisin protects itself against adverse influences in the environ- ment, or by which it finds and appropriates special resources in the environment. The different forms of industrial isolation are sustentational, pro- tectional, and nidificational isolation. For the production of industrial isolation it is necessary that there should be, in the same environment, a diversity of fully and of approx- imately available resources more or less separated, and in the organ- ism some diversity of adaptation to these resources, accompanied by powers of search and of discrimination, by which it is able to find the resources for which it is best fitted and to adhere to the same when found. The relation in which these causes stand to each other and through which they produce segregation may be described as separation according to endowment produced by endeavor according to endow- ment. From the nature of the process it produces segregation; for those of like aptitudes are brought together. It is evident that if initial variation presents in any case a diversity of adaptations to surrounding resources that can not be followed without separating those differently endowed, we shall have, in the very nature of such variation, a cause of segregation and of divergent evolution. Some slight variation in the digestive powers of a few individuals makes it possible for them to live exclusively on some abun- * For a full statement see U.S. Department of Agriculture, Division of Ento- mology, Bulletin No. 8, and Bulletin No. 14, New Series, 1898. + For a comparatively full account of the different broods of this species, and the problems raised by the remarkable facts, see Appendix II, Sec. III, 3. 120 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). dant form of food, which the species has heretofore only occasionally tasted. In the pressure for food that arises in a crowded community these take up their permanent abode where the new form of food is most accessible, and thus separate themselves from the original form of the species. These similarly endowed individuals will, therefore, breed together, and the offspring will, according to the law of divergence through segregation, be still better adapted to the new form of food. When other forms of isolation arise, they may be entirely independent of change in the environment, the only change being in the forms or functions of the organism. This special form of segregation is as dependent on psychological causes which guide the organism in finding and in adhering to the situation for which it is best fitted as it is on the initial divergence of the more strictly physiological adaptations by which it is able to appropriate and assimilate the peculiar form of resource. In the case of freely moving animals the psychological guidance is an essential factor in the success of the individual, while in the case of plants and low types of animal life the suitable situation is reached by a wide distribution of a vast number of seeds, spores, or germs, and the same situation is maintained by a loss of migrational power as soon as the germs begin to develop. In these lower organisms it is evident that the success of the individual must depend on its physiological rather than on its psychological adaptations; and if variation results in a slight difference in the kinds that succeed in germinating and in prop- agating in contrasted situations, we have diversity in the forms of natural selection affecting the seed, and the separation is what I here- after describe as local isolation passing into local segregation. We therefore see that what I here call industrial isolation depends on psychological powers acting in aid of divergent physiological adapta- tions to the environment, or in aid of adaptations that are put to different uses. Observation shows that there are a multitude of cases in which endeavor according to endowment brings together those similarly endowed, and causes them to breed together; and when the species is thus divided into two or more groups somewhat differently endowed, there will certainly be an increased divergence in the offspring of the parents thus segregated; and so on in each successive generation, as long as the individuals find their places according to their endowments, and thus propagate with those similarly endowed, there will be accu- mulated divergence in the next generation. Indeed, it isevident that endeavor according to endowment may produce under one environ- ment what natural selection produces when aided by local separation INDUSTRIAL ISOLATION. I21 in different environments. As it produces the separate breeding of a divergent form without involving the destruction of contrasted forms, it is often the direct cause of divergent transformations; while natural selection which results in the separate breeding of the fitted through the failure of the unfitted can never be the cause of divergence unless there are concurrent causes that produce both divergent forms of natural selection and the separate breeding of the different kinds of variations thus selected. Again, endeavor, according to endowment, often secures separation according to endowment; and this gives an opportunity for the inher- itable effects of diversity of endeavor (if there are such effects), to be accumulated in successive generations. In the relation of endowment and endeavor we have a striking example of the peculiar interdependence of vital phenomena. Diver- sity of endowment is the cause of diversity of endeavor and of segre- gate breeding according to endowment, and segregate breeding accord- ing to endowment is the cause of increased diversity of endowment. It is very similar to the relation between power and exercise in the individual. Without power there can be no exercise, and without exercise there can be no continuance or growth of power. The effects of industrial isolation are specially liable to be enhanced by that form of intensive segregation which I have suggested should be called suetudinal intension. Simple and familiar as the principles of industrial isolation and sue- tudinal intension may seem, their consistent application to the theory of evolution will throw new light on a wide range of problems. This law of divergent evolution through industrial segregation rests on facts that are so fully acknowledged by all parties that it seems to be a superfluous work to gather evidence on the subject. It may, however, be profitable to consider briefly whether the cases are fre- quent in which different habits of feeding, of defence, or of nest- building become the cause of separate breeding by which the same habits are maintained in one line of descent without serious interrup- tion for many generations. It isimportant to remember (1) that the separate breeding will arise with equal certainty whether the diversity in the habits has been initiated by original diversity in the instincts and adaptations of the different variations, or by competitive disrup- tion, through the crowding of population inducing special efforts to find new resources, and leading to diversity of endeavor; and (2) that in either case the result is what is here called industrial segregation. In the first case, when the creatures are guided by some diversity of inherited instincts, the process is directly segregative, while in 122 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). the second case it is primarily separative, but inevitably passes into segregate breeding. Divergence through diversity of use, and the resulting diversity of acquired characters, whether inherited or not, will operate as surely in the one case as in the other. Sustentational csolation arises from the use of different methods of obtaining sustentation by members of the same species. There can be no doubt that of the innumerable cases where phyto- phagic varieties (as they are sometimes called) of insects exist, a con- siderable proportion would be found on investigation to be permanent varieties, producing offspring that are better adapted to the use of the special form of food consumed by the parents than are offspring of other varieties; and it is evident that if the peculiar habits of each variety had no tendency to produce segregative breeding this result would not be reached, for each variety would be promiscuously min- gled with every other, and, though the tendency to variation might be greatly increased, the regular production of any one variety of young would be prevented. Protectional isolation is isolation from the use of different methods of protection against adverse influences in the environment. When a new enemy enters the field occupied by any species, different methods of escape or defence are often open to the mem- bers of the one species; and the use of these different methods must sometimes result in segregating the members according to the methods adopted. Some may hide in thickets or holes, while others preserve themselves by flight. Supposing the species to be an edible butter- fly occupying the open fields and the new enemy to be an insectivorous bird also keeping to the open country, certain members might escape by taking to the woodlands, while others might remain in their old haunt, gaining through protectional selection more and more likeness to some inedible species. Nidificational isolatton.—Let us now consider the effects of diver- gent habits in regard to nest-building. It is well known to American ornithologists that the cliff swallow of the eastern portions of the United States has for the most part ceased to build nests in the cliffs that were the original haunts of the species, and has availed itself of the protection from the weather offered by the eaves of civilized houses; and that with this change in nest-building has come a change in some of its other habits. Now, there is reason to believe that if the number of houses had been limited to a hundredth part of those now existing, and if that limited number had been very slowly supplied, this gradual change in some of the elements of the environment would have resulted in divergent forms of adaptation to the environ- CHRONAL ISOLATION. 123 ment in two sections of the same species. One section would have retained the old habit of building in the cliffs, with all the old adapta- tions to the circumstances that depend on that habit, while another section of the species would have availed itself of the new opportuni- ties for shelter under the eaves of houses, and would have changed inherited adaptations to meet the new habits of nest-building and of feeding. It is also evident that the prevention of free interbreeding between the different sections caused by the diversity of habits would have been an essential factor in the divergence of character in the sections. It simply remains to consider whether the industrial habit that separates an individual from the mass of the species will necessarily leave it alone, without any chance of finding a consort that may join in producing a newintergenerant. ‘The answer is that there is no such necessity. Though it may sometimes happen that an individual may be separated from all companions by its industrial habit, it is usually found that those which at one time and in one place adopt the habit are usually sufficient to keep up the new strain if they succeed in securing the needed sustenance. 4. Chronal Isolation. Chronal isolation is isolation arising from the relations in which the organism stands to times and seasons. I distinguish two forms—cyclical and seasonal isolation. Cyclical rsolation is isolation arising from the fact that the life-cycles of the different sections of the species do not mature in the same years. A fine illustration of this form of isolation is found in the case of Cicada septendecim, whose habitat is the northern portion of the Mississippi Valley and of the Atlantic States, though many outlying broods are found in other regions. The typical form has a life-cycle of seventeen years, but there is a thirteen-year race (Cicada tredecim Riley) found chiefly in the Southern States, and therefore separated from the typical form, both locally and chronally. As the life- cycle of this race is thirteen instead of seventeen years, in a district where the habitats of the two races overlap, even if there were no physiological or psychological incompatibility to overcome, inter- breeding could occur between the two forms only once in 221 years, that is, once in 13 generations of the longer-lived race, and once in 17 generations of the shorter-lived race. The distribution of the two races in different districts seems to indicate that local isolation under different climatic conditions has had an important influence in their development. It is manifest, however, that if during a period of 124 ANALYSIS OF THE FOUR*PRINCIPLES (CONTINUED). local separation, or if during the period of 221 years of cyclical separa- tion after the thirteen-year race was first formed, this race should become modified in the season of its appearing, there would after that be no mingling of race, though brought together in the same districts. This would be seasonal isolation, which we consider in a following paragraph; but what is of special interest here as examples of com- plete cyclical isolation is the fact that in each of several limited dis- tricts there are found two broods of the same race whose appearance above ground is always separated by the same number of years.* In any species where the breeding of each successive generation is separated by an exact measure of time which is very rigidly regulated by the constitution of the species, cyclical isolation will follow, if, through some extraordinary combination of circumstances, members sufficient to propagate the species are either hastened or delayed in their development, and thus thrown out of synchronal compatibility with the rest of the species. If, after being retarded or hastened in development so that part of a cycle is lost or gained, the old constitu- tional time measure reasserts itself, the isolation is complete. In such cases, so far as the time of maturing is concerned, the differ- ence is segregative, while in every other respect it will be simply separative, except as separation passes into segregation. If the periodical cicada wasas variable in form and color as is the Achatinella (as well as other genera of Hawaiian snails), we should probably find each brood characterized by easily recognized divergences. Seasonal isolation is produced whenever the season for reproduction in any section of the species is such that it can not interbreed with other sections of the species. It needs no argument to show that if, ina plant species that regularly flowers in the spring, there arises a variety that regularly flowers in the autumn, it will be prevented from interbreeding with the typical form. The question of chief interest is, under what circumstances are varieties of this kind likely to arise? Is a casual sport of this kind likely to transmit to subsequent genera- tions a permanently changed constitution? If not, how is the new constitution acquired? One obvious answer is that it may arise * For the fullest statement yet made of the habitats and years of appearance of the 14 broods of the 17-year race and the 7 broods of the 13-year race, see Bulletin 14, New Series, of the Division of Entomology, U.S. Department of Agri- culture, 1898. As an example of the overlapping of the habitats of two broods of the same race, observe that, on pp. 48 and 49 of this Bulletin, three of the counties of Iowa and three of Missouri are given as part of the district where Brood XIII will appear in the year 1912, and also as part of the district where Brood XIV will appear in 1913, both broods being of the 17-year race. Broods XXI and XXII, of the 17-year race, are also reported as appearing a year apart in Wilkes County, North Carolina. CHRONAL, ISOLATION. 125 under some special influence of the environment upon members of the species that are geographically or locally isolated from the rest of the species. But may not variation in the flowering season of a fairly homogen- eous species tend to produce greater variation in that respect in the next generation, and so on, till the divergence in the constitutional adaptation to season is carried to the greatest extreme that is com- patible with the best adaptation to the environment? I believe that it not only may, but must have this effect; and that the result will be that the average form which flowers at the most favorable season will so vastly predominate over the extreme forms that the latter will be but stragglers in comparison. In regard to the one point of the season of readiness for propagation, this principle is segregative, but in other respects it is simply separa- tive, unless through the principle of correlated variation other charac- ters are directly connected with the constitution that determines the season. It will be observed that seasonal isolation is produced by a parallel and simultaneous change in the constitution of members in one place sufficient to’propagate the species; while cyclical segre- gation is produced by a simultaneous acceleration or retardation in the development of members in one place sufficient to propagate the species without disturbing the regular action of the constitution under ordinary circumstances. 5. Spatial Isolation. Spatial isolation is isolation arising from the relations in which the organism stands to space. I distinguish two forms, viz, geographical and local isolation. Geographical tsolation is isolation that arises from the distribution of the species in districts separated by geographical barriers that prevent free interbreeding. Decided differences of climate in neighboring districts may be classed as geographical barriers. Local isolation is isolation that arises when a species with simall powers of migration and small opportunities for transportation has been, in time, very widely distributed over an area that is not sub- divided by geographical barriers. The segregation in this case is due to the disproportion between the size of the area occupied and the powers of communication existing between the members of the species occupying the different parts of the area. Though it is often difficult to say whether a given case of isolation should be classed as geographical or local, still the distinction will be found useful, for the 126 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). results will differ according as the isolation is chiefly due to barriers or to wide diffusion of the species. In geographical isolation the result is usually the development of well-defined varieties or species on oppo- site sides of the barriers; but in local segregation it often happens that the forms found in any given locality are connected with those in surrounding localities by individuals presenting every shade of intermediate character, and in general terms it may be said that the forms most widely separated in space are most widely divergent in character. It is, of course, apparent that when the divergence has reached a certain point the differentiated forms may occupy the same districts without interbreeding, for they will be kept apart by some, if not all, of the different forms of autonomic isolation. Three different forms of spatial segregation may be distinguished according to the causes by which they are produced, viz: Migrational isolation, caused by powers of locomotion in the or- ganism. Trans portational tsolation, caused by activities in the environment that distribute the organism in different districts. Prominent among these are currents of atmosphere and of water, and the action of migratory species upon those that can simply cling. Geological isolation, caused by geological changes dividing the ter- ritory occupied by a species into two or more sections. For example, geological subsidence may divide the continuous area occupied by a species into several islands, separated by channels which the creatures in question can not pass. Migration differs from transportation simply in that the former is the direct result of activities in the organism, and the latter of activi- ties in the environment, and though the distribution of every species depends on the combined action of both classes of activities, it is usually easy to determine to which class the carrying power belongs. The qualities of the thistle-down enable it to float in the air, but it is the wind that carries it afar. Some degree of local isolation exists whenever the members of a species produced in a given area are more likely to interbreed with each other than with those produced in surrounding areas, or when- ever extraordinary dispersal plants a colony beyond the range of ordi- nary dispersal—in other words, when those produced in a given dis- trict are more nearly related with each other than with those produced in surrounding districts, there local isolation has existed. There is one important respect in which spatial isolation differs from all other forms of isolation, namely: In its ordinary operation it does SPATIAL ISOLATION. 127, not bring together those of similar endowments, and does not depend ondiversity. The dispersion of the members of a species would not be prevented if each was exactly like every other; though, of course, if there were no power of variation, separate breeding would have no influence in producing divergence of character. It follows that every species is more or less liable to be affected by spatial isolation; and it often happens that other forms of isolation arise through the previous operation of this form; but as spatial isolation prevents organisms from crossing only when separated in space, it must always be reinforced by other forms of isolation before well-defined species are produced that are capable of occupying the same district without interbreeding. Many slightly divergent forms arising through local isolation are reintegrated with the surrounding forms, new diverg- ences constantly coming in to take the place of the old; but if, during its period of local divergence, industrial or chronal isolation is intro- duced, the variety becomes more and more differentiated, and, as one after another the different forms of reflexive segregation arise, it passes into a well-defined species. As spatial isolation does not necessarily depend upon diversity in the qualities and powers of the organism, it usually fails of distributing the varieties of a species in different localities according to their differences of endowment. The causes that produce it are primarily separative, not segregative. Migration is produced by the natural powers of the organism acting under the guidance of instincts that usually lead a group of indi- viduals, capable of propagating the species, to migrate together; while organisms most dependent on activities in the environment for their distribution are usually distributed in the form of seeds or germs, any one of which is capable of developing into a complete community. The causes of isolation between the different sections and of inte- gration between the members of one section are, therefore, sufficiently clear; but what are the causes of differences of character in different sections, especially when they are exposed to the same environment? These causes all come under what I call typal intensification through diversity of success and diversity of survival. 128 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). 6. Ferttlzational Isolation. Francis Galton’s short article on ‘‘The Origin of Varieties,’ which was published in Nature, vol. xxxIv, p. 395, refers to this cause of isolation. He says: If insects visited promiscuously the flowers of a variety and those of the parent stock, then—supposing the organs of reproduction and the period of flowering to be alike in both, and that hybrids between them could be produced by artificial cross-fertilization—we should expect to find hybrids in abundance whenever members of the variety and those of the original stock occupied the same or closely contiguous districts. It is hard to account for our not doing so, except on the supposition that insects feel repugnance to visiting the plants interchangeably. It is evident that isolation of this form depends on divergence of character already clearly established, and, therefore, on some other form of isolation that has preceded. It is also segregative rather than separative, in that it perpetuates a segregation previously produced, which might otherwise be obliterated by the distribution of the differ- ent forms in the same district. The form of isolation that precedes fertilizational isolation, producing the conditions on which it depends, must, in the majority of cases, be local isolation. Chronal and impregnational isolation, when imperfectly established, might be for- tified by fertilizational isolation, but, in the case of plants, these are usually dependent on previous local isolation. 7. Artificial Isolation. Artificial isolation is isolation arising from the relations in which the organism stands to the rational environment. The importance of environal tsolation.—We must not assume that the various forms of environal isolation are of small influence in the formation of species because sexual or impregnational incompatibility is a more essential feature, without which all other distinctions are liable to be swept away. The importance of the environal forms of isolation lies in the fact that they often open the way for the entrance of the more fundamental forms of segregation, even if they are not essential conditions for the development of the same. Though myriads of divergent forms produced by local and industrial isolations are swept away in the struggle for existence, and myriads are ab- sorbed in the vast tides of crossing and intercrossing currents of life, the power of any species to produce more and more highly adapted variations, and to segregate them in groups that become specially adapted to special ends, or that grow into specific forms of beauty and internal harmony, is largely dependent on these factors. REGRESSIVE MODES OF THE PRINCIPLES. 12¢ 8. Environal Partition. Environal partition depends on influences quite similar to those * producing environal isolation, except that the seasonal, cyclical, and fertilizational forms are wanting. This is because these forms depend on inherited characters rather than on acquired habits, while envi- ronal partition is due to incompatibility in the acquired habits of individuals usually belonging to groups that have been locally sepa- rated fora time. Industrial and migrational partition tend more or less directly to produce groups with somewhat divergent habits, while transportational, geological, and artificial partition open the way for divergent forms of innovation, tradition, and election, to establish divergent types of habitudinal groups. Moreover, these forms of par- tition tend directly to produce isolation and consequently divergent racial groups. II. THE REGRESSIVE MODE oF EacH SEGREGATIVE PRINCIPLE. Regressive selection may be produced either by the cessation or by the reversal of a long-established form of selection. Near the end of the last chapter we referred to the Old World cuckoo and the American cow-bird as examples of degeneracy in the instincts for nest- building, for incubation, and for the feeding of their own young—a degeneracy that seems to have been produced by the gradual cessa- tion of the selection by which these instincts had for countless gener- ations been maintained. We also found that there was reason to believe that the discovery of substitutes for mother’s milk is, in certain races of mankind, leading to decay of the power to give suck, through the survival of the children of mothers who, under the con- ditions of primitive times, would have entirely failed of having any share in the parentage of the next generation of parents. Examples of the reversal of selection are found in the history of species that, through the coming and going of the ice age, have for many genera- tions been subjected to increasing cold, and then for many generations to increasing warmth. Regressive election arises when any tradition or acquired character that has long been necessary for success in a given community ceases to be so. It often prepares the way for regressive selection. For certain races of dogs the traditional methods of finding food are very different from those that were current with their primitive ancestors, and the cessation of the necessity for the strenuous life of the old times has brought regressive selection, resulting in the decay of some of the old instincts. 1340 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). What is usually called the amalgamation of races is regressive tsola- tion. Itis a form of racial demarcation, in which the boundaries are so changed that two or more slightly divergent varieties or races are interfused and become one. But, as I have already suggested, the limits within which regression of this kind can take place are compar- atively small. Regressive partition takes place when divergent forms of civiliza- tion become commingled and blended. In the case of human races it often introduces regressive isolation. The most familiar of these four regressions is regressive isolation, that is, racial amalgamation, to which Darwin’s work on cross and self fertilization has called attention. The chief significance of the prin- ciple lies in its producing a certain limited undoing of isolation and in its giving plasticity and variability to the compounded stock. Amal- gamation usually arises through the entrance of divergent races into the same region before their sexual and social instincts or the physio- logical and structural coadaptations of the sexes have become so divergent as to prevent interfusion. Under such conditions what- ever determines the bringing together of the races in the same region determines the nature of the amalgamation. When human races are brought together in the same region, the rapidity of amalgamation is determined largely by racial instincts and social conditions. 1. Reversal of Partition and Isolation in Man. The most remarkable feature in the evolution of civilized man ts the reversal of the processes of partition and of tsolation and the breaking down of the social and racial segregations that have been progressing for countless generations. The leading factors in this process of coalition are social rather than racial; but the final result will un- doubtedly be a great reduction of the number of races, and possibly a blending of all in one generalized type, resulting from the amalgama- tion of all the racesin one. It is, however, possible that the barriers preventing marriage between certain races of men will become more fixed than ever, even though the intercourse of industrial, commercial, and national life becomes increasingly intimate. The era of commer- cial intercourse has been inaugurated and will never be reversed. Again, the smaller nations are being absorbed into the larger nations; but what the final result will be on the multitude of races and castes can not be easily foretold. NO REFLEXIVE SELECTION BETWEEN GROUPS. 131 2 Isolation Prevents Reflexive Selection between Grcups. Weare now prepared to understand one reason why isolation result- - ing from indiscriminate separation is in time transformed into segre- gation. Isolation is in its very nature the suspension, not only of one jorm, but of all forms of reflexive selection between the separated portions of the species. The importance of the cessation of natural selection in producing the different stages of the degeneration of organs that have ceased to be of use has been fully discussed by Romanes (see Nature, Vol. 41, p. 437, and previous communications there referred to), who points out that, as the power of the special form of heredity by which any organ has been produced has been built up by many generations of natural selection that have acted in favor of the organ, so the gradual weakening of that power follows the cessation of the natural selection. Professor Weismann seems to appeal to the saine principle when he attributes the reduced size of ‘‘rudimentary organs’’ to the action of “‘panmixia.’’ Now, since isolation always includes the complete cessation of reflexive selection between the separate groups, a similar principle is introduced, and the result must be the weakening of the power of heredity by which the portions of the species were held in correspondence with each other before their sepa- ration. I have elsewhere shown that isolation necessarily disturbs unstable adjustments; and we here see that the most stable of the adjustments by which each part of a species is kept in correspondence with every other part gradually becomes unstable, under the con- tinued influence of isolation. Whenevera species is divided into two portions that do not interbreed, the forms of reflexive selection above described will cease to act between the two portions, and they will continue in sexual, social, physiological, and industrial harmony with each other only in so far as the force of the old heredity holds them to the old standards. But the force of heredity in these respects will in time fail if the reflexive selection that held the original stock in accord is entirely removed in its action between the two portions. If the separate breeding is long continued, incompatibility in all these re- spects tends gradually to arise; but it is manifest that incompatibility of industrial habits implies diversity in the forms of environal selec- tion shaping each portion. I therefore maintain that separation, which necessarily includes the cessation of reflexive selection between the portions separated, is a cause of segregation and divergence and that it introduces diversity of environal selection, which is a still further cause of divergence. 132 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). III. DiscRIMINATE AND INDISCRIMINATE ACTION OF THE SEGREGATIVE PRINCIPLES. * 1. Discriminate Action. Under each of these four segregative principles we may raise the question as to the difference in the results; first, when the principle under consideration is guided by some discriminative influence, continued from generation to generation, and, second, when it acts without discrimination and without cumulative results in successive generations. It is evident that discriminative survival, which is the same as selection, when continued in the same form for successive generations, must be cumulative in its effects. Dzscriminative iso- lation, that is, segregate intergeneration, arises whenever adapta- tion for appropriating certain resources brings together in one iso- lated group those that are by innate qualities and aptitudes the better adapted. In most of these cases it is not possible that another group should arise within this first group simply through being more highly endowed in the samerespect. Cumulative isolation is for the most part produced by the subdivision of groups that have already been established, and the agencies producing the successive divisions are likely to be different in their nature, and, therefore, not cumu- lative in their effects upon any one character. This, however, does not prevent each isolation from being more or less segregative in regard to some of the characters. Election, that is, the discriminate success of individuals through the attainment of certain habitudes and acquired characters, is likely to be cumulative in the effects produced on successive generations; for, as long as increased facility in the performance of certain acts is an advantage, both habitudes and aptitudes aiding in the performance will be combined in an increasing degree in each generation. Discriminate partition, that is, segregate association, arises when- ever adaptation for dealing with either the environment or the social conditions brings together in one separate group those that are by habitudes (that is, by acquired characters), the best adapted. It is manifest that among social organizations occasions producing such partition must often arise; and it seems probable that among even the least-endowed creatures great advantage must sometimes come to those who have in some degree acquired characters enabling them to meet new conditions in the environment, which come upon the spe- cies with a sweep that none who are unprepared can withstand. Such * See Table of ‘‘ Discriminate and Indiscriminate Forms,” page 136. INDISCRIMINATE ACTION OF THE PRINCIPLES. 133 changes are sometimes experienced in temperature; or in the salinity of the water, in the case of water plants and animals. 2. Indiscriminate Action of the Segregative Principles. Again, let us consider what the results are when the action of these principles is indiscriminate. IJndiscriminate survival takes place in regard toany given character of aspecies when the presence or absence of the character has no effect on the adaptation of theindividual. For Anglo-Saxons the possession of blue eyes or gray eyes is a matter of non-selective importance, and selection does not determine which shall prevail. There is, however, another form of indiscriminate survival which may have definite influence in determining the subsequent form of araceorspecies. I refer to the indiscriminate destruction of all but a small portion of the intergenerating group. Against heavy volcanic convulsions the varying endowments of different individuals of any one species usually count for nothing, and therefore the destruction falling upon them is indiscriminate; but if only a pair or two are left to propagate the species, the probability is that the type will be more or less changed in one or more of its characters. Indiscriminate vsolation of only a small fragment of a species is liable to result in important divergence in one or more of the characters of the species. Ifa single gravid individual, of a variable species of Hawaiian tree snails, is carried for a mile or two from its native val- ley while clinging to a leaf borne by a bird or a strong wind, it may fall in a neighboring valley, among groves and thickets of the same trees and shrubs that furnished its natural station in its original home. Is there now any probability that the colony descending from this individual, completely isolated from the original stock, but living in a valley with the same climate, and vegetation, and birds, and insects as are found surrounding their relatives in the original valley, will, by any chance, reproduce all the variations and varie- ties of the original species, and in the same proportions, and at the same time avoid producing any new varieties? My knowlege of var- iable animals in general, and my observations on Hawaiian snails in particular, make it impossible for me to believe that such a case could everoccur. If anyone says that an isolated portion of a species under absolutely the same environment as the original stock must produce the same varieties, as Wallace maintains in his volume entitled ‘‘ Darwin- ism,’’ I suspect he is using the word “‘ environment ”’ as equivalent for all the conditions that may cause divergence, whether they lie within - the species or belong to what lies outside of the species. This seems to bein part the explanation of Wallace’s position ; for in enumerating the 134 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). conditions in the environment that may have an effect in producing divergence, he calls attention to the fact that the small isolated por- tion of the species ‘‘is at once in a different position as regards its own kind.’’ Now, this is exactly what I mean when I say that the iso- lation of a small portion has some effect in producing divergence, even if the conditions outside of the species could be absolutely the same as in the original habitat. Still further, as I have abundantly shown in the paper reproduced in Appendix II, it is very possible that the isolated portion will, early in its career, if not from the very first, be subjected to new forms of selection, through the adoption of habits of feeding that are wanting, or unusual, in the original habitat; for a rare habit in the original valley might become the predominant habit in the colony that arises in the newly occupied valley, even if the envi- ronments were absolutely the same. ‘This form of selection I have called active (or endonomic) selection. Indiscriminate success will arise in regard to any given habitude, or form of acquired efficiency, when the attainment or the non-attain- ment of the habitude has no effect on the success or influence of the individual. Another form of indiscriminate influence may be intro- duced by the indiscriminate slaughter of all but a few individuals of a community, in which case the habits of the few remaining indi- viduals will have great influence on the habits of the new community arising through the multiplication of the few sui vivors. Indiscriminate partition arises whenever the occasion that brings a number of individuals of a species together in a separate position does not determine that they shall be of any particular type of habitudes, of culture, or acquired skill. Partition due toan island being divided by partial submergence is usually indiscriminate; while migration often produces discriminate partition, as when it brings to a distant island men who are skilled in canoe building and sailing. 3. Contrasts in Discriminate and Indiscriminate Forms of Action. These considerations bring to light the following facts: (1) In the survival of innate characters and the success of acquired characters the discriminate forms (7. e., selection and election) are of prime importance; for in one way or another they are continually acting on nearly every generation of nearly every species. The cases must be rare in which equal success and survival are attained by all the variations; for if variations in other respects have no effect, its variations in vigor will have relation to the degree of survival. In some rare cases there will occur the indiscriminate elimination of all but a very few members of a race or species; and the results DISCRIMINATE AND INDISCRIMINATE ACTION. 135 in such cases are liable to be of importance, through the original average character of the species not being fully represented and through the fact that this initial bias often leads to some new form of selection, which continues to act with cumulative force through subsequent generations. No single pair can exactly repro- duce the average character of the species in all its aptitudes and habitudes, and therefore the methods of dealing with the environ- ment adopted by the descendants are liable to be different. (2) In isolation and partition there is less opportunity than in selection and election for cumulative effects in each generation. Moreover, in many of the cases, the isolation is indiscriminate till divergent forms of selection codperate. But it should be noted that the isolation of a small number of the species is of frequent occurrence, and the failure of these small groups to represent the average charac- ter of the group or race either in habitudes or aptitudes introduces slight divergences determining new forms of autonomic selection which are of great importance in molding new types. And even when large masses are indiscriminately isolated all selection pro- ducing codrdinations between the members of the separate groups ceases; and the probability is that in the course of many generations divergent forms of selection will arise, through different methods of coérdination between members as well as through different methods of dealing with the environment adopted by different isolated groups. This probability rests not so much on the probability of a difference in the average character of the two large sections as on the probability that in one section some new habitude will arise that does not arise in the other section. The importance of isolation in producing diver- gence is seen not only in its being the absolute condition on which divergent forms of selection become of avail in producing divergence, but in the fact that the isolation of a few individuals often introduces from the first a divergent form of autonomic selection, though the environment is the same, and in the fact that the isolation of a large section of a species opens the way for a similar divergence of selection, though it may require many generations for the result to become apparent. Moreover, discriminate isolation (as when different indus- tries have led individuals to form intergenerating groups according to their aptitudes), leads from the first to divergence in adaptations and to the intensification of adaptations. The table on page 136 will be useful in enabling us to keep in mind the importance of these distinctions when applied to some of these prin- ciples. Discriminate survival, which is usually called selection, is of such importance that many terms have been needed to present the 136 ANALYSIS OF THE FOUR PRINCIPLES (CONTINUED). different influences through which it arises; while indiscriminate survival and its equivalent, indiscriminate elimination, seem to be sufficient for the designation of a process which, as compared with selection, is rarely effective in producing the transformation of races. 4. Table of the discriminate and indiscriminate jorms of the four segregative principles. Ture EIGHT ForRMS. THE RESULTS. PARTITION. . Discriminate partition = segregate asso- ciation, . Indiscriminate partition with more or less loss of power to perpetuate the original habitudes unchanged. SUCCESS. . Discriminate success = election. . Indiscriminate success = indiscriminate failure. ISOLATION. _ Discriminate isolation = segregate inter- generation. . Indiscriminate isolation with more or less loss of power to reproduce the complete average of the innate characters ot the orig- inal stock. SURVIVAL. . Discriminate survival = selection. . Indiscriminate survival = indiscriminate elimination. ————— . Grouping of individuals according to habi- tudes and acquired characters, and so producing habitudinal segregation, and giving an initial tendency toward segre- gate breeding. . More or less divergence in the habitudes and acquired characters of the separated groups, especially when the groups are very small, and so producing initial habi- tudinal segregation. . Success and influence of individuals accord- ing to their acquired fitness for the condi- tions, both social and physical, in which they are placed, producing intensified habitudinal segregation. . When the number of individuals that es- cape from a sweeping catastrophe is very small, they will be unable to perpetuate the original social organization unchanged. . Grouping of individuals according to their aptitudes and innate characters, and so directly introducing segregate breeding with divergence of characters, 7. e., racial segregation. . More or less divergence in the aptitudes and innate characters of the isolated groups, especially when at the time of the first setting apart the group is represented by but one, or but few, individuals, and so producing initial racial segregation. . The efficiency of individuals in living and propagating will vary (and so their survi- val will vary) according to their innate fitness for the struggle of life, and thus the fitness of the race will be increased. . When those indiscriminately surviving are very few, it will be impossible for them to reproduce all the innate characters of the original stock unchanged. CHAPTER VILE CLASSIFICATION OF THE FORMS OF THE PRINCIPLES PRODUCING ALLOGAMIC EVOLUTION. I. TABLES OF FORMS, WITH BRIEF EXPLANATIONS The analysis presented in the two preceding chapters has revealed many factors, which are here brought together in tables so arranged as to show the more important of their relations to each other. (See pages 138-139.) 1. Allogamic, Autogamic, and Agamic Evolution. A complete classification of the factors of organic evolution must include the principles producing differentiation of organisms multi- plying asexually, as wellas of those reproducing sexually. Moreover, the reproduction of self-fertilizing speciesis so unlike that of speciesin which cross-fertilization takes place (either in each generation or at the end of a series of generations), that it seems necessary to consider their methods of transformation separately. Following these dis- tinctions, organic evolution needs to be divided into three depart- ments, which may be called: Allogamic evolution, which relates to the evolution of cross-fertiliz- ing organisms; Autogamic evolution,* which relates to the evolution of self-fertil- izing organisms; and Agamic evolution, which relates to the evolution of organisms whose reproduction is continuously asexual. The investigation presented in this volume relates to allogamic evolution. * Karl Pearson, in 2nd ed. of ‘’The Grammar of Science,’ London, 1900, p. 423, uses the term “Autogamic Mating”’ to designate self-fertilization. 137 138 CLASSIFICATION OF THE FORMS OF THE PRINCIPLES. 2. Allogamic Evolution Controlled by the Four Principles of Segregation. / Sr autonomic association III, and heteronomic association = V + VII, controlled by segregate association of individuals according to their ac- quired habitudes and resting on tradition and innovation, with habitudinal generalization and accommodation. B. Habitudinal segregation ’.’ Cc. Typal demarcation *." autonomic demar- cation = 1+ II, and *." heteronomic demar- cation = V+ VI. (E) Habitudinal demarcation, through par- tition. {a. Reflexive partition. } 1, Conjunctional partition. (1) Family partition. (2) Social partition. 2. Institutional partition. (3) Linguistic partition. (4) Religious partition. | (5) Educational partition | (6) Sanitary partition. | 1 b. Environal partition. | 3. Endonomic partition. (7) Industrial partition. (8) Migrational partition 4. Heteronomic partition. ‘moried ommouojny “[ Coincident partition. Ai) } (9) Transportational par- | tition. w (10) Geological partition.w | (11) Artificial partition. J Lc. Regressive partition. w. Indiscriminate partition. ‘u0T} -IqIed o1mou -O19}9H “A D. Typal intensification *." autonomic intensifica- | tion = III + IV, and °.. heteronomic intensifi- | cation = VII + VIII. (G) Habitudinal intensification through success (through election when discriminate). { g. Reflexive election. ) | 10. Conjunctional election. | (29) Sexual election. | (30) Social election. (31) Filio-parental election. 11. Dominational election. ) ’ —_ — Pay > ES 5 12. Institutional election. 2 os (32) Religious election. L 3 = (33) Educational election. | ee 2 (34) Sanitary election. heey o (35) Penal election. ehh Mo] R : bee -3 | kh. Environal election. i 9 eI 13. Endonomic election. B OF (36) Habitudinal election. | (37) Aptitudinal election. J 14. Heteronomic election. VII. Hete- (38) Natural election. } ronomic (39) Artificial election. election. | 2. Regressive election. y. Indiscriminate failure. | \ | | II + IV, and heteronomic in- | tion of indviduals dity and variation, with ve r ergene here segregate int autonomic intergeneration VIII, controlled by according to their innate aptitudes and resting on racial generalization and adaptation. } + Racial segregation °." tergeneration = VI A. (F) Racial demarcation through isolation. d. Reflexive isolation. ) 5. Conjunctional isolation. (12) Sexual isolation. (13) Social isolation. 6. Impregnationai isolation. (14) Dimensional isolation. (15) Structural isolation. Physio- ;(16) Potential isolation. logical / (17) Segregate fecundity. isolation | (18) Segregate vigor. (19) Segregate adaptation , (20) Segregate freedom from competition. (21) Segregate escape from enemies. 7. Institutional isolation. ( @ Environal isolation. 8. Endonomic isolation. (22) Industrial isolation. (23) Chronal isolation. Seasonal isolation. Cyclical isolation. (24) Migrational isolation. J ‘II *‘WOT}L[OST OIuLOMO NY i 9. Heteronomic isolation. } (25) Transportational iso- | lation.x (26) Geological isolation.x [ | J Coincident isolation. (27) Fertilizational isola- tion. (28) Artificial isolation. f. Regressive isolation. L x. Indiscriminate isolation. “MOT}LIOSI Pyseaco)econs “939H “IA | (H) Racial intensification through survival (through selection when discriminate). j. Reflexive selection. } 15. Conjunctional selection, (40) Sexual selection. (41) Social selection. (42) Filio-parental selection. 16. Dominational selection. (43) Sustentational domination. (44) Protectional domination. (45) Nidificational domination. (46) Mating domination. (47) Prepotential domination. 17. Impregnational selection. (48) Dimensional reflexive se- lection. (49) Structural reflexive selection. (50) Potential selection. (51) Fecundal selection. 18. Institutional selection. (52) Ecclesiastical selection. (53) Military selection. (54) Sanitary selection. (55) Penal selection. | 19. Prudential selection. k. Environal selection. 20. Endonomic selection. l (56) Habitudinal selection ‘HOLOVJes OImMIOUOINY “AT AS Coincident (or organic) selection. (57) Aptitudinal selection J 21. Heteronomic selection. VIII. He- (58) Natural selection. \ teronomic (59) Artificial selection. selection. 1. Regressive selection. z. Indiscriminate elimination. rn rere TE EE tfOrganic (or Coincident) selection is determined by accommodation that protects the group from extinction till coincident variations have time to arise. TABLES OF FORMS. 139 3. The Forms of Selection Defined. j. Reflexive selection, based on relations within the group. > #115. Conjunctional selection, *.. codperation of individuals especially °.. the co6rdination of instincts and habits with qualities. (40) Sexual selection’. codrdination of sexual instincts and qualities. (41) Social selection *.. co6rdination of social instincts with qualities. *+(42) Filio-parental selection *.’ cobrdination between the powers and char- acters of the parents, and the size, number, form, and instincts of the young. 16. Dominational selection’ ." power to outdo, outrun, and overcome others of the same group in appropriating needed resources. (43) Sustentational domination *.. taking food. (44) Protectional domination *.. taking positions affording safety. (45) Nudificational domination. taking positions for breeding. (46) Mating domination *.. monopolizing mates. (47) Prepotential domination ‘." superior potency of pollen. *17. Impregnational selection *.. structural and physiological coordinations that secure a sufficiency of impregnated germs with least waste. (48) Dimensional selection ’.. cobrdination in length of pistils and pollen tubes, and in size of other impregnating organs. (49) Structural selection’. codrdination of clasping organs, ete. (50) Potential selection ‘.* codrdination of the sexual elements. (51) Fecundal selection *.. cobrdination in the relative number of the male and female elements preventing waste. 18. Institutional selection *.. suppression of reproduction for (52) Eccle- siastical, (53) Military, (54) Sanitary, and (55) Penal reasons; or the favoring of certain types. t19. Prudential selection’. delay of marriage and prevention of reproduction for economic and other personal reasons. k, Environal selection *.: relations of the group and the environment. 20. Endonomic selection, determined by activities in the group. (56) Habitudinal selection, determined by acquired habitudes. *(57) Aptitudinal selection, determined by innate aptitudes. t21. Heteronomic selection, determined by activities in the environment. (58) Natural selection, determined by the irrational environment. (59) Arttficial selection, determined by the rational environment. §/. Regressive selection, as when accommodation preserves those of inferior racial endowments. Explanation of the signs used in Sections 2 and 3. = Equalto. + Combined with. *. By means of; produced by; through. * Determined by previously attained aptitudes. + Determined by previously attained habitudes. *{ Determined by aptitudes and habitudes. t Determined by conditions in the present environment. § Determined by one or more of these influences. J ; ‘dnos3 yova Jo sapnande pue sapnzyiqey ay} Aq pouruntajap ‘woysajas o1mo0UonY “AT ly» ‘TITAL 140 CLASSIFICATION OF THE FORMS OF ‘THE PRINCIPLES. 4. Conditions Determining the Forms of Selection. The forms of selection depend on the following conditions (the letters and numbers are those used in the tables on pages 138-139): j. The relations in which individuals of the same group stand to each other; that is, the reflexive conditions. First, the aptitudes (1. e., instincts and other inherited powers), that shape these relations to each other; second, the habitudes (7. e., habits and other acquired powers), that shape their relation to each other; and, third, the physical characters of the individuals, must be codrdinated. k. The relations in which the group stands to the environment, that is, the environal conditions (arising from the action and reaction be- tween the group and its environment), must be harmonized. 20. The conditions within the group that shape these relations to the environment; that is, the endonomic conditions, being (56) the habitudes, and (57) the aptitudes that enable the isolated group to determine how it will use the environment, must be kept in the fullest possible accord with these uses and with each other. 21. Heteronomic conditions, (58) natural and (59) artificial; that is, conditions in the environment that constitute a limit to the possible methods of escape from destruction. Small colonies of Hawaiian snails, of the same species, isolated in neighboring valleys, but occu- pying the same species of trees and feeding in the same way, and all exposed to the same enemies, it seems to me are probably subject to the same forms of heteronomic environal selection. Any snail, capable of living on several species of trees growing in thick, shady groves, when brought to a valley where only one species of such trees is found, is subjected to heteronomic conditions, for but one method of survival is open to it. But even under these conditions we find divergence taking place in isolated groups. Shall we attribute such divergence to diversity of selection or to the diversity presented in the average character of the groups when first isolated? I believe this latter explanation is the more reasonable. If each colony was originated bya single snail, we knowit is impossible that these original progenitors of the different colonies should in every respect have possessed the same characters. It is also impossible that the varia- tions occurring in an isolated colony springing from a single pair should be exactly the same variations, presented in exactly the same proportions, as in the mother colony from which they were separated. The influences determining the forms of isolation, partition, and election are also presented under the aspects of reflexive influences and environal influences, and in constructing terms for the different AUTONOMIC AND HETERONOMIC INFLUENCES. I4I forms of these three principles we are able to avail ourselves of the adjectives that have been used in designating the different forms of selection. This is a great aid in presenting the relations between the ‘four principles in their different forms. In many of the places where the sign *.: (meaning caused by) is used after the forms of reflexive selection, it might with equal correctness be changed to .’. (meaning causing). For example, social selection may be described on the one hand as depending on the codrdination of social instincts and qualities, and on the other hand as buzlding up and maintaining the social instincts and the characters on which they depend. ‘Taking a special case: Without any possible method of recognizing each other there could be no social selection; but, on the other hand, when a new race is formed, it is social selection that seizes on some new and fluctuating character, emphasizing, intensifying, and rendering it permanent; and so, in an important sense, it may be said that social selection produces the recognition marks and calls and coérdinates them with the special instincts of the race that recog- nize these marks and respond to these calls. II. AUTONOMIC AND HETERONOMIC INFLUENCES. 1. Autonomic Influences Include Endonomic and Reflexive Influences. The nomenclature given in this volume calls attention to the fact that endonomic selection is determined by habitudes and aptitudes for dealing with the environment, and is subject to diversity without any corresponding diversity in the environment; and that the forms of reflexive selection are determined by the necessity for sexual, social, and other codrdinations between the members of the same intergen- erating group, also undergoing change without reference to change in the environment. The forms of endonomic and reflexive selection are, therefore, brought together under the term autonomic selection, which sets them in strong contrast with heteronomic selection, which is always determined by conditions in the environment surrounding the intergenerating group. But the effects of changes of activities within the intergenerating group, and not depending on changes in the environment, are not all covered by autonomic selection. We must also consider the autonomic forms of ‘tsolation, election, and partition, for they are all of importance in segregating and molding the types of allogamic organisms. Autonomic isolation includes both endonomic isolation, produced by industrial, chronal, and migrational isolation, and reflexive isola- tion, produced by sexual and social instincts, by impregnational incompatibilities, and by institutional requirements. Itisin contrast with heteronomic isolation, which is determined by conditions outside 142 CLASSIFICATION OF THE FORMS OF THE PRINCIPLES. of the organic group, as, for example, geological subsidence, or causes resulting in transportation to an isolated position. Autonomic selection codperating with autonomic isolation produces autonomic generation; and heteronomic selection codperating with heteronomic isolation produces heteronomic generation. Autonomic election includes endonomic election, produced by the success of different acquired methods of dealing with the environment, and reflexive election, produced by the social promotion or suppression of individuals according to the success of their habits in relation to others of the same group. It is in contrast with heteronomuic election, which is determined by conditions outside of the organic group. Autonomic partition includes endonomic partition and reflexive partition, and secures the grouping of individuals as regards their habitudes, through the influence of activities that lie within each asso- ciating group. It isin contrast with heteronomic partition, which is the grouping of individuals as regards their habitudes, through the influence of activities in the environment. Autonomic partition combining with autonomic election produces autonomic association; and heteronomic partition combining with heteronomic election produces heteronomic association. Habitudinal intensification may arise from activities entirely within the group of organisms, of which social promotion and social suppres- sion* of habitudes are familiar examples, and the combined effects of these activities on the habitudes of the group is appropriately called autonomic election; but we need a term to designate the combined influence of autonomic election and autonomic selection, producing the intensification of inherited aptitudes, in addition to the intensifica- tion of acquired habitudes. Such a term is autonomic intensification. It signifies the molding of types by activities within the intergene- rating and associating group. Incontrast with autonomic intensifi- cation, we have intensification produced by the combined action of heteronomic election and heteronomic selection, which may appro- priately be called heteronomic intensification. The codperation of autonomic partition and autonomic isolation I call autonomic demarcation; and the codperation of heteronomic partition and heteronomic isolation I call heteronomic demarcation. The codperation of autonomic intensification with autonomic demarcation produces autonomic segregation; and the cooperation of heteronomic intensification with heteronomic demarcation produces heteronomic segregation. * Baldwin defines social suppression as ‘‘Suppression of the socially unfittest by law, custom, etc.’’ (See ‘“‘Social and Ethical Interpretations,” Appendix B.) PARTITION CONTROLLING ISOLATION. 143 2. Autonomic Partition Produces Autonomic Isolation. In the evolution of the European races of man the tendencies which _ break down ancient segregation, whether resting on habitudes or aptitudes, are so strong that it is difficult for us to apprehend the conditions of society in which segregative tendencies are in full force. The caste system of India not only maintains with absolute strictness the old barriers based on traditions received from remote genera- tions, but tends to create new divisions, resting at first on industrial habits, but in time reinforced by separate social customs, separate ideals, and separate methods of training, and are finally intrenched behind restrictions forbidding marriage with those who were once considered as belonging to the same caste. Professor Reinsch states* that there are no less than 3,000 castes in India; and missionaries who have studied the institutions of the country most carefully assure us that if a caste is defined as an intermarrying group that is completely excluded from marriage with all other groups, then the castes of India number many thousands. Of the Brahmins, who are considered the highest caste of India, there are over 1,800 such sub-castes. Rev. J. P. Jones, D. D., of Pasumalai, South India, informs me that during his residence in Southern India a branch of a certain barber caste has taken up the trade of weaving; and feeling that their occu- pation, which is being transmitted from father to son, sets them above the barber caste, they are now beginning to require that the son of a barber desiring to marry the daughter of a weaver must give up bar- bering and become a weaver. The one remaining step required for the full establishing of the new caste will probably come within a few years, and will be the objecting to additions to the guild from those who have not been born within its ranks. ‘Though railroads and other influences from Europe tend toward freer intercourse, these new castes are struggling into exist- ence; and the tendency is to fortify the spirit of segregation by refus- ing to eat or have close fellowship with any outside of the caste that has thus recently come into being. The caste system as developed in India is as unlike the democratic conservatism of China as it is opposed to the progressive individual- ism of Europeanraces. It may be doubted whether the caste system of India can ever develop into a truly progessive system. But the essentially democratic life of China stands in a very different relation to the progressive element of European civilization. In innate racial qualities no people can surpass the Chinese; and their vitality and power of adaptation is such that they seem to be equally fitted for suc- * See ‘‘ The Forum”’ for June, 1901. 144 CLASSIFICATION OF THE FORMS OF THE PRINCIPLES. cess in all climates and inall countries. Moreover, under the stimulus of intercourse with European civilization, there are evident signs that new and progressive elements will be added to the old ideals tilla truly progressive spirit is attained. The remarkable power of accommoda- tion to different climates and health conditions possessed by the race, especially by the branch occupying the southern provinces of China, is such that few races are able to endure free competition with them even when the country and climate are so chosen as to give the best pos- sible chance to their rivals. Members of the Teutonic race, when sub- jected to the climate of India, suffer from the effects of the heat; and their small power of individual adaptive modification in that direction gives them but little prospect of becoming completely adapted through the effects of natural selection; for, if their children remain contin- uously in the country, they have not sufficient energy for the battle of life. On the other hand, the Chinese from Canton, with high powers of accommodation, are fully successful as permanent settlers, both in the cold of Manchuria and in the heat of the Malay Peninsula, Borneo, and the Philippine Islands, and if completer racial adjustment is needed, they are sure to attain to it in the course of generations, through the accumulation of coincident variations. In the last chapter of his Problems of Evolution, Headley discussed from a biological point of view some of the problems arising in the intercourse of eastern and western races. III. AN UNWARRANTED ASSUMPTION. In discussing the influences producing evolution some writers have assumed that all diversity of survival in different groups of individ- uals of the same species is due to diversity in the environments to which the groups are exposed; and as natural selection is defined as the influence of the environment in determining what individuals shall survive, the inference is reached that diversity of natural selection is the only influence producing diversity of survival. A careful study, however, of causes producing diversity of survival in isolated groups shows that this assumption is without foundation. In the first place, it ignores the fact that diversity in sexual selection, and in any one of the other forms of reflexive selection, depends on diversity in the influence of members of the group upon each other, and that these influences may pass through a considerable range of divergence without change in the conditions lying outside of the species. In the case of man the forms of reflexive selection depend chiefly on the form of social organization, which may be subject to great change without reference to change in the environment of the AN UNWARRANTED ASSUMPTION. 145 group. In the second place, it ignores the fact that diversity of envi- ronal selection may be brought about either by diversity in the activ- ities of the environment (that is by heteronomic selection), or by diversity in the organism determining its methods of dealing with the environment (that is, by endonomic selection). Small differences may of course be found in the conditions presented in any two isolated positions; but when the divergence in the groups of organisms is not in accord with nor in proportion to these, it can not be attributed to them. If, however, we find that the form of selec- tion is determined by the methods of using the environment adopted by the group, and that this is determined by the innate aptitudes of the individuals that founded the colony, I call the principle aptitudinal selection. If again, the method of using the environment, and so the form of selection, is determined by the training and acquired habits of those founding the group, I call the principle habitudinal selection. Still further, there are strong reasons for believing that divergent forms of survival may arise in isolated groups, not only when the envi- ronment surrounding each group is the same, but when the habitudes and aptitudes of the individuals establishing the groups are the same. If we select two islands as completely alike in climate and resources as can be found, and plant upon the same two colonies of a few families each, selected in such a way that the average character of the colonies, in both innate and acquired characteristics, shall be as much alike as possible, and if we then subject them to complete iso- lation from each other and from the rest of the world, will they not in a few generations become divergent in language, in dress, in customs, in industries, and, if the experiment is continued through scores of gen- erations, even in race characters? This might be called spontaneous diversity of election in partitioned groups, producing divergence of habitudes, and finally divergence of habitudinal selection, and so divergence in race characters. In Professor Conn’s Methods of Evolution, 1900, will be found a very lucid statement of the importance of isolation as a primal factor in all divergent evolution; but his plan of exposition aims at giving in broad outlines the main factors, rather than a complete analysis of the influences producing each. Av ons , sine a i} at rt ‘I an Ve i ; A A ath j ih ed vii BA Ns W He iu Ny A rn (i ay vi i iy oe uA i for i wie Ah iA me iy A At hs no a wie re i A ‘ nh rh Ae an , i iy Me ealuepilinty me Mia 1 Pl i i ia sii 4 ne t iw helt aw ne ea My HP Nakge ‘yh a) NS eh ee ya : : \ y rh 4 “a , th ili) aA Ny y ‘ we Tay ‘i NACA | i ‘es te huh nd eae CHAPTER IX. SUMMARY AND CONCLUSION. I. SuMMaRY. 1. Segregation. As segregate breeding is the fundamental principle producing racial segregations, and as isolation and selection codperate in controlling the degrees and forms of segregate breeding, and therefore in control- ling variation and heredity, so also it will be found that segregate association is the fundamental principle producing habitudinal segre- gation, and so partition and election coéperate in controlling the forms of segregate association, and therefore in controlling innovation and tradition. It is also evident that the initial racial segregation introduced by discriminate isolation, or by the indiscriminate isolation of a few pairs, may be greatly hastened and intensified by the exposure of the isolated groups to diverse forms of selection; and it is no less certain that, even when the environment is virtually the same, diverse forms of selection may be introduced by diverse methods of using the environ- ment that are liable to be adopted by the isolated groups. Moreover, it is equally evident that the initial habitudinal segregation intro- duced by discriminate partition, or by the indiscriminate partition of a single pair, may be greatly hastened and intensified by the exposure of the separated groups to diverse forms of election arising from the various forms of success, which are determined by the activities that become habitual in each group. The evolution of organic types is originated and maintained by partition and election producing habitudinal segregation, and by isolation and selection producing racial segregation. Without these principles producing their intensifying and ramifying effects on organic types, the complex world of life could never have arisen out of the simple forms of primitive life; and without the continuance of the segregations thus produced the diversity that has been reached would soon be dissolved and the whole world of life would be reduced to but one species. But the history of races and species shows, on the one hand, that segregate breeding when fully fortified by physiologi- cal and psychological incompatibilities is never removed; and, on the other hand, that whenever increasing stringency of segregate breed- ing is in any way introduced, there we have either the transforma- 147 148 SUMMARY AND CONCLUSION. tion of some existing species or the setting apart of new groups that grow into new species unless reabsorbed by crossing or exterminated by competition. The whole process of bionomic evolution, whether progressive or retrogressive, whether increasingly ramified and divergent, or increas- ingly convergent through amalgamation, is a process by which the limitations of segregate breeding are either set up and established or cast down and obliterated. But, as we have already seen, on the side of amalgamation an impassable barrier is in time reached in the physiological and psychological incompatibilities of long-established types, while on the side of advancing segregation the possibilities are constantly increasing. The general result is that new isolations and incompatibilities are constantly arising, forming new races and species, which in time become so divergent that it is impossible for them to coalesce under any conditions. 2. Unbalanced Propagation. If we wish to find a principle which, if continued from generation to generation, will steadily tend towards the transformation of type, it is unbalanced propagation continuously of the same sign. That is, if the result desired is increase of the character under consideration, the selection in successive generations must be of those individuals that possess the character in more than the average degree; and such selection may be said to be continuously of the plus form. If the in- dividuals selected in each generation depart from the type, but are so selected that those above the average are exactly sufficient to balance those from below the average, the average character of the mixing mass will be the same as the average of the original stock; and again, if the selection is plus in one generation and equally minus in the next generation, the result will be uncertain, even though long continued, for the effects of selection in one generation will be balanced by the effects of selection in the next generation, and we shall have one form of balanced selection. Witha definition of balanced propagation that includes balancing of both the kinds just mentioned, we may say with confidence that unbalanced propagation, if continuous, will produce transformation, and that balanced propagation of the type, if con- tinuous, will produce stability of type, and that balanced propagation of forms, some of which are considerably above the type and others of which are considerably below the type, will produce fluctuating variation. We may next ask, how is unbalanced propagation brought about? The answer is that, in both natural and artificial breeding, it may be UNBALANCED PROPAGATION. 149 brought about either by the unbalanced effects of the processes sepa- rating the individuals into coexistent groups that are prevented from intergenerating, or by the unbalanced effects of differing degrees of " survival for different forms of variation. The former principle is called “‘isolation,’’ and the latter principle ‘‘selection.”’ It is quite evident that in as far as selection prevents any form from propagating, in so far it prevents intergeneration between that form and the forms that produce the next generation; but, at the same time, I prefer to define isolation as the prevention of free crossing between coexisting groups, though the individuals of each group, so far as they survive, are freely intergenerating. When pointing out the correspondences between selection and isolation, I would say that both are principles by which the abiding principle of segregate breeding is modified and intensified; and that when either of them produces unbalanced propagation effected by the same signin successive generations, the result is transformation of type. During the process of domestication the reproductive powers of many species are so impaired that it is with difficulty that a perma- nent domestic race can be produced. Many individuals that thrive on the nourishment furnished fail to leave offspring, so that the race is perpetuated not by the offspring of those which are most pleasing to those who keep and select them, but by the offspring of those which have offspring. The same principle may produce transformation in species that are not under domestication. For if, among the many varieties, there arises one that, while retaining equal adaptation, is more fruitful than other varieties, it will be favored by fecundal selec- tion. ‘The descendants of the most fertile will have the largest share in producing the next generation. This will tend to produce increas- ing fecundity in succeeding generations. This isa form of discriminate survival; but we must remember that this fecundal selection will pro- duce accumulation of other characters besides fecundity only when fecundity is correlated with certain variations that do not represent the typical or average form; that is, only when it is unbalanced fecun- dity. This seems to be a necessary law. Asa corollary from this law, I judge that, in a stable intergenerating species or variety, the aver- age form will be found to be most fertile; or, at least, the forms that depart from the average will not be continuously endowed with higher fertility than the averageform. In considering the effect of selective survival we have to discriminate between balanced and unbalanced selection. Unbalanced selection is either the selection of individuals above the average producing an increase of the character thus selected or the selection of individuals below the average producing a decrease 150 SUMMARY AND CONCLUSION. of the character thus discriminated against. Balanced selection is usually secured by selecting individuals of the average form, and tends to produce increasing stability. 3. Cumulative Effects through the Cooperation of Different Principles. Two or more of the factors mentioned in this volume may co- operate in rendering a type more stable, or in rendering its previously attained characters more intense, or in diminishing its present char- acteristics while others are brought into prominence. If the organ- isms under consideration form but one intergenerant, any transforma- tion thus produced will be monotypic; butif through the codperation of isolation they form several intergenerants, any subsequent trans- formation will result in polytypic evolution. Again, if each factor working by itself would tend to produce the same result, the united influence of several factors working together will be much more decisive than that of but one of them working alone. 4. Cumulative Effects through the Operation of the Same Principle in Successive Generations. Once more it should be noted that the effect of unbalanced selection when continued through many successive generations is vastly greater than when lasting but for one generation. Indeed, on reflec- tion it becomes apparent that the great difference between selective survival and non-selective survival is that the former is continuous from generation to generation, while the latter is accidental, and, therefore, not continuous. Moreover, in non-selective survival the effects of survival in any one generation are liable to be in a measure neutralized by the effects of survival in succeeding generations. Dis- criminate isolation is more effective than indiscriminate isolation because it is more effective in bringing together in one groupa consid- erable number of individuals that belong to the same class; that is, that are either of average character, or above the average, or below the average. Indiscriminate isolation is less likely to bring together a special type and to repeat the process through many generations, and is, therefore, usually less effective than discriminate isolation in producing transformation. The probability that a cumulative result will be reached through the effects of indiscriminate isolation, dividing the whole species into two large and nearly equal groups, without the codperation of selec- tion or without the continuous and cumulative effects of suetude (7. e., of use or disuse), is very small; but we must remember that when isolation has become effective in shutting out all individuals of other groups, divergent selection, divergent suetude, and different forms SOME OF THE FACTS EMPHASIZED. 151 and degrees of amalgamation are liable to arise. This liability is enhanced in case the fragment indiscriminately separated is small; for there is then a possibility that, in some one of its habitudes or aptitudes, it will differ from the original stock in such a way as to insure its using the environment in a somewhat different manner. It is certain that isolation is a principle tending toward the introduction of diversity not only in the forms of environal selection affecting the species, but also in the forms of reflexive selection, of suetude, and of amalgamation. The distinction indicated by discriminate and indiscriminate isola- tion pertains only to the generations when group-formation is being shaped by additions brought in from the parent stock or from other groups, and these are usually the earlier generations of the new groups; but the influence of this primal shaping will continue through subse- quent generations. The action of discriminate survival and of suetude is, however, not at all confined to the earlier stages of group formation. 5. Amalgamation. After a group has been considerably differentiated, combination with other groups is described as amalgamation. Amalgamation, or the crossing of races that have been segregated for many generations, is a most effective process for introducing varia- tion ; and, if the contrast is not too great, for adding vigor to the stock. 6. Some of the Facts Emphasized in this Volume. (1) That segregation is the underlying principle throughout the whole process of bionomic evolution. (2) That the causes producing and intensifying segregation are quite various, and can not all be included under the term “ selection,’ and that in seeking the causes of organic evolution we must investigate all the natural causes modifying the action of segregate breeding. (3) That some of the most powerful influences in the control of seg- regation are due not to different forms of activity in the environment, but to diversity of activities in the organism, and may, therefore, be classed as forms of autonomic segregation. (4) That habitudinal demarcations, through partition, are the initial forms of grouping, which, when intensified by election, produce habitudinal segregations, and that habitudinal segregations are often the controlling factors leading to racial segregations. (5) That in reflexive selection (that is, selection produced by the relations of members of a species to each other), the influence of the environment in producing the special result is usually very obscure, 152 SUMMARY AND CONCLUSION. though there can be no doubt that it is sometimes operative. Social organization is often affected by the conditions in the environment; but though the environment remains unchanged, vast changes in social organization may take place. For example, while remaining in the same region, and without special change in the environment, a tribe of men may pass from the hunter stage of life, through some- thing of pastoral life, into agricultural and diversified industrial life. This has probably been the experience of the Chinese race. (6) That endonomic selection, resting on the power of different individuals of the same species to deal with the same environment in different ways, is a fruitful cause of divergent evolution in isolated sections of the same species. This diversity of power is sometimes due to diversity of aptitudes, producing what I call aptitudinal selec- tion; and sometimes to diversity of training and of habitudes, pro- ducing what I call habitudinal selection; and at still other times to different methods of using the same aptitudes and habitudes, for which a suitable name has not yet been suggested. (7) That organic (or coincident) selection is of great importance in securing a new adjustment when the organism is suddenly exposed to an environment very different from that to which it was previously adjusted. (8) That the indiscriminate isolation of a small fragment of a species leads directly to the modification of type in the descendants of the isolated fragment, for the character of a single individual (or even the average character of several individuals) seldom if ever represents the average character of the original stock in every respect. (9) That indiscriminate isolation of a large section of aspecies interrupts the unifying influences of tradition and of heredity between separated branches of the original stock ; and, even though the environ- ment surrounding each branch is the same, the traditional method of dealing with the environment may in one or in both branches become modified, and the separate branches be thus subjected to divergent forms of endonomic selection. (10) That the indiscriminate elimination of all but a small fragment of an intergenerating group may be an important factor in introducing transformation, for one or two individuals may not be able to transmit all the traditions of the original group, or to reproduce in the innate characters of their offspring the unchanged average character of the original stock. (11) That advancing powers of accommodation, codperating with higher degrees of altruistic social organization, are in an ever-increasing measure setting aside both environal and dominational selection, and so lowering the racial standards of civilized man. A METHOD OF STUDY. 153 (12) That a perverted form of prudential selection is threatening the very existence of some nations that are counted highly civilized. _ (13) That the only remedy for these destructive tendencies lies in enlightened and renovated institutional and prudential selection, and the wide adoption of higher ideals. (14) That the most marked characteristic of modern human history is found in the breaking down of many of the minor segregations, both social and racial, of previous eras, and the ever-increasing intercourse between nations and races. (15) That, notwithstanding the general trend of the new era, among the millions of India many new castes have been established during the past century. II. CONCLUSION. 1. What has been Gained by Recognizing Habitudinal Segregation ? Having completed our study of the four principles of segregation, let us turn to the classification given in Appendices I and II, and consider what has been gained by the distinct recognition of habitudinal segregation. In Appendix I the combined action of partition and election, produc- ing segregate association of individuals according to their acquired characters, and of isolation and selection, producing segregate inter- generation of individuals according to their innate characters, is pre- sented under the single term ‘“‘ segregation.’ The action and reaction between the two spheres of segregation is not clearly presented, and, under the nomenclature there given, it would be difficult to consider all the aspects in which this interaction is manifested. In Appendix II, assimilational, stimulational, suetudinal, and emotional intension are used to designate intensification, produced by the different forms of accommodation and of acquired characters; while other terms are used to designate the intensification produced by the different forms of unbalanced propagation, securing the survival of certain types of variation in innate characters. The interaction, however, between habitudes and aptitudes is not as clearly presented in these earlier papers as in the chapters of this volume. 2. A Method of Study that should be fully Applied. I believe the facts of distribution to which I call attention are of great importance, and that the methods of collecting and of exhibiting by which these facts have been brought to light is worthy of being applied in other fields. This method may be regarded as a develop- ment of the study of ‘‘centers of creation,”’ initiated by Louis Agassiz and transformed by Darwin, Wallace, and others into the study of geographical distribution as affected by migration and divergent evo- 154 SUMMARY AND CONCLUSION. lution. In order to perfect the method it is important that the crea- tures under study should be labeled at the time of collection with the conditions (of feeding, etc.) under which each specimen was found, and should be exhibited on maps setting forth as fully as possible the conditions presented by the environment at each point. An impor- tant step in this direction has been made by the late Professor Hyatt, of the Museum of the Boston Society of Natural History, in construct- ing a model of the island of Oahu, on which the geographical relations of the species and varieties of snails from that district may be exhib- ited. It would, however, bea great gainif a model (or at least a map) of the island of sufficient size were so arranged as to allow the shells themselves to be placed upon it in their true positions, instead of being represented by letters and numbers. ‘The advantage of both methods might be attained by having, in addition to the model of the island arranged according to Professor Hyatt’s method, a very large map on which the shells might be placed. The method might be further improved by the use of colors and other devices for indicating the species of plant on which each speci- men was found. The influence of temperature, humidity, and other external conditions, and especially of the conditions interfering with free crossing, may also be studied by exhibiting the average character attained under different stages of the influence and the degree of seg- regation resulting from the full action of the combined influences. The degrees of segregation that have taken place in the inhabitants of a series of districts presenting different degrees of geographical isolation may also be studied by the determination of place-modes by statistical methods. Information on the mathematical methods that have been applied to this and other allied problems in biology will be found in the works of Francis Galton, Karl Pearson, C. B. Davenport, and others, and in ‘‘ Biometrika,’’ a journal for the statistical study of biological problems. 3. The Study of Conditions Favoring Segregation. A rich field for the study of organisms under conditions favoring segregation will be found in the fauna and flora of island groups. The most interesting conditions will appear where the majority of the species are able to distribute themselves with some degree of freedom from island to island, while some one organic form is unable to pass the water barriers, except on very rare occasions. In such a region we shall, I believe, always find a series of nearly related varieties or species distributed in the midst of a comparatively uniform environment. Simi- lar results will undoubtedly be found wherever a group of organisms AN EXAMPLE IN ACCORD WITH THE THEORY. 155 that 1s variable but of very limited powers of migration has been for many generations surrounded by a mass of spectes possessing ordinary powers of variability and ordinary facilities for distributing themselves. If this prediction is found to be in accordance with facts, it will show that the explanation of divergent evolution to which we have been led by the investigations presented in the foregoing chapters is essentially correct. 4. Prediction Confirmed by Partula of Tahitt. Since writing the preceding statement, I have read with the greatest interest Dr. A. G. Mayer’s memoir on ‘‘Some Species of Partula from Tahiti; A Study in Variation.”” The conditions of variation and migration which he brings to light in the case of some of the snails of Tahiti are a fine example of the conditions which I have found in the Hawaiian snails to be most favorable for the segregation of many closely related forms within a comparatively limited district, each section of which presents essentially the same environment. These conditions are, in the case of the closely related but divergent forms, a full degree of variability, but a very limited power of migration, and in the surrounding species the ordinary endowments in regard to variation and migration. Partula hyalina is found in all the valleys of the island of Tahiti; also on the Austral islands and on one of the Cook group. It may, therefore, have opportunities for migration that are not possessed by the other species of Partula found on Tahiti; and certainly it does not present the tendency to variation in form and color which we find in some of these species. Of these other types I will refer only to three species which are found in four valleys, in which the character of the vegetation is essen- tially the same. On the north side of the island are three approxi- mately parallel valleys, Pire, Fautaua, and Tipzrui. The first and last of these are about 3 miles apart, Pire lying on the east and Tiperui on the west, while Fautaua and several narrow gorges lie between them. ‘These three valleys are, however, ‘‘broad and well- watered, and contain a luxuriant growth of wild plantains and Cala- dium, upon which the snails are found in large numbers.’’ Besides Partula hyalina, mentioned above as found in all the valleys of the island, there are two species of Partula found in these valleys. Par- tula filosa is found only in Pir, and though constantly dextral pre- sents divers shades of color. Partula otaheitana is found in all three of the valleys, but presents hereditary tendencies differing in each of the valleys; for example, in Pire it is constantly sinistral, in Tipeerui it is constantly dextral, and in Fautaua dextral and sinistral forms are found in nearly equal numbers. 156 SUMMARY AND CONCLUSION. On the south side of the island, about 27 miles from the three valleys just mentioned, is the valley of Vaihiria, where Partula sints- trorsa isfound. Thisspecies, though closely related to the two species last mentioned, has adopted a different habit of feeding. ‘‘The Caladium and the wild plantain grow here in abundance, but most of the snails were found upon the wild turmeric, almost none being dis- covered upon the Caladium, and but few upon the leaves of the wild plantain.’”’ It is very variable in color, but easily distinguished from those of similar color in the valleys first mentioned by its lack of a tooth on the body whorl, by its relatively thin and fragile lip, by its more constricted suture, and by the lack of variation in the color of the young. Ofits individuals 90 per cent are sinistral and ro per cent dextral. From these facts Doctor Mayer draws the following conclusions: Partula hyalina is very stable in all of the valleys, and gives rise to no varieties. All the other species, however, are remarkably variable, and give rise to numerous color-sports. These color-sports tend to breed true to themselves, and, therefore, to originate new color-forms and finally new species. This tendency is, however, held in check by frequent inter-crossing with the parent stock, and becomes effective only when the new color variety is isolated, or when it displays a remark- ably strong tendency to breed true. * * * It is probable that geographical isolation plays a most important part in the formation of new species. If two valleys be adjacent, their snails are closely related each to each, whereas the wider the separation between any two valleys the more distant the relationship between their snails. The ridges between the valleys, being either barren or covered with vegetation unsuitable to the snails, afford barriers over which the animals must find it more or less difficult to pass. Thus the Partule in the Tahitian valleys are isolated very much as are the Achatinellide of Oahu in the Hawaiian Islands. * * * As far as the very limited observation of the writer goes, there appears to be no difference in the character of the snailsin different parts of the same valley. The difference between any two adjacent valleys is, however, very marked. The full statement of these facts and conclusions will be found in Memoirs of the Museum of Comparatiye Zodlogy at Harvard College, Vol. XXVI, No. 2, published in 1902. 5. The Power of the Organism to Control its Relations to the Environment Increases with the Stage of Evolution Attained. We have shown by direct observation that it frequently happens that the same species of snails, when distributed in isolated groups in districts furnishing the same environment, establishes divergent methods of dealing with the environment, and so determines the form of selection to which it is subjected in the different districts. More- over, this power of the organism to control its relations to the environment is found to belong in a higher degree to vertebrate animals, and espe- cially to birds and mammals, while immeasurably the highest power TENTATIVE VARIATION WITH HEREDITY. i) of thus shaping his relations belongs to man. Civilized man not only changes his relations to the environment, but by agriculture and other arts transforms the environment to suit his own needs. In all its -action inorganic matter is completely indifferent to the character of the results, either within the mass that is acting or in things external to it; but organic life is, throughout all its grades, striving to attain an increasing power of race preservation under given conditions, and, in its highest manifestation in man, it breaks largely away from the ancient thraldom, and assumes an ever-increasing control of the environment. 6. The Chief Method of Advance is Tentative Variation with Transmission to Offspring of the Endowments of the Survivors. Throughout this whole struggle for ascendency the principal method of advance is the sending forth of various tentative experiments in the form of variously endowed individuals presenting many methods of dealing with the environment, each individual that survives having some influence on the endowments of the next generation. This law of the survival of the fittest applies to all from the lowest to the highest; but the qualities that constitute fitness differ progressively. In one stage, strength and such weapons as teeth and claws are of the greatest importance; in another stage, the degree of intelligence and the power to produce artificial weapons is the test; and, in a still higher stage, the power of social organization and the ethical ideals that form the foundation for such organization become the supreme necessity for survival. But throughout itis the same law of survival, the survival of the fittest, the future continuance of those fitted to continue. Though plants are without conscious purpose, we neces- sarily regard their production of flowers and seed as anticipatory action; for the whole significance of the process is found in its helping to secure continued propagation. To an observer at the equator, the sun rises and sets each twenty- four hours, moving ina circle nearly perpendicular to the horizon, while to an observer at the North Pole the sun would rise and set but once in a year, and in each twenty-four hours would move through a complete circle nearly parallel to the horizon, traveling, as conven- tional language would say, from left to right; and to an observer at the South Pole, the same sun would rise and set but once in a year, and would circle in the reverse direction, that is, from right to left. Now, in such a case as this, we do not say that the cosmic process is changed. So also, in the case of ethical man, I would not say, as Hux- ley does, that his life is in opposition to the cosmic process, but rather that he has attained to one of the higher stages of that process, in which the meek are the ones who inherit the earth. 158 SUMMARY AND CONCLUSION. 7. Accommodation, Cooperation, and Antictpation. There are three spheres in which it is evident that progressive adaptation for beneficent action may take place, commencing with the smallest beginnings in the lowest organisms and progressing through each higher stage of evolution till the widest reaches are attained. These three spheres are accommodational action (whether tentative or directly discriminative), co perative action, and antictpatory action. Power for action in these spheres is characteristic of the realm of life, and is manifested in higher and higher efficiency till accommo- dation tries to prove all things, holding fast that which is good; and codperation, associated with division of labor and community of interest, reaches out to include in its beneficence the living universe ; and anticipation, pressing forward in its unbounded aspirations and ideals, becomes the ever-advancing influence of foresight and predic- tion in the activities of the highest beings. 8. Increasing Recognition of Autonomic Factors. It will be observed that throughout the whole process of evolution there are two classes of factors, of which one class may be called hete- ronomic, in that they are subject to change through change in activi- ties lying outside of the group of organisms concerned, while the other class may be called autonomic, in that they are controlled by changes within the group of organisms. In the theory of evolution presented by Darwin, the importance of the heteronomic factors was empha- sized, though he pointed out one form of autonomic transformation, which he designated by the term ‘‘sexual selection.”’ To some ex- pounders of evolution natural selection has seemed so completely sufficient that they have been ready to deny the influence of sexual selection (or of any other autonomic factor) in producing divergence. On the whole, however, there has been during the past ten or fifteen years an increasing recognition of the fact that not only sexual selec- tion but other autonomic factors are more or less effective in control- ling the forms of selection, and, therefore, in controlling the transfor- mations of organisms. Do we not thus reach one explanation of the continuous advance—the determinate evolution—of certain large classes of animals? The recognition of autonomic factors in the process of evolution is giving new insight into the self-developing endowments of the organic world, APPENDIX I. REFLEXIVE SEGREGATION.* {A small portion of ‘‘ Divergent Evolution through Cumulative Segregation.’’] T Reflexive segregation is segregation arising from the relations in which the members of one species stand to each other. It includes three classes, which I call ‘‘conjunctional,” ‘‘impregna- tional,” and ‘‘institutional segregation.”’ It is important to observe that intergeneration requires compati- bility between members of the group in all the circle of relations in which the organism stands; but, in order to insure isolation between any two or more sections of a species, it is sufficient that incompati- bility should exist at but one point. If either sexual or social instincts do not accord, if structural or dimensional characters are not correlated, if the sexual elements are not mutually potential, or if fixed institutions hold groups apart, intergeneration is obstructed or prevented and isolation is the result, either as segregation or as sepa- ration that is gradually transformed into segregation. (a) CONJUNCTIONAL SEGREGATION. Conjunctional segregation is segregation arising from the instincts by which organisms seek each other and hold together in more or less compact communities, or from the powers of growth and segmentation in connection with self-fertilization, through which similar results are gained. I distinguish four forms—social, sexual, germinal, and floral segre- gation. * Under ‘‘ Demarcational Segregation”’ I class the influences by which organ- isms are distributed in separate groups. It includes both environal segregation and reflexive segregation, and is equivalent to isolation as now generally used. In the section of this paper on Environal Segregation (not here reproduced), I considered the forms of isolation arising from the relations of the species to the environment. A classified table of the forms of segregation will be found near the end of this paper. t+ Read December 15, 1887. From the Linnean Society’s Journal, Zodlogy, Vol XX. 159 160 APPENDIX I—DIVERGENT EVOLUTION. 10. Soctal Segregation Produced by Discriminative Action of Social Instincts.* The Jaw of social instinct is preference for that which is familiar in one’s companions; and as in most cases the greatest familiarity is gained with those that are near of kin, it tends to produce breeding within the clan, which is a form of segregate breeding. If the clan never grows beyond the powers of individual recognition, or if the numbers never become so great as to impede each other in gaining sustenance, there will be but little occasion for segregation; but multiplication will lead to subdivision. Wherever the members of a species, ranging freely over a given area, divide up into separate herds, flocks, or swarms, of which the members produced in any one group breed with each other more than with others, there we have social segregation. It should always be kept in mind that social segregation arises at a very early stage, often holding apart groups but very slightly differ- entiated; while in the case of many animals the sexual instincts of the males tend to break up these minor groups. Though the barriers raised by social instincts are often broken over, their in- fluence is not wholly overcome, and in many instances the social segregation becomes more and more pronounced, till in time decided sexual segregation comes in to secure and strengthen the divergence. 11. Sexual Segregation is Produced by the Discriminative Action of Sexual Instincts. There can be no doubt that sexual instincts often differ in such a way as to produce segregation. But how shall we account for these differences? In the case of social segregation there is no difficulty, for it seems to be, like migration, due to a constant instinct, always tending to segregation. We also see that an endowment which pre- vents the destruction of the species through the complete isolation of individuals, and which codperates with migrational instincts in secur- ing dispersal without extinction, may be perfected by the accumulat- ing effects of its own action. And is there any greater difficulty in accounting for the law that regulates sexual instincts? If it can be shown that vigor and variation, the conditions on which adaptation depends, are in their turn dependent on some degree of crossing, there will be no difficulty in attributing the development of an instinct that secures the crossing to the selection of the individuals that possess it in even a small degree. On the other hand, whenever there arises a variety that can maintain itself by crossing within the same * Numerals are used to designate causes of segregation not depending on human purpose. Of these nine were mentioned in the section on environal segregation. SEXUAL SEGREGATION. 161 variety, any variation of instinct that tends to segregation will be preserved by the segregation. It needs no experiments to prove that _if the members of a species are impelled to consort only with the mem- bers of other species, they will either fail to leave offspring or their offspring will fail to inherit the characteristics of the species. The same is true concerning the continuance of a variety that is not some- how segregated. The power of variation on the one hand, and the power of divergent accumulation of variations on the other hand, are prime necessities for creatures that are wresting a living from a vast and complex environment; and the former is secured by the advan- tage over rivals possessed by the variations that favor crossing, and the latter by the better escape from the swamping effect, and some- times from the competition of certain rivals, secured by the more segregative variations. We must, therefore, believe that whenever in the history of an organism there arise segregative variations which are able to secure sufficient sustentation and propagation to continue the species, the segregative quality of the forms thus endowed will be preserved and accumulated through the self-accumulated effect of the segregative endowments. It is probable that in many of the higher vertebrates sexual in- stincts tend to bring together those of somewhat divergent character, but the difference preferred is within very narrow limits; and beyond those limits it may be said that the general law for sexual attraction is that it varies inversely as the difference in the characters of the races represented, if not inversely as some power of such difference. The action of such a law is necessarily segregative whenever the diver- gence has, through other causes, passed beyond the limit of higher attraction. Before sexual segregation can arise, there must arise distinctive characteristics by means of which the members of any section may discriminate between those of their own and other sections. If there are no constant characteristics there can be no constant aversion between members of different groups, no constant preference of those of one’s own group. From this it follows that before sexual segregation can arise, some form of segregation that is not dependent on distinct characteristics must have produced the divergence on which the sexual segregation depends. Such forms are local, social, and some kinds of industrial segregation. When varieties have arisen through these causes it often happens that sexual segregation comes in and perpetuates the segregation which the initial causes can no longer sustain. As long as the groups are held apart by divergent sexual instincts, it is evident that divergent forms of sexual selection are almost sure to arise, leading to a further ac- cumulation of the divergence initiated by the previous causes. 162 APPENDIX I—DIVERGENT EVOLUTION. If there is any persistent cause by which local and social groups are broken up and promiscuously intermingled before recognizable char- acters are gained, the entrance of sexual segregation will be prevented. I therefore conclude that the chief influence of this latter factor is found in its prolonging and fortifying the separate breeding of varie- ties that have arisen under local, social, or industrial segregation, and in thus continuing the necessary condition for the development of increasingly divergent forms of intensive segregation, under which the organism passes by the laws of its own vital activity when dealing with a complex environment in groups that never cross. 12. Germinal Segregation is Caused by the Propagation of the Species by means of Seeds or Germs, any one of which, when developed, forms a community so related that the members breed with each other more frequently than with the members of other communities. If the constitution of any species is such that the ovules produced from one seed are more likely to be reached and fertilized by pollen produced from the same seed than by pollen produced from any other one seed, then germinal segregation is the result. In order to secure this kind of segregation it is not necessary that the flowers fertilized by pollen from the same plant should be more fertile or the seeds capable of producing more vigorous plants than the flowers fertilized by pollen from another plant. All that is re- quired is that the seeds produced by each individual plant shall be fertilized by the pollen of the same plant. This form of segregation is closely related to local segregation on one side and to social segregation ontheother. It, however, differs from the former in that it does not depend on migration or trans- portation, and from the latter in that it does not depend on social instincts. 13. Floral Segregation is Segregation arising from the Closest Form of Self-fertiliza- tion, namely, of the Ovules of a Flower by Pollen from the same Flower. Some plants that in their native haunts are frequently crossed by the visits of insects depend entirely on self-fertilization when trans- ported to other countries where no insect is found to perform the same service for them. The common pea (Pisum sativum) is an example of a species that does not fail of propagating in England, though Dar- win found that it was very rarely visited by insects that were capable of carrying the pollen, and the pollen is not carried by the wind.* Darwin also mentions Ophrys apzfera as an orchid which ‘“‘has almost certainly been propagated in a state of nature for thousands of gen- erations without having been once intercrossed.’’ * Cross and Self Fertilization in the Vegetable Kingdom, p. 161. ~—¢ Jbid., p. 439 IMPREGNATIONAL SEGREGATION. 163 GENERAL OBSERVATIONS ON GERMINAL AND FLORAL SEGREGATION. A fact of great importance in its bearing on the origin of varieties _ should be here noted. Any variation, arising as a so-called sport, in any group of plants where either of these principles is acting strongly, will be restrained from crossing, and will be preserved except in so far as reversion takes place. Now, there isalwaysa possibility that some of the segregating branches of descent will not revert, and that, through the special character which they possess in common, they will some time secure the services of some insect that will give them the benefit of cross-fertilization with each other without crossing with other varieties. The power of attaining new adaptations may be favored by self-fertilization occasionally interrupted by interbreeding with individuals of another stock; for the latter is favorable as intro- ducing vigor and variation, and the former as giving opportunity for the accumulation of variations. These two methods of propagation are so far removed from those found in the majority of species that it may be wise to consider any transformation arising under such conditions as belonging to a separate department of the process of evolution. Organisms that are self-fertilized in all their generations seem to stand in nearer relation to species entirely without the power of sexual propagation than to species in which cross-fertilization is the usual method of propagation. (b) IMPREGNATIONAL SEGREGATION. Impregnational segregationis due to the different relations in which the descendants of one original stock stand to each other in regard to the possibility of their producing fertile, vigorous, and fully adapted offspring when they consort together. In order that impregnational segregation should be established and perpetuated, it is necessary, first, that variation should arise, from which it results that those of one kind are capable of producing vig- orous, adapted, and fertile offspring in greater numbers when breeding with each other than when breeding with other kinds; second, that mutually compatible forms should beso brought together as to insure propagation through a series of generations. In order to secure this second condition, it is necessary that, in the case of plants, there should be some degree of local, germinal, or floral segregation, and, in the case of animals that pair, either pronounced local segregation or partial local segregation, supplemented by social or sexual segregation. The action of the different forms of impregnational segregation I call negative segregation, for they rest on incompatibilities interfering with mixed unions or allowing of no offspring, or of but few or inferior offspring, as the result of mixed unions, and, unaided by positive seg- 164 APPENDIX I—DIVERGENT EVOLUTION. regation, can do nothing toward bringing creatures together accord- ing to their compatibilities. The forms of segregation that place or draw together creatures of like innate characters I call forms of post- tive segregation. Of each form of segregation which we have up to this point con- sidered, the segregating cause has been one that distributes individuals of the same species in groups between which free intergeneration is checked; while the propagation of the different groups depends sim- ply on the original capacity for intergenerating common to all the members of the species. The intercrossing has been limited not by the capacity but by the opportunity and inclination of the members. Coming now to cases in which complete lack of capacity for fruitful crossing is the cause that prevents the production of mongrels, we find a dependence of a very different kind; for to insure the propagation of the different groups it is not enough that the general opportunity for the members of the species to meet and consort remains unimpaired. There must be some additional segregating influence bringing the members together in groups corresponding to their segregate capacity, or they will fail of being propagated. The form of impregnational segregation which I call prepotential segregation is due to the prepotency of the pollen of a species or variety on the stigma of the same species or variety, and complete potential segregation is due to the potency of the pollen of the same species, with the complete impotence of the foreign pollen. When allied species of plants are promiscuously distributed over the same districts, and flowering at the same time, prepotency of this kind, aided by the free dis- tribution of the pollen by the wind, is one of the most direct and efficient causes of segregate breeding. The same must be true of varieties similarly distributed whenever this character begins to affect them. In the case, however, of dicecious plants and of plants whose ovules are incapable of being impregnated by pollen from the same plant, no single plant can propagate the species. If, therefore, the individuals so varying as to be prepotent with each other are very few, and are evenly distributed amongst a vast number of the original form, the probability is that they will fail of being segregated through failing to receive any of the prepotent pollen. Itis thus apparent that when the mutually prepotent form is represented by comparatively few indi- viduals, their propagation without crossing will depend on their being self-fertile and subject to germinal or floral segregation, or on their being brought together by some other form of positive segregation. When a considerable number of species of plants are commingled and are flowering at the same time, their separate propagation is DIMENSIONAL AND STRUCTURAL SEGREGATION. 165 preserved, in no small degree, by the prepotential segregation of those that are most nearly allied and by the complete potential segregation _of those that belong to different families, orders, and classes. The same principle must come in to prevent the crossing of different spe- cies, genera, families, and orders of animals whose fertilizing elements are distributed in the water. When aided by this free distribution the combined effect is that of positive as well as negative segregation; for the free distribution of the fertilizing element, with the superior affinity of the two sexual elements that are mutually prepotent, secures the interbreeding of the species or variety producing the mutually prepo- tent elements. | Impregnational segregation generally exists between the different species of the same genus, almost always between species of different genera, and always between species of different families, orders, classes, and all groups of higher grade. And in all these cases it is associated with other forms of segregation, and when once complete the groups affected never coalesce. Though complete mutual ster- ility never gives place to complete mutual fertility, in every case where the descendants of the same stock have developed into different classes or orders, and in most cases where they have developed into different families or genera, the reverse process has taken place, and complete mutual fertility has given place to complete mutual sterility. Under impregnational segregation I distinguish dimensional segre- gation, structural segregation, potential segregation, segregate fecun- dity, segregate vigor, segregate adaptation, segregate freedom from competition, and segregate escape from enemies. 14, Dimensional Segregation (or Segregative Size) is caused by Incompatibility in Size or Dimensions of the Individuals of the Different Breeds. As familiar illustrations of this form of segregation, I may mention the following: The largest and smallest varieties of the ass may run in the same pasture without any chance of crossing. I have also kept Japanese bantam fowls in the same yard with other breeds without any crossing. In many other species individuals of extreme diver- gence in size are incapable of interbreeding. 15. Structural Segregation (or Segregative Structure) 1s Caused by Lack of Correlation in the Size of Different Organs and by other Incompatibilities of Structure. Darwin suggests that the impossibility of a cross between certain species may be due to a lack of correspondence in length of the pollen tubes and pistils. Such a lack of harmony would perhaps account for difference of fertility in reciprocal crosses, according as the male is of the one variety or of the other. 166 APPENDIX I—DIVERGENT EVOLUTION. Segregative structure does not usually arise till other forms of segre- gation have become so well established that difference of structure does not make any essential difference in the amount of intergenera- tion. It is not, however, impossible that species that would otherwise freely cross are thus held apart. In Broca’s work on ‘‘Human Hybridity’’* there is a passage quoted from Prof. Serres showing that it is very possible that this form of incompatibility may exist between certain races of men. 16. Potential Segregation (or Segregative Potency) in its Two Forms, Complete Potential Segregation and Prepotential Segregation. (1) Nature of the Principle.—It is caused by the greater rapidity and efficiency with which the sexual elements of the same species, race, or individual combine. Complete potential segregation is caused by the mutual impotence of the contrasted forms, as is always the case between different orders and classes; and prepotential segre- gation is caused by the superior influence of the fertilizing element from the same species, race, or individual, as contrasted with that from any other species, race, or individual, when both reach the same ovum at the same time, or sometimes when the prepotent element comes many hours after the other. That propagation may result compatible elements must meet. When pollen from a contrasted genus, order, or class has no more effect than inorganic dust, it seems appropriate that we should call the result complete potential segregation rather than prepotential segregation, which implies that the foreign as well as the home pollen is capable of producing impregnation. Prepotential segregation may be considered the initial form of potential segregation. The principle is fundamentally one, though it will be convenient to retain both names. The importance of this principle in producing and preserving the diversities of the vegetable kingdom can hardly be overstated. If pollen of every kind were equally potent on every stigma, what would the result be? What distinctions would remain? And if potential segregation is necessary for the preservation of distinctions, is it not equally necessary for their production? Amongst water animals that do not pair, the same principle of segregation is probably of equal importance. Concerning this form of segregation many questions of great interest suggest themselves, answers to which are not found in any investigations with which I am acquainted. * English translation, published by the Anthropological Society of London, p. 28. POTENTIAL SEGREGATION. 167 Some of these questions are as follows: (2) Points needing investigation.—First. Are there many cases of prepotential as well as of complete potential segregation between dif- ‘ferent forms of water animals? Second. Is prepotential segregation always accompanied by segre- gate fecundity and segregate vigor? Third. If not always associated, which of the three principles first appears? And what are their relations to each other? Fourth. When allied organisms are separated by complete environal segregation, are they less liable to be separated by these three prin- ciples? Darwin has in several places referred to the influence of prepotency in pollen, and in two places I have found reference to the form of pre- potency that produces segregation; but I find no intimation that he regarded this or any other form of segregation as a cause of divergent evolution. The effect of prepotency in pollen from another plant in preventing self-fertilization is considered in the tenth chapter of his work on ‘‘Cross- and Self-fertilization in the Vegetable Kingdom,”’ pp. 391-400. Some very remarkable observations concerning the pre- potency of pollen from another variety than that in which the stigma grows are recorded in the same chapter, but no reference is there made to the effect that must be produced when the pollen of each variety is prepotent on the stigma of the same variety. In Chapter XVI of ‘‘ Variation under Domestication ”’ it is suggested that prepotency of this kind might be a cause of different varieties of double hollyhocks reproducing themselves truly when growing in one bed, though there was another cause to which the freedom from crossing in this case has been attributed. Again, in Chapter VIII of the fifth edition of ‘‘The Origin of Species,” in the section on ‘‘’The Origin and Causes of Sterility,’ Darwin, while maintaining that the mutual sterility of species is not due to natural selection, refers to prepotency of the kind we are now considering as a quality which, occurring in ever so slighta degree, would prevent deterioration of character, and which would, therefore, be an advantage to a species in the process of formation, and accordingly subject to accumulation through natural selection. In order to construct a possible theory for the introduction of sterility between allied species by means of natural selection, he finds it necessary simply to add the supposition that sterility is directly caused by this prepotency. He, however, for several reasons, concludes that there is no such dependence of mutual sterility on the process of natural selection. Concerning the pre- potency he makes no reservation, and I accordingly judge that he 168 APPENDIX I—DIVERGENT EVOLUTION. continued to regard it as strengthened and developed through the action of natural selection.* (3) Reasons for believing that potential segregation can not be accu- mulated by natural selection.—Concerning this last point I wish to give reasons fora different opinion. I believe that qualities simply produc- ing segregation can never be accumulated by natural selection, for— First. When separate generation comes in between two sections of a species they cease to be one aggregate, subject to modification through the elimination of certain parts. Both will be subject to sim- ilar forms of natural selection only so long as the circumstances of both and the variations of both are nearly the same, but they will no longer be the members of one body between which the selecting pro- cess is carried out. On the contrary, if they occupy the same district each group will stand in the relation of environment to the other, mod- ifying it, and being modified by it, without mutually sharing in the same modification. Second. Though one may exterminate the other, the change that comes to the successful group through the contest is not due to its superiority over the other, but to the superiority of some of its own members over others. Third. Whenany segregate form begins toarise we can not attribute its success to the advantage of isolation, for it is not the success, but the separateness of the success, that is due to the isolation. Fourth. The power of migration, or any other power directly re- lated to the environment, may be accumulated by natural selection, and afterward lead to segregation, but, according to my method of judging, the advantage of segregation over intergeneration is not the cause of the preservation of forms endowed with segregative qualities, for they will certainly be preserved as long as they are able to wina bare existence, which is often a lower grade of success than the one from which they are passing. (4) How shall we explain the accumulation of potential segregation2— But if the accumulation of prepotential segregation is not due to nat- ural selection, how shall we explain it? The divergence of a group can not take place without its being segregated from the original stock as well as from other types; and the potency of the sexual elements of the new group will be maintained in their relations to each other by some form of reflexive selection; butas there can be no reflexive selec- tion between the segregated groups, the potency of the elements for crossing outside of the group will in time be impaired; and then we * Since my comments on this passage were written I have discovered that Dar win has omitted it from the sixth edition. ACCUMULATION OF POTENTIAL SEGREGATION. 169 shall have prepotency of each group within the circle of its own group. This process may take place when a group is protected by complete isolation, however produced. Let us next consider a case in which a ‘small group partially protected from mixture with the original type by incomplete local and industrial segregation produces a variation whose ovules are more readily fertilized by pollen from the same group than by pollen from the original type. Is it not evident that this variation will gain with each generation an increasing prominence in the new group that maintains somewhat new methods of dealing with the environment in its partially isolated habitat? This will be so, first, because variations possessing but little or no prepotency with their own group will eventually coalesce with the original stock, and especially will this be the case if the new group becomes somewhat numerous and passes beyond the limits of its narrow habitat into districts where the original type abounds; and, second, because vari- ations possessing the prepotency with their own group in a superior degree will remain distinct, breeding with each other, and their de- scendants will become still more segregate and still more perma- nently divergent. Of the law of accumulation of segregative endow- ments, we may say that as the descendants of the best fitted necessarily generate with each other and produce those stull better fitted, so the de- scendants of those possessing the most segregative endowments necessarily generate with each other and produce those that are still more segregate. It will, however, soon be shown that unless the reproduction and power of survival is greater for the pure segregate forms than for the mixed forms, the proportion of pure forms to mixed forms will decrease in each generation. It is evident that when either segregate potency or segregate pre- potency is associated with the free distribution of the fertilizing ele- ment by wind or water, the combined effect must be in the former case complete, and in the latter case partial, positive segregation, for the breeding together of compatible forms is thereby secured. It may at first appear that a slight degree of segregate prepotence will prevent crossing as effectually as a higher degree, but further reflection will show that the efficiency of the prevention will vary in direct proportion with the length of time over which the prepotent pollen is able to show its prepotence, and this will allow of innumer- able grades. If, in the case of certain individuals, the prepotency is measured by about twenty minutes, while with other individuals it enables the pollen of the same variety to prevail though reaching the stigma an hour after the pollen of another variety has been applied, the difference in the degree of segregation will be sufficient to make the persistence of the latter much more probable than that of the 170 APPENDIX I—DIVERGENT EVOLUTION. former. This form of segregation is evidently one of the important causes preventing the free crossing of different species of plants. It probably has but little influence on terrestrial animals; but how far it is the cause of segregation among aquatic animals is a question of no small interest, concerning which I have but small means for judging. I have, however, no hesitation in predicting that, unless we make the presence of this segregative quality the occasion for insisting that the forms so affected belong to different species, we shall find that amongst plants the varieties of the same species are often more or less separated from each other in this way. Ido not know of any experiments that have been directed toward the determining of this point; but on the general principle that race distinctions are the initial forms under which specific differences present themselves, I can have no doubt that feeble prepotence precedes that which is more pronounced, and that part of this divergence in many cases takes place, while the diver- gent branches may be properly classed as varieties. Another reason for believing that prepotential segregation will be found on further investigation to existin some cases between varieties is the constancy with which, in the case of species, this character is associated with segregate fecundity and segregate vigor, which we know are sometimes characteristics of varieties in their relation to each other. 17,18. Segregate Fecundity and Segregate Vigor. By segregate fecundity I mean neither segregation produced by fecundity nor fecundity produced by segregation, but the relation in which species or varieties stand to each other when intergeneration of members of the same species or variety results in higher fertility than the crossing of different species or varieties. In like manner segregate vigor is the relation in which species or varieties stand to each other when the intergeneration of members of the same species or variety produces offspring more vigorous than those produced by crossing with other species or varieties. Integrate fecundity and integrate vigor are the terms by which I indicate the relation to each other of forms in which the highest fertility and vigor are produced by crossing, and not by independent generation. 19. Segregate Adaptation.* Segregate adaptation is the relation in which species or varieties stand to each other when the intergeneration of individuals of the same species or variety produces offspring better adapted than the * This and the following paragraph were not in the paper as first published, though the advantage of escape from severe competition with members of the same species was set forth in the paragraph entitled ‘‘ Competitive disruption.” SEGREGATE FECUNDITY, VIGOR, AND ADAPTATION. Le 7 fa offspring produced by crossing with other species or varieties. Nat- ural selection is the survival of the best adapted of the variations that remain and breed with the stock under consideration, but it takes no eognizance of the fitness or lack of fitness of individuals or a race that separate themselves from the intergenerating mass. The different grades of fitness for their new life found among the individuals that form the new intergenerating group will be the ground for divergent natural selection in the new group; but they will not affect the type of the original stock. Now, whenever the conditions and aptitudes of the two groups are so different that the offspring of cross-unions are less fitted for life under either set of conditions than is either group of the pure-breeds for its own peculiar life, we shall have a new principle, different in its effects from natural selection. This I call segregate adaptation. Natural selection is the survival of the fittest that inter- generate; segregate adaptation is the superior fitness and survival of the offspring produced by segregate generation. 20, 21. Segregate Freedom from Competition and Segregate Escape from Enemies. Segregative endowments may be necessary to the enjoyment of cer- tain advantages which are gained not by superior adaptation to the environment, but by endowments that set them in a position where competitors and enemies are as yet few. These two principles I have called segregate freedom from competition and segregate escape from enemies. Segregate freedom from competition or segregate access to unused resources results when the pure offspring have freer access to unused resources than do the cross-breeds or the original stock. Segregate escape from enemies (an advantage often of equal import- ance with that just mentioned) arises whenever the pure offspring of a divergent variety are able to occupy a position freer from enemies than that occupied by the original stock. (c) INSTITUTIONAL SEGREGATION. Institutional segregation is the reflexive form of rational segrega- tion. It is produced by the rational purposes of man embodied in institutions that prevent free intergeneration between the different parts of the same race. As the principal object of the present paper is to call attention to the causes of segregation acting independently of effort and contriv- ance directed by man to that end, it will be sufficient to enumerate some of the more prominent forms under which institutional segrega- tion presents itself, noting that some of these influences come in as 172 APPENDIX I—DIVERGENT EVOLUTION. supplemental to the laws of segregation already discussed, simply reinforcing by artificiai barriers the segregations that have their orig- inal basis in nature. ‘The chief forms to be enumerated are national, linguistic, caste, penal, sanitary, and educational segregation.* CONCLUDING REMARKS. 1. Impregnational Segregation a Cause of Divergence in both its Earlier and Later Stages. The negative forms of segregation would tend to produce extinc- tion if they were not associated with the positive forms of segregation. But in the case of organisms whose fertilizing elements are dis- tributed by wind and water, the qualities that produce these nega- tive forms of segregation are usually accompanied by those that produce potential segregation, and potential segregation coéperating with this free distribution results in positive segregation. But even prepotential segregation, when produced by mutual incompatibility between a few individuals and a numerous parent stock, depends for its continuance and development on some degree of local, germinal, or floral segregation, partially securing the intergeneration of the few that are mutually compatible. On the one hand, impregnational segregation depends on some degree of local, germinal, or floral segre- gation which is a constant feature in most species; and, on the other hand, not only do these initial forms of positive segregation fail of producing any permanent divergence till associated with impreg- national segregation, but the more effective forms of positive segrega- tion, such as industrial, chronal, fertilizational, sexual, and social segregation, often depend on impregnational segregation, inasmuch as the divergence of endowments which produces these depends on impregnational segregation. Moreover, in all such cases, increasing degrees of diversity in the forms of adaptation, and consequently of diversity in the forms of natural selection, must also depend upon these negative factors, which in their turn depend on the weak, initial forms of positive segregation. Divergent evolution always depends on some degree of positive segregation, but not always on negative segregation. Under positive * This completes the classification of the forms of isolation which are here pre- sented as forms of demarcational segregation. It is probably correct to say that with the exception of transportational and geological isolation, and perhaps some cases of migrational isolation, all the forms of isolation so far discovered are, from the first, more or less discriminative, and, therefore, segregative. Moreover, if transportational or geological action plants an isolated colony of only a few indi- viduals, the average type of the original stock is not fully represented in the colony and, therefore, the effect is more or less segregative from the beginning. SEXUAL INCOMPATIBILITY. 173 segregation of a rigorous form (as, for example, complete geograph- ical segregation), considerable divergence may result without any sexual incompatibility. Darwin has shown, by careful experiments, ‘that integrate vigor and fecundity is the relation in which the varieties of one species often stand to each other. This fact does not, how- ever, prove that the more strongly divergent forms, called species, which are prevented from coalescing by segregate vigor and fecundity, did not acquire some degree of this latter character before any perma- nent divergence of form was acquired. Their having acquired this segregating characteristic may be the very reason why their forms are now so decidedly different, for without it they would have been swal- lowed up by the incoming waves of intergeneration. Again, we must remember that forms only moderately divergent are habitually classed as different species if they are separated by segregate vigor and fecundity (that is, by some degree of mutual sterility), unless observation shows that they are of common descent. These two considerations sufficiently explain why the varieties of one species are so seldom reported as mutually infertile. Notwithstanding this, the experiments of Gartner and of Darwin seem to show that seg- regate fecundity and vigor may arise between varieties that spring from one stock. In view of these cases we must believe that in the formation of some, if not many species, the decisive event with which permanent divergence of allied forms commences is the intervention of segregate fecundity or vigor between these forms. Positive segregation, in the form of local, germinal, or floral segrega- tion, producing only transitory divergences, always exists between the portions of a species that has many members; but as it does not directly produce the negative segregation which is, in such cases, the necessary antecedent of permanent divergence, we can not, in accord- ance with the usage of language, call it the cause of the permanent divergence. Moreover, though it may be in accordance with ordinary language to call the negative segregation, which is the immediate antecedent of the permanent divergence the cause of the same, it will be more correct to call the coincidence of the negative and positive segregations the cause, and still more accurate to say that the whole range of vital activities (when subjected to the limitations of any sexual incompatibility that corresponds in the groups it separates to some previous but ineffectual local, germinal, or floral segregation) will produce permanent divergence. In many cases not only is the entrance of impregnational segrega- tion the cause of the commencement of permanent divergence, but its continuance is the cause of the continuance of the divergence. The 174 APPENDIX I—DIVERGENT EVOLUTION. clearest illustration of this is found in the case of plants that are fer- tilized by pollen that is distributed by the wind. All the higher, as well as the lower, groups of such plants would rapidly coalesce if each grain of pollen was capable of producing fertilization, with equal cer- tainty, promptness, and efficiency, on whatever stigma it might fall. We may also be sure that with organisms that depend upon water for the distribution of their fertilizing elements, impregnational segrega- tion is an essential factor in the development of higher as well as of lower taxonomic groups. It is important to observe that, in the cases under consideration, the inferior fertility or vigor resulting from the crossing of the incom- patible forms is as truly a cause of divergence as the injerior oppor- tunity for crossing which from the first existed between the members occupying different localities or between flowers growing on different trees of the same species. ‘The former has been called negative and the latter positive segregation, not for the sake of distinguishing different grades of efficiency, but for the sake of indicating the different methods of operation in the two classes of segregation. 2. Isolation Usually Somewhat Discriminate, and therefore Segregative, from the Furst. Of the twenty-one natural forms of isolation enumerated in this paper, there are only two that are usually indiscriminate in their action. These are transportational segregation and geological segre- gation. And even these sometimes become discriminate in their action through the fact that those individuals that are similarly endowed are liable to be transported in the same way and to the same place, or to escape together from destruction in geological disturb- ances. Again, it may happen that by gradual subsidence a large island will be divided into two smaller islands, and thus certain species inhabiting the original island may be indiscriminately isolated. But even in such a case, unless the average inheritable character of each section of the species is exactly the same in all respects, the effect is segregative from the first. If one, or both, of the sections is very small, the probability of exact similarity in all respects entirely dis- appears, unless the species is wanting in plasticity and variability. 3. Principles Intensifying Segregation. Besides artificial and institutional segregation, which depend on the rational purpose of man, we have now considered 21 forms of seg- regation, resting on purely natural causes. At some other time I shall endeavor to present the natural laws that coéperate in intensifying the effects produced by the segregative PRINCIPLES INTENSIFYING SEGREGATION. 175 causes already considered. Segregation is not simply the indepen- dent generation of different sections of a species, but the independent generation of sections that differ. Though indiscriminate isolation of ‘a small section of a species may produce an initial difference, it is evident that the degrees of difference may be greater or less, and that whatever causes a greater difference in two sections that are prevented from intergenerating will also be a cause of increased segregation, and may be classed as a form of intensive segregation. It has been observed that some of the causes enumerated in this chapter are primarily separative, and that no one of those that are primarily segregative is at any one time segregative in regard to many classes of characters. As several forms of segregation may codperate in securing a given division of a species, and one form is superimposed upon another, the aggregate effect must be great; but we easily perceive that it may be indefinitely enhanced by causes producing ‘ increased divergence in the segregated branches. ‘The causes which produce monotypic evolution when associated with intergeneration must be equally effective in producing polytypic evolution when asso- ciated with isolation whether in its separative or segregative forms. But the discussion of intensive segregation must be reserved for another occasion. A Lack in this First Classtfication of Segregative Principles.* The classification’ of segregative principles here given does not draw any clear distinction between those resting upon acquired characters and habitudes and those resting upon innate characters and aptitudes. For example, industrial segregation is defined as “‘Segregation arising from the activities by which the organism protects itself against adverse influences in the environment, or by which it finds and appropriates special resources in the environment.” Now it is manifest that in some cases the different methods of using the environment may be determined by acquired habitudes rather than by inherited aptitudes, and the demarcation thus produced will, in the first place, be habitudinal, though in the end it may result in racial demarcation. The interaction between the principles producing racial segregation and those producing habitudinal segregation is discussed in Chapter V (pp. 45-78). It should also be noted that since this paper was brought before the Linnean Society, isolation has come into general use for designating the prevention of free crossing, by which the demarcation of racial groups is determined. This leaves the term ‘‘segregation”’ more free to designate the combined action of the prin- ciples producing the demarcation of groups and of those producing the intensifi- cation of the characters of the separated groups. Partition and isolation pro- ‘duce habitudinal and racial demarcation, while election and selection produce habitudinal:and racial intensification, and the combined action of the four principles produces segregation both racial and habitudinal. (For a fuller state- ment see Chapters V and VI.) “As this explanation does not occur in the original paper it is printed in different form. 176 APPENDIX I—DIVERGENT EVOLUTION. 4. Classified Table of Forms of Segregation.* DEMARCATIONAL SEGREGATION [OR ISOLATION]. A. Environal segregation: (a) Industrial segregation. Suistentationalarvar © cca cicic oreratera suet rehome enero eel creek teicher oaaiciere I DD ELENSIV.E siti aise oh cone clean ics rertotrrerererieratnene er snatatete tate 2 Niditieationallessmier: cir ceiee ts cite eleret ner ivenetetciekete rotten (b) Chronal segregation. Cyclical ips bivesiys cystitis. hie Bats ohd tet else bene laredetont Ente octet tea enenete 4 Seasotiallls oxy ctecig tic ce aes risen e bac asl erae abet ent tekeh here pemare 5 (c) Spatial segregation. Geographical (Migrational HyTe SAAS atic mabe petra Cs mioeenena rete 6 Renan spOLtationalla. qalaaeleier eet oe eaten 7 Local : (Geological Iie isda lune ble de takerd Schaerer oe eee 8 (d) Fertilizational segregation iro aca -/ce on ola wee one ic eevee tee 9 (e) Artificial segregation. B. Reflexive segregation: (a) Conjunctional segregation: yor El Wie ORR) PERIENCE eter MPEG UP ERC IN iD EN ey Resist Ane 10 ese eta yh ck Sociale hace BURR ohio rake Sy She Ra he GRRE a Phere oer II Gravina | ite sass) otekegevtn ce vile ales perere ls assess asic site eee ea ee 12 Bokorath yo 2 ye ay aM Le air eee ae 13 (6) Impregnational segregation: Segrevativie Size. Jacie'smievsls sete tals Stele A uetaiay oi eyerle Leeda teal renee eee 14 Seerecative Stricture, oj isj cits ge yene a eras taol a ciel tae eee ea 15 Potentialisesregationy...da sock ss samen else te neciekcre dete 16 Segregate fecundity {a0 ous vans circle eae eine) tence eet 17 SECKegate VigOt cree pt eeiois = 2 \chalvo tt ote aloe eee ee aie eae 18 Sevregate adaptation... /(<\:15 2 sare estrella +) eae ell ie] aye eee 19 Segregate freedom from competition ...................... 20 Sepregate escape froin enemies 6.65. 652i wae asics sole ueee 21 (c) Institutional segregation. INTENSIVE SEGREGATION. (a) Assimilational intension. (e) Amalgamational intension. (6) Stimulational intension. (f) Selectional intension. (c) Suetudinal intension. (g) Fecundal intension. (d) Emotional intension. (hk) Eliminational intension. * Numerals are attached to the forms of segregation found in natural species. COMPUTATIONS OF EFFECTS. 177 5. Computation of the Effects of Different Degrees of Positive Segregation Cooperating with Different Degrees of Segregate Survival. * Of the tables which are herewith presented Table I is an arithmet- ical computation, showing the number of half-breeds as contrasted with the pure-breeds, when nine-tenths of each variety form unions among themselves and double with each generation, while the off- spring of the one-tenth that form mixed unions simply equal the number of the parents by which they are produced; in other words when c = 0.1, M = 2, m = 1 (see Table II). TABLE I. Three- . . Of what gener- | Half of the |abastes Variety No. 2, ERIE SS DT oto ation. half-breeds. | pe Bre Dress! | side. + | 1:3 oe ee ee eee Initial number Ne Peta 1, 000 1.8 | | | res OOm—— PAG (eS) easieriensn ete Ist generation. TOO) ee ssace il 1, 800 1.8 | | ue oe: l(a) ee 2d generation. 260 | 20 3, 240 1.8 | eS aire IAG (TS) ced) eu d 3d generation. 532 72 Cee 357.05 = (1.8)!9° comput- | ed by log. .°.357,050 = PAG (ES) eds tae res sci ageha ae roth generation 35, 688 | 357, 050 39,347-272 = (1.8)*® .”.39,347,272 = A(1.8)!*.| 18th generation|3, 934, 725 | 20, 347), 272 } EXPLANATION OF TABLE I. The 2d generation of the half-breeds is found by taking nine-tenths of the pre- vious half-breeds, 7. e., 100 X 0.9 = 90, and one-tenth of the previous pure-breeds (the one-tenth that form mixed unions), minus one-tenth of the previous half- breeds (because one-tenth of the half-breeds consort with an equal number of pure-breeds, and so produce not half-breeds but three-quarter breeds), 7. ¢., 180 — 10 = 170. Adding these two sums together we have 90 + 170 = 260 = the 2d generation of half-breeds. As in this table the computation commences without any half-breeds, the fol- lowing generations of half-breeds are all a little less than one-tenth as large as the corresponding generations of pure-breeds. When, however, we come to the 18th generation the difference is less than one in a million, and we may consider the result as practically corresponding with the formula for the nth generation given in Table III. 178 APPENDIX I—DIVERGENT EVOLUTION. Table II is a preliminary formula for showing the proportion of half-breeds to pure-breeds. Let R = 1 —c = the ratio of pure breeding, 7. ¢., the segregation. Let c = the ratio of cross-breeding, 7. e., the segregation viewed from the other side. Ex.—When nine-tenths of the unions are within the limits of the species and one- tenth of the unions are with an allied species R = 0.9, c =0.1. R will always equal 1 —c. Let / = the ratio of fertility in each generation for those that breed with their own kind. Let m = the ratio of fertility in each generation for the cross-unions and for the hybrids when breeding together. Let A = the initial number of individuals representing the pure species when the computation commences. TABLE II. Number of individuals representing | the pure form. Number of individuals representing the half-breeds. A = Initial number. | A(RM) = Ist generation. | Ist generation = Acm. A(RM)? = 2d generation. | 2d generation = (AcmR + A(RM)c — Acmc) X m. A(RM)* = 3d generation. | 2d generation = (AcmR — Acmc)m + Acm(RM). A(RM)* = 4th generation. | 2d generation = Acm(R—c)m+ Acm(RM). Substituting (1 — c) for R in the 2d ! Substituting in this (1 —c) for R, we have generation, we have A(M — | 24 generation = Acm(1 — 2c)m + Acm(M — Mc). | Mc)2 = 2d generation. | EXPLANATION OF TABLE II. The term AcmR represents the number of half-breeds that form unions among themselves, the offspring being half-breeds; A(M)c represents the total number of pure-breeds of the 1st generation that form mixed unions; of these Acmc form unions with an equal number of half-breeds, and their offspring being three- quarter breeds must be rejected; the remainder, namely, A(RM)c — Acme, form unions with the other race, and their offspring are half-breeds of the 2d generation. 179 TABLE IIt. ‘WIIOJ }X9U JY} DAVY VM ‘S}OYOVIG JO apIs}No Jas JUNOWL sures sy} Aq IOYAr 94} SUTA[GIjNw Woy} pue ,(9Ay — PY) 9p AQ UII} YOVd SUIPIAIG » “HOIPESIIZIS DAIJISOM JO SONI DOAIS YIM SutZEIIdyoOd VaYM ‘[VATAIMS 93}vBoId9S JO suTIOJ VAY oy} Aq peonpoid }[Nser paurquios vy} puy shy} pur ‘AT aI[qQvy, soNporjzUT aM s191[M Pojsosans se ‘ww pue Py WSN ACU 9M ‘VL[NLWIOJ Sty} Ul osuUeYO Au JNOYWM— INy pPéry L ‘spssiq-oind jo Jeqmnu 94} Suleq gq pue ‘spse1q-jjey Jo Joquinu oy} Suteq Hl Siecle 2 WN, at. 1)x ~— N= ee !] SEYSI AY} YOM Jo ‘sutie} wu Zuru1eWO0o 2 a, T “2 1 ‘Mol}VIsues oY} JO Joquinu oy} Aq passoidxo }ey} Sv SUIIe} AU se SuTuTezUOD f° * + + Hep) +] sSaties oy} Jo x ums 94} Aq paydnnur 1—-u2W — WW) py = spee1q-j[ey jo woresIsUEs y3u oy} pue {(94~— JV) X J—-uP@W—W) ¥ = uPW — IV) Y = Speerq-eimd jo uonvisuas yyu ay —'aynay puoras “m2 Aq pel[arjnur spsaiq-oind jo worje19ues snorAsid ay} Surippe pue w(9z — |) AG sposiq-jjey fo Wor}e19N08 snorAoid oy} SurAydnpnur Aq punoj ore uoleisuas Aue jo spssiq-jyey 94} pur ‘9yy — py Aq Spasdiq-aind jo vorje1oues snorAeid oy} SsuTAydnynur Aq punojy oie uoljeI0Ues Auv Jo spsoiIq-aimd sy J.—‘ayny ps4 (+ ES) #4 (eC aC) rae remy