"^^e-^. W^. 'jm^- ^^ "•^ Spjg;^' q[K3i D23 ®hp i. m. 'Ml iCtbrarg Nortij (Harolina ^tuU Initipratty •:.H43i D23 HJONia l31Hdli/Vd~ rv'^"^ i THIS BOOK IS DUE ON THE DATI INDICATED BELOW AND IS SUB JECT TO AN OVERDUE FINE Ai POSTED AT THE CIRCULATIO> DESK. D. H. HILL LIBRARY N. C. STATE UNIVERSITY 50M/2-78 NC: LiOrary naicJign Inheritance in Canaries BY CHARLES B. DAVENPORT, Director of the Station for Experimental Evolution, Carnegie Institution of Washington. WASHINGTON. D. C. Published by the Carnegie Institution of Washington. 1908. North Carolina State Library Gift of «i2^ North Caress State Library Inheritance in Canaries BY CHARLES B. DAVENPORT, Director of the Station for Experimental Evolution, Carnegie Institution of Washington. WASHINGTON, D. C. Published by the Carnegie Institution of Washington. 1908. Carnegie Institution of Washington Publication No. 95. Papers of the Station for Experimental Evolution, No. 10. Munder-Thomsen Press baltimore CONTENTS. A. Statement of Problem 5 B. Material and Methods 8 C. Results 8 Series I. The Inheritance of Crest 8 Statement of Problem 8 Material 8 Results 8 1. Recessiveness of Plain Head 9 2. The Detection of Homozygous Crests and the Gametic Com- position of Heterozygotes 9 3. Baldness 11 Series H. The Inheritance of Plumage-Color 13 Statement of Problem 13 Results 14 1. On Inheritance of Green and Yellow Plumage-Color 14 a. Green x Green 15 b. Yellow X Yellow 15 c. Yellow X Green . 15 2. Inheritance of Ticking 17 3. Inheritance of Yellow x Lizard Coloration 19 4. Inheritance of Cinnamon (Female) x Green (Male) 19 Series III. Inheritance of Characteristics in Hybrids between the European Goldfinch and the Yellow Canary 19 Series IV. Hybrids between the Yellow Canary and Other Species ... 22 D. Summary and Conclusion 23 E. Table of Canary Matings 24-25 F. Literature Cited 26 3 INHERITANCE IN CANARIES. A. STATEMENT OF PROBLEM. The objection has been raised that much of the material used in studies of heredity has been long under domestication, in consequence of which, first, extensive hybridization has occurred, and, secondly, characteristics of an "abnormal" sort have been preserved, and, as a result, conclusions drawn from such material can not properly be applied to feral species as they are evolving "in nature." It is extremely doubtful if this objection has any validity, as I have argued elsewhere (1906). Nevertheless it is well to study heredity widely and to include in the study some undomesticated and semi-domesticated species. On this account, four years ago I began the breeding of certain cage-birds and especially the canary bird {Sermus canarius). The canary is, it is true, a semi-domesticated animal. I say semi- domesticated, for in domestication there are all degrees. The essence of domestication from the standpoint of heredity is long-continued control by man of mating. Many species of birds have been bred in zoological gardens, and various finches — linnets, siskins, goldfinches, bullfinches, etc. — are bred in confinement by fanciers and for commer- cial purposes. Likewise grouse and quail and numerous species of swimming birds have been kept captive through many generations, yet such acclimated animals are ordinarily not regarded as domesti- cated, because the breeding has not been long enough continued nor rigidly enough controlled to produce a number of varieties. Between such acclimated wild species and thoroughly domesticated species, such as poultry, dogs, sheep, and horses, which are hardly to be found in the wild state, the canary occupies an intermediate position. The history of the canary in captivity is given as follows:* It occurs as a wild species in the Canary and the Madeira Islands. The wild species agrees in coloration so completely with the captive ' 'green' ' canary with greenish-yellow breast and without white on remiges and rectrices that only a person with precise and thorough knowledge of both can find any certain distinguishing characteristic. After the Spaniards took possession of the Canary Islands in 1478 they brought many of the products of the islands home, and among others these remarkable songsters; but for a long time they were rare in Europe. *The history has been written by Bolle. e 6 INHERITANCE IN CANARIES. Konrad Gesner, who mentions the bird in his book " De Avium Natura," of which the first edition was published in 1555, had never seen it. According to Olina (1622) only males were, for many years, imported, but in the middle of the sixteenth century a Spanish ship, which presumably carried also some female canaries, was wrecked near the Isle of Elba, and the birds escaped, and populated it and created there a peculiar strain in that they were yellower beneath the chin than those brought directly from the Canary Islands. These birds of Elba were trapped by the Italians, bred in captivity, and sold in Italy, in the Tyrol, and in Germany, in which latter country they were already being bred in captivity in many places in the middle of the seventeenth cen- tury. Already at the beginning of that century Aldrovandi had been able to get the bird as a basis for a figure in his Ornithologiae (1599-1603). From Germany the canaries were, in the middle of the seventeenth cen- tury, exported to England and other countries and were already regarded as improved over the wild species,* but their color was still green. t The spread of canary culture was aided by the fact that they became a society fad. Owing to their high price, they were attain- able only by the wealthy and so became a mark of that class. Ladies received visitors with a canary perched on the index finger and were painted in that attitude, t From the beginning of the eighteenth century there is a constantly increasing output of books devoted to cage-birds in general and canary birds in particular, § so that it is possible to reconstruct their history. *InWilloughby's Ornithology (Ray, 1678), quoting an earlier English author, it is stated : "Canary birds of late years have been brought abundantly out of Germany and are therefore now called German birds ; and these Germafi birds in handsome- ness and song excel those brought out of the Canaries. tin "The Gentleman's Recreation," published in 1677, we find that at that date canaries in England were of a green color. (See Blakston, Swaysland &: Wiener, 1880, 5.) Jin the New York Public Library is a little sociological tract entitled, "Canary Birds Naturalized in Utopia : A Canto." London, ca. 1708. The canto begins : In our unhappy days of Yore, When foreign Birds, from German Shore, Came flocking to Utopia's Coast, And o'er the Country rul'd the Roast : — Of our good People did two-thirds So much admire Canary Birds For outward Show, or finer Feathers Far more regarded than all others. We bought 'em dear and fed 'em well, Till they began for to rebel. §The most famous of early works is that of J. C. Hervieux: "Nouveau traite des Serins de Canarie, contenant la maniere de les & elever les appareiller pour en avoir de belles races ; avec des remarques aussi curieuses que necessaires sur les signes et causes de leur maladies et les secrets pour les guerir." 12 mo., Paris, 1st edition, 1705 [Seditions to 1785]. This work was translated into English, German, and Italian. Serin blond dore Serin blond aux duvets Serin jaune commun Serin jaune aux duvets (race de Panaches) Serin jaune a queue blanche (idem) STATEMENT OF PROBLEM. 7 First it appears that although in 1677 only green canaries were known, as early as 1713 three main color varieties had become estab- lished, in which various subvarieties are recognized. The whole series as given by Hervieux is as follows : Serin gris Serin gris aux pattes blanches Serin gris a queue blanche Serin blond commun Serin aux yeux rouges Hervieux' s "Serin gris" is doubtless of the wild type of coloration; our "green." The "jaune" is doubtless the modern clear or yellow type. Hervieux states that it is (in 1713) among the rare varieties. What the "blond" type is can only be conjectured, but it is probably our mealy, or light, yellow. If this inference is correct three of the modern colors of canaries — green, jonque yellow, and mealy yellow — made their appearance at about the end of the seventeenth century. Their appearance would seem to have been quite sudden — a result indicating their origin by mutation rather than by slow increments in the desired direction.* It appears also that mottled or variegated birds (race de Panaches) were known, and as we shall see later they are probably the result of the crossing of a green bird and a yellow one. Such variegated birds were much esteemed in the early part of the eighteenth century. During the first half of that century the number of color varieties was greatly increased, since Hervieux, in his edition of 1766, recorded 29 color varieties including gris (green), blond (mealy yellow), jaune (jonque yellow), agate, Isabella (buff or cinnamon), blanc (white), panache (mottled), and plein — "qui est a present le plus rare." The histories do not state when the crested form first appeared. Crested birds, like yellow ones, are now bred in captivity in their native islands. The frizzled characteristic found in the Parisian Trumpeter or Serin frise or Dutch frizzle is probably relatively recent, as it is rela- tively uncommon. Likewise of the other varieties (lizards, albinos, etc.), the origin is quite obscure. The introducer of a new variety usually conceals its origin; indeed, he has little to say, as he does not produce or induce the new characteristic, but merely preserves that with which fortune has favored him. The history of acclimated canary birds thus reveals their com- paratively recent domestication and justifies the contention that their characteristics may well be expected to be inherited much as they would be if found in wild birds. The specific characteristics upon which I propose to report in the present paper are two; viz., plumage-color and crest. The matters of *Russ (1906, 6) concludes that the change from green to yellow certainly occurred quickly. 8 INHERITANCE IN CANARIES. form and position, of frizzling, and certain others are not yet ready for a report. The types of color that I have studied most thoroughly are the original green and the yellow. These have been bred pure i7iter se, and with other species. The cinnamon and lizard-color types have been merely touched. As for the crest, this consists of a group of feathers on top of the head arranged so as to radiate from a center between the eyes and forming a small cap covering over the eyes and beak. The questions are: How is the crest inherited, and how is the plumage- color inherited ? B. MATERIAL AND METHODS. My original stock (1904) consisted of 4 yellow hen canaries (one crested) of the short or German (Harz Mountain) type and 2 green birds of the same type. Also 3 yellow cocks (one crested) and 2 greens (one crested). To these each year sundry other canaries were added. These were purchased from a dealer in New York and had been imported from Germany or England. The canaries were bred in a room at the Station for Experimental Evolution, each pair being kept in a separate cage. The usual methods of feeding were adopted. All birds bear numbered leg-bands by which their identity is established. C. RESULTS. Series I.— THE INHERITANCE OF CREST. STATEMENT OF PROBLEM. It is my experience with poultry (1906, 69) and pigeons that crest is alternative in heredity and dominates absence of crest. I wished to test heredity of crest in canaries also to see whether the conclusion that I have elsewhere (1906, 87) reached holds, viz., "dominance and reces- siveness depend upon a relation of the characteristics per se and not upon any relation of the races into which they have been introduced." MATERIAL. Crested and plain Harz canaries were chiefly used, but also a few of the "Norwich" type, which had a flatter and darker crest (plate l.fig. 2). RESULTS. It quickly appeared that crest is alternative in inheritance, for when crested and non-crested birds were paired, the offspring were either well crested or plain-headed and there were no intergrades. This leads to the hypothesis that crest is dominant as in poultry and pigeons. To test this hypothesis I made a number of matings, of which the detail is given in Section E. INHERITANCE OF CREST. 1. Recessiveness of Plain Head. The following table contains, extracted from the general table, those experiments that give an answer to the question whether non- crested heads are recessive to plain heads. All parents are non-crested. Table 1 . — Progeny of Non- Crested Parents. [The superior and inferior letters C (crested) and c (non-crested) indicate the condition of the grandparents, o signifies original stock, of whose ancestry, consequently, nothing is known directly. The numbers in columns "Father" and "Mother" are tliose of the leg-bands.] Crest. Crest. Experi- ment No. Mother. Father. F.xperi- ment No. Mother. Father, Absent. Present. Absent. Present. 401 7o .^O 1 0 618 K 151 8 0 404 /7o /6o 2 0 619 64^ ss'i 11 0 405 /9o 20o 2 0 623 ^^?. K 8 0 501\ 514/ 4o K 11 0 624 7Sl K 3 0 507 ISo 46o 1 0 711 152\ ml 2 0 512 lOlo So 3 0 716 210\ IS5^^ 3 » 605 S9l So 9 0 718 132\ 20l\ 2 0 609 84^ ^^C 8 0 719 100\ 435^^ 2 0 612 K K 1 0 721 339o 209\ 8 0 613 7o 39^ 1 0 723 200\ 1421 5 0 614 615 53% 2So 8 2 0 0 725 412^ 405\ 1 0 Total . . . . . . 102 0 Thus of 102 offspring of two non-crested parents all were non- crested. In table 1 are included several cases — Experiments 605, 609, 619, 623, and 725 — where from one-fourth to three-fourths of the grand- parentage is crested. In these experiments Galton's law calls for an average of ^/ /cast 22.5 per cent (and at most 45 per cent) crested offspring. The 37 offspring are all 7ion-crestcd. Galton's law simply does not apply to cases of alternative inheritance. 2. The Detection of Homozygous Crests and the Gametic Compo- sition OF Heterozygotes. If crest is an alternative characteristic we should expect to find some (one in three) homozygous dominants which always throw only crested birds, whether mated with a crested or a non-crested bird. The following experiments were arranged to test the purity of crested birds. 10 INHERITANCE IN CANARIES. Table 2. — To Test the Purity of Crested Parents. [I 103 186 201 135 142 G wings G Y Y Y G Y Y Y Y G Y Y 0 0 3 1 0 5 1 0 0 0 0 0 3 1 1 0 0 0 1 0 2 0 0 0 0 1 1 0 5 4 8 2 3 2 1 3 2 2 1 13 6 34 * No. 5Scf i.s of YXY origin, but has a green nape, perhaps derived from the grreen crest of its mother. Table 4 shows that mottled coloration yields, upon inbreeding, the pure forms, yellow and green. Table ^.—Mottled X Self. [c^, male; ?, female.] MOTTLED X GREEN. MOTTI^ED X YEI.I.OW. Mottled Parent. Offspring. Mottled Parent. Offspring. Experi- ment No. Green No. Experi- ment No. Yellow No. No. Prevail- ing Color. Mot- tled. Green. No. Prevail- ing Color. Mot- tled. Yellow. 601 nc^ Y 12$ 3 4 604 626" Y 19$ 6 4 603 SOrT G 11$ 1 2 605 89$ Y «rr 2 7 610 61c^ Y = G 54$ 1 1 612 76$ G 51(i^ 1 0 615 53? G 28rr 5 3 619 64$ Y 85d^ 8 3 616 100? G 37rr 2 0 620 69$ Y = G 83c^> 3 1 624 78$ Y 37c^ 1 2 702 269rr Y Bel.$ 0 5 701 61d^ G 207$ 3 1 703 28r^ Y 67$ 4 6 707 74 9 G 206rr 1 1 704 79c? Y 19$ 4 1 711 164$ G 118J* *1 0 709 111$ Y = G 143rr 4 0 714 240rr Y 157$ t4 2 720 193$ Y 169rr 0 2 725 112$ Y t05c? 0 1 22 16 32 30 ♦Also one yellow. f Also one yellow (?) died very young. ""■"■ 'Taleigh INHERITANCE OF PLUMAGE-COLOR. 17 The experiments recorded in table 5 show that when the mottled form is mated with a pure yellow or a pure green the offspring are nearly equally of the two parental colors and none other.* Moreover, the extracted yellows are "pure," since when bred inter se they pro- duce only yellows. The interpretation of the results of breeding plumage-color is not difficult and may easily be brought to accord with Mendel's law. As already stated, yellow is "green" which has lost its melanic pigment. The mottled canary further differs from the green or the yellow in a spottedness like that of the spotted mouse; and as Cuenot (1903) has shown the latter to be due to a particular factor we may expect the same to be true for the canary. Calling the black factor A'' (nigrum) and the mottling factor M, we may assign to the green parent the gametic formula Nm and to the yellow parent the formula 7iM, i. e., it contains the mottling factor, but lacks the melanin necessary to make it show. The gametic composition of Fj is Wwx"?, NM nm and the soma shows black in spots as a green on a background of yellow. On this assumption of two pairs of allelomorphs, we expect in every 16 birds of F2 : 9 mottled, 3 green, and 4 yellow, of which last class 3 are uM and 1 /iw, without trace of the mottling factor. The observed result in Fg agrees fairly well with this hypothesis. When mottled is mated with mottled we get, as table 4 shows, a total of 34 mottled, 6 green, and 13 yellow, expectation being 30, 10, and 13 respectively. The result departs from expectation in so far as there is a deficiency of greens, but a change of 4 individuals from mottled to green would establish complete accord with theory. When a mottled bird is mated with yellow or with green expecta- tion is an equal number of mottled and self-colored offspring. The number of offspring of each class derived from the mottled X yellow cross accords with expectation. Of 62, 32 are mottled and 30 yellow. Of 38 offspring of a mottled X green cross 22, or 58 per cent, were mottled and 16 green. Here, again, is a deficiency of greens, but not a very improbable one. Altogether, the results favor the hypothesis that there are in canary plumage two distinct and distinguishing factors — a black factor and a mottling factor. 2. Inheritance of Ticking. It has been stated above that in mating yellow birds yellow off- spring ticked with black were occasionally obtained. Similarly marked birds were obtained at other times. It seemed desirable to ascertain *One clear exception and one doubtful one are found in the green X mottled rnatings of Experiments 711 and 714 where a yellow appeared among the offspring. 18 INHERITANCE IN CANARIES. whether this ticking is an accident that may be eliminated by further dilution with yellow blood or darkening with "green" blood or whether it is a unit-character like mottling which persists, defying all attempts at dilution. The history of some matings to test this point is given in table 6, in detail. Table 6. Exp. No. Mother. Father. Offspring. No. From Exp. No. Description. No. From Exp. No. Description. Nos. and Description. 621 81 510 Mottled 58 503 Y + N on nape 127, 129, 189, mottled. 188, Y + N patch at base of beak. 190, Y + N spots on head and nape. 605 89 513 Y + N patch on L nape 8 o Y 168, 169, 170, 171, all Y. 135, Y + N spot on R nape and between shoulders. 136, Y + N spot on L wing. 721 339 o Y 209 618 Y + N spot on R nape 271,273, 317, all Y. 270, Y + spot under L eye. 272, Y + neck stripe, L side. 314, Y + spot at L ear. 315, Y + spot over each eye, on R nape and R secondaries. 316, Y + spot at L eye and on L wing. Table 6 may be summed up in the statement that ticked yellow behaves like variegation ; for ticked yellow X clear yellow gives 50 per cent ticked and 50 per cent pure yellow. Ticking differs from variega- tion only in the amount of dark pigments involved. We have already seen that there is probably a determiner for mottling. We now see that the mottling determiner occurs in various degrees which maybe designated M', M", etc. The question arises what determines the degree of mottling in any case ? If all mottling results from a cross of yellow and green why are the proportions of yellow and green so diverse ? Of the fact of this diversity there is no doubt. For example, in Experiment 501 a pure yellow (No. 4 female) was crossed with a pure green (No. 37 male), and of two offspring one was green, except for yellow bands across the back and a yellow belly and breast. The other was all yelloiv except for dark eye-spots, side of breast, and base of perianal fluff. Conse- quently one may speak of the mottling factor as wide in one case and restricted in the other. Individual germ cells vary in the extent of the spots they determine. INHERITANCE OF PLUMAGE-COLOR. 19 3. Inheritance of Yellow X Lizard Coloration. The " Lizard " canary is closely related to the "Green ; " it differs in that the margin of each of the dorsal body feathers is much lighter than the rest of the web — the feathers are "laced." This condition is dimly seen in the green canary, but is much exaggerated in the "Lizard." The light tip may be either yellow (jonque) as in the "Gold Lizard" or white (mealy) as in the "Silver Lizard." A second characteristic of the Lizard is a light area or "cap" on top of the head over the eyes, which, similarly, is either reddish or white. The characters of the Gold and of the Silver Lizard are said to be quite stable in straight breeding. In my experiments (Nos. 507 and 512) I crossed a Gold Lizard (male) with a crestless yellow Norwich canary. One young was obtained. This had the yellow cap of the Lizard parent. The bird was mottled, but the dark feathers were laced (like those of the Gold Lizard) with yellow. When a Silver Lizard (female) was mated with a yellow Harz I got three young, closely alike. All had a cap, but this was yellow instead of silver. All were mottled and the dark body feathers were generally laced. It appears, therefore, from these few experiments, that cap and lacing are dominant over their absence and "gold" is dominant over silver, Z.^"., jonque over mealy. 4. Inheritance of Cinnamon (Female) X Green (Male). In canary hybridization cinnamon has long been known to behave in a peculiar way. A cinnamon male mated with a female of another race may produce some cinnamon offspring; but a pure non-cinnamon male mated to a cinnamon female produces no cinnamons. Also, the offspring of cinnamons bred to greens are often of a better cinnamon color than their parents. My own experience consists of two progeny of a cinnamon Belgium female X green Belgian male. Both are of a beautiful green color and show no trace of the cinnamon color. The female cinnamon seems to be fully recessive to green. Series IIL— INHERITANCE OF CHARACTERISTICS IN HYBRIDS BETWEEN THE EUROPEAN GOLDFINCH AND THE YELLOW CANARY. The statement is frequently seen that it makes a great difference in heredity whether the individuals crossed belong to allied races or to distinct species. Fockc (1881, 473) states that in race-hybrids characters of the parents do not blend as they do in species-hybrids. It is important to know if this law holds universally, and the finches offer a good opportunity to test it. They are easily hybridized and the results of such experiments have often been recorded by writers on cage-birds {cf. Blakston). The commonest of these hybrids is that 20 INHERITANCE IN CANARIES. between the male goldfinch and female canary. These hybrids have been often described and they have been carefully analyzed by Klatt (1901), who used, however, only museum material or descriptions and knew little about the parents of the individual birds examined. Like all other writers on the subject, Klatt lays emphasis on the great vari- ability of the first generation of hybrids — a variability which is in striking contrast to the uniformity exhibited by most first hybrids between domesticated races. The hybrids between the goldfinch and the canary are usually very dark — brown, black, and "green" pre- dominating— but they usually show various yellow and white patches which may be very extensive and, in extreme cases, result in almost entire albinos. This variability demands an explanation. The goldfinch {JFri7igilla cardnelis Linnaeus), as shown in plate 2, fig. 4, is marked on the head by a red patch on forehead and chin, a black eye-stripe and a black cap extending back on to the nape, where it is sharply cut off by a transverse white band. A pair of white areas run up from the throat on the sides of the head to the black cap. On the body, the back and sides are brown, this color extending also all over the breast and upper wing coverts. The rest of the ventral body is white. Yellow areas on the middle of the exposed portion of all quill feathers form in the folded wing a yellow wing band, and the quill feathers are tipped with white. When such a goldfinch was crossed with a crested yellow Harz (plate 1, fig. 2) one of the hybrids was like plate 2, fig. 3. One can see at a glance that the hybrid is not a mere combination of the characters of the two parental forms, but is more like a green canary combined with the goldfinch. First, a rudimentary crest is present. The red of the face has become of a copper color (red + yellow) and the cap is dark greenish (black + yellow). The breast and belly are yellowish as in the "green" canary. The remiges are black with lighter tips — a modified goldfinch character. The yellow wing-bar is present, but reduced, combining the character of the goldfinch with that of the green canary. The sides of breast and wing-coverts are striped, due to a central blackening of the feathers — a character of the green canary. It thus appears that characters of the green canary predominate, but do not replace the more striking characters of the goldfinch. The fact that the hybrids between the goldfinch and yellow canary have many of the distinctive features of the "green" canary has been frequently observed. Darwin, having heard of the streaked feathers of the hybrid, concluded that "this streaking must have been derived from the original wild canary;" and this case seemed to favor his theory of reversion. Klatt (1901, 508) goes further and concludes CHARACTERISTICS IN HYBRIDS. 21 that there is a reversion in some characters to the serin or Girlitz {Serifius hortulatius Koch), probably close to the ancestor of the wild canary. These characters are four: "in der breiten Binde der Spitzen der Armschwingen, den Fliigelbinden der Deckfedern, den Farbung der Schultern, den Saumen der Steuerfedern." But in respect to the first and last of these characters I find in my birds no important differ- ence from the green canary, except a slight yellowing of the lighter areas. The color of the shoulders of the hybrid is, as it were, the sum of the colors of the goldfinch and the canary. As to the second of the differential characters— the yellow wing-bow — this is highly variable in my hybrids and in mottled canaries. We have no reason to conclude that there is reversion to the serin, and it is undesirable to rest with so vague a term as reversion as an "explanation" of the resemblance of the hybrid to the "green canary." But if not reversion, under what rubric shall we place the greenness of the goldfinch X canary hybrid ? First it is to be recalled that the yellow canary is a green deprived of black pigment. When black pig- ment is added from any source it occupies the emptied spaces and so restores the "green" and the black. Consequently we find streaking on the sides of the body in the goldfinch-canary hybrid and black on tail and wings. But the canary contains also a mottling factor and so the hybrid is "green" in certain areas only. The other areas are yellow or else yellow to which the chocolate color has been added on the back, wing coverts, and sides, and to which red has been added on the face. The belly, which is white in the goldfinch, remains yellow in the hybrid. How, then, shall we conceive the gametic formula of the gold- finch and the yellow canary ? As the goldfinch contains black (A^), red, and chocolate, its formula may be given as N^R, C, m, while that of the canary is fi, r, c, M, contributing only the mottling character. Then the zygote gives NRCAIas dominants, and the adult hybrid shows, on top of the yellow, black, red on the face and chocolate on the back and the sides. The foregoing theory of the gametic constitution of the yellow helps, moreover, to explain the great variability of the hybrids — corre- sponding to the variability of the mottled offspring of yellow X green. As we have seen that in an extreme case the hybrid yellow X green is practically yellow, so likewise the hybrid yellow X goldfinch is occa- sionally, though rarely, entirely or almost entirely yellow except for the red on the face. Finally, attention must be called to the principle of localization of unit-characters. Red is found almost invariably in the goldfinch hybrid, but always confined to the head region. Chocolate occurs in 22 INHERITANCE IN CANARIES. the hybrid, if at all, only where it is present in the goldfinch. Black, on the other hand, is a color that belongs both to the wild canary and the goldfinch. The yellow canary has merely lost one factor necessary to the production of black in these situations where black occurs in the green canary. When black is introduced by the goldfinch it is laid down (1) in accordance with the goldfinch formula and (2) also in accordance with the green canary formula, but (3) both distributions are controlled by the variegation factor, so that black (like the other pigments) is laid down only over more or less circumscribed areas of the body. Series IV.-^HYBRIDS BETWEEN THE YELLOW CANARY AND OTHER SPECIES. Canary fanciers have been very active in making "mules" between various species of finches. Besides the goldfinch, the linnet {Fri?igilla linota), the greenfinch {Fritigilla chloris), and the siskin {Frmgilla spinus) have been crossed with the canary. The linnet is a prevailingly brown bird, with black, white-edged quill feathers and darker striping on wing coverts and sides of body. The hybrids with the yellow canary are said usually to be dark birds resembling the linnet. Mottled birds sometimes occur, linnet colora- tion showing in patches on the otherwise yellow background. (Blak- ston, 1880, 272). Here the brown of the linnet seems to dominate over the canary green, but the mottling factor of the yellow canary is active. The greenfinch is olive-green above, yellowish-green below, has black remiges edged with yellow (forming a wing-bar) and black rec- trices edged with olive-green, except the four outer tail feathers, which are edged with bright yellow. The hybrids are sometimes dark like the greenfinch, but "highly variegated" are common. Here, again, is seen the mottling factor of the canary. The siskin is streaked greenish above anteriorly and yellowish posteriorly; below is light green in the male and white in the female. There is a yellow stripe over the eye. The sides of body and wing coverts are distinctly striped. The wings and tail are prevailingly black, but the base of the rectrices and a wing-bar and wing-bow are yellow. The hybrid with the yellow canary (plate 1, fig. 2) closely resembles the siskin — the dark beak, the yellow supraorbital stripe, the striping, even to the lower tail-coverts, are all present. In my hybrids the wing-coverts and rump are green as in the green canary. Here again the hybrid shows the so-called reversion phenomena. Mottling occurs in the hybrids under certain conditions, but the usual type is all dark (plate 3, fig. 6). The foregoing descriptions show first that in all hybrids between the yellow canary and a finch there is a tendency to "reversion" — a SUMMARY AND CONCLUSION. 23 result that falls into the same category as the "reversion" of the goldfinch hybrid. In all cases the hybrids with the yellow canary are very variable and frequently show more or less of the canary yel- low. This is due to the mottling factor of the canary to which refer- ence has been so often made. That it is the yellow canary which contains the mottling factor and is the source of the variability of the hybrids is shown by the facts that (1) hybrids with the green canary do not vary in this fashion, and (2) hybrids between any two species of finches — of which many are bred by fanciers — are "cast in one mold." D. SUMMARY AND CONCLUSION. The history of the domestic canary shows that it has been intensely bred for only about 250 years and may therefore be regarded as a rela- tively recently acclimated species when compared with poultry that have been bred for over 2,000 years. Nevertheless distinctive characters have arisen which behave in Mendelian fashion. Crest is dominant over plain head. Baldness is a unit-character and is recessive to perfect crest. The yellow canary is derived from the original "green" canary by the loss of black. It carries a mottling factor. Consequently when the yellow canary is crossed with a pigmented canary or with a finch the hybrids are mottled. The mottling is not a fixed pattern. The spots vary in position and relative size — they may cover nearly the whole body or they may form a mere "ticking." The degree of mottling is inheritable. Ticking behaves as a unit-character. Mottling is a heterozygous character and throws mottled, clear yellow and self-greens. The principle of localization of the units of a complex plumage must be recognized. The cap of the Lizard canary, the red face of the goldfinch, the shoulder striping of the green canary are not only unit-characters but they occur only at their proper localities and in their proper forms in the body plumage. In mottled canaries the presence of black on the shoulder means striping, on the wing it means dead black, white-laced remiges, on the mid-breast it means a uniform olive color. The plumage of a yellow canary may be compared with a letter that has been written with invisible ink. Wherever the developer acts (i. e., the black pigment of the green canary is added) that which is written appears with all of its idiosyncrasies. Cold Spring Harbor, N. 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LITERATURE CITED. Aldrovandi, U. 1599-1603. Ornithologi^, etc. Bononias. Anonymous. 1708 [?]. Canary-Birds Naturalized in Utopia. A canto. London, n. d. 1735. The Bird-Fancier's Recreation: Being Curious Remarks On the Nature of Song-Birds, etc. London. Blakston, W. a. 1880 [?]. The Illustrated Book of Canaries and Cage-birds. London. Casseli, n. d. [The Britisli and Foreign Cage-I3irds by W. Swaysland and A. F. Wiener, respectively.] CUBNOT, L. 1903. L'heredite de la pigmentation chez les Souris noires. Archives de zoologic exper. et gen. [4], tom. i, Notes et Revue, p. xxxiii-xii. Darwin, C. 1876. The variation of animals and plants under domestication. Second edition, revised, vols. I, II. Ncw^ York : D. Appleton & Co. Davenport, C. B. 1906. Inheritance in Poultry. Publications of the Carnegie Institution of Wash- ington No. 52 (Papers Station for Experimental Evolution No. 7). 1906 «. The Mutation Theory in Animal Evolution. Science, n. s. , xxiv, pp. 556-558, Nov. 2, 1906. FOCKE, W. O. 1881. Die Pflanzen-Mischlinge. Ein Beitrag zur Biologie der Gewachse. Ber- lin: Borntraeger, iv-|-567 pp. Gesner, C. 1617. Historiae Animalium. Liber II, qui est de Avium natura, etc. Franco- furti. [Edit 1, Fol. Figuri, 1555.] Godman, F. du C. 1870. Natural History of the Azores or Western Islands. London: van Voorst, v-l-358 pp. Hervieux de Chanteloup, J. C. 1705. Nouveau traite des serins de canarie. Paris. [The reference in the text is from the edition of 1713 — the 2d edition. The Station for Experi- mental Evolution has the edition of 1766 — the fourth. An English translation appeared in London, 1718.] Klatt, G. T. 1901. tJber den Bastard von Stieglitz und Kanarienvogel. Arch, fiir Entwicke- lungsmeclianik der Organismcn. xii. 414-528. Taf. ix. August 2d and September 10th. Krukenberg, C. F. W. 1882. Vergleicliend-physiologische Studien. Zweite Reihe, Zweite Abtheilung. Heidelberg: Winter. 96 pp. Noorduijn-Groningen, C. L. W. 1905. Die Farben- und Gestaltskanarien. Magdeburg: Creutz. vni+152 pp. Olina, G. p. 1622. Uccelliera, etc. Roma. Ray, J. 1678. Tlie Ornithology of Francis Willoughby, etc. London : Martyn. 442 pp. 78 tab. Russ, K. 1906. Der Kanarienvogel: Seine Naturgeschichte, Pflege und Zucht. 11 Auf. Bearbeitet von R. Hoffschildt. Magdeburg : Creutz. 244 pp. PLATE 1 ^^ ■/ / FIG. 1. CRESTED GREEN" CANARY (NO. 1 1 8 a") FIG. 2. CRESTED YELLOW CANARY, MEALY TYPE (NO. 67?) PLATE 2 A MOtM • CO SALT < - FIG. 3. HYBRID BETWEEN GOLDFINCH (FIG. 4) AND CRESTED YELLOW CANARY. TYPE OF FIG. 2 (NO. 203.,') FIG. 4. EUROPEAN GOLDFINCH, FATHER OF NO. 203 (FIG. 3) PLATE 3 5. A Hvi iJi lo iv^Lnvour FIG. 5. MOTTLED OFFSPRING OF CANARIES OF TYPES OF FIGURES 1 AND 2. HIGHLY VARIEGATED TYPE (NO. 61 A FIG. 6. HYBRID BETWEEN SISKIN AND CRESTED YELLOW CAri«|^^(NO. 264) CRESTED YELLOW CA^r^^KjNO North CarollTWC^ta Rafeii i 1 DATE DUE i 1 ' GAYLORD PRINTED IN USA. 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