5>*-r-f% '^ *^-. :4'^;.*M;i \ '.-..J ' V . A^- ■:?^- ^0>jM. 4 ', -^■-^V- ..l// v- '•; •^, ■/-■•" ■v:.} ^-.; •5.i .JV W%^ r^- '■■'^- ';r'n- '<:'f i ^rt- :-">L\,^>v JOURNAL OF GENETICS CAMBRIDGE UNIVERSITY PRESS ILnnian: FETTER LANE, E.C. C. F. CLAY, Manager also H. K. Lewis, Gower Street and William Wesley and Son, 28, Essex Street, W.C. ffitimliursti : Km, PRINCES STREET Berlin: A. ASHER AND CO. 1Lrip;is: P. A. BROCKHAUS iSfto Sorb ; G. P. PUTNAM'S SONS Btimtinu nnO iTnlcufta : MAOMILLAN AND CO., Ltd. All riiilits reserved JOURNAL OF GENETICS EDITED BY W. BATESON, M.A., F.R.S. DIRECTOR OF THE JOHN INNES HORTICULTURAL INSTITUTION AND R. C. PUNNETT, M.A., F.R.S. ARTHUR BALFOUR PROFESSOR OF GENETICS IN THE UNIVERSITY OF CAMBRIDGE Volume II. 1912— 1913 Cambridge : at the University Press 1913 ffanibi itrgr : PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS CONTENTS. No. 1 (February, 1912) PAGE Arthur W. Hill. The History of Primula Obconica, Hance, under Cultivation, with some remarks on the History of I'riimda sinensis, Sab. (With Plates I and II) ..... 1 H. Drinkwater. Account of a Family showing Minor-Brachydactyly. (With 15 Text-Figures) . . 21 A. H. Sturtevant. A Critical Examination of Recent Studies on Colour Inheritance in Horses . . . . . . . 41 R. H. CoMPTON. A Further Contribution to the Study of Right- and Left-Handedness. (With 4 Diagrams) .... 53 No. 2 (June, 1912) W. Neilson Jones. Species Hybrids of Digitalis. (With Plates III — V, one coloured, and 45 Text-Figures) . . . . 71 L. DoNCASTER. Notes on Inheritance of Colour and other Characters in Pigeons .......... 89 C. J. Bond. On Heterochromia Iridis in Man and Animals from the Genetic point of view. (With Plates VI — IX, and 7 Text- Figures and 1 Chart) 99 Richard Staples-Bhowne. Second Report on the Inheritance of Colour in Pigeons, together with an Account of some Experiments on the Crossing of certain Races of Doves, with special reference to Sex-limited Inheritance. (With Plate X, coloured) . 131 Frederick Keeble. Gigantism in Primula sinensis. (With Plate XI, and 5 Text-Figures) 163 vi Contents No. 3 (November, 1912) PAGE L. DoNCASTEK. The Chromosomes in the Oogenesis and Spermato- genesis of Pieris brassicae, and in the Oogenesis of Abraxas yrossulariata. (With 15 Text- Figures) . . . . .189 Cliffokd Dobell. Some recent work on Mutation in Micro- organisms. Part I. (With 3 Te.xt-Figures) . . . .201 R. C. PuNNETT. Inheritance of Coat-colour in Rabbits. (With Plates XII— XIV, two coloured) 221 A. H. Trow. On the Inheritance of Certain Characters in the Common Groundsel — Senecio vulgaris, Linii. — and its Segre- gates. (With Plates XV— XVIII, and 4 Text-Figures) . . 239 Frederick Keeble and E. Frankland Armstrong. The Role of Oxydases in the Formation of the Anthocyan Pigments of Plants. (With Plate XIX, coloured, and 5 Te.xt-Figures) . . .277 No. 4 (February, 1913) A. H. Tkow. Forms of Reduplication : — Primary and Secondary. (With 6 Text-Figures) 313 Clifford Dobell. Some recent work on Mutation in Micro- organisms. Part II. ....... . 325 K. ToYAMA. Maternal Inheritance and Mendelism. (First Con- tribution.) (With Plate XX) 351 Vol. 2. No. 1 February, 1912 JOURNAL OF GENETICS EDITED BY W. BATESON, M.A., F.R.S. DIRECTOR OF THE JOHN INNES HORTICULTURAL INSTITUTION AND R. C. PUNNETT, M.A. PROFESSOR OF BIOLOGY IN THE UNIVERSITY OF CAMBRIDGE CAMBRIDGE UNIVERSITY PRESS LONDON : FETTER LANE, E.C. C. F. CLAY, Manager also H. K. LEWIS, 136, COWER STREET, W.C. WILLIAM WESLEY AND SON, zS, ESSEX STREET, W.C. EDINBURGH : 100, PRINCES STREET PARIS : LIBRAIRIE HACHETTE & c"^. BERLIN : A. ASHER & CO. LEIPSIC : BROCKHAUS NEW YORK: G. P. PUTNAM'S 'SONS BOMBAY AND CALCUTTA : MACMILLAN & CO., LTD. Price Ten Shillings net [Issued February 29] Reports to the Evolution Committee of the Royal Society Eeports I — V, 1902 — 09. In one volume bound in cloth, with index, price 20/-. To he had from Harrison and Sons, St Martin's Lane, London. This volume contains the complete account of the researches in genetics made during the last decade by W. Bateson, E. R. Saunders, R. C. Punnett, F. M. Durham, D. C. E. Marryat, and I. B. J. Sollas, as well as contribu- tions by C. C. Hurst, L. Doncaster, and M. Wheldale. The continuation of most of these researches will appear from time to time in the Journal of Genetics. JOURNAL OF GENETICS A periodical for the publication of records of original research in Heredity, Variation, and allied subjects. Edited by W. BATESON, M.A., F.R.S., Dh-ector of the John Innes Horti- cultural Institution, and R. C. PUNNETT, M.A., Professor of Biology in the University of Cambridge. Volume 1 (1910 — 1911) with 40 plates and numerous text-figures, now ready. Price, in four parts, paper covers, 30s. net, or bound in buckram, 34s. 6d. net. Buckram binding cases can be supplied to subscribers, at 2s. 6d. net. Subscribers' sets can be bound for 4s. Qd. including the case. The Jottrnal of Genetics will be issued in parts as material accumulates, and a volume appearing, so far as possible, annually, will consist of four such parts. The Subscription price for a volume is 30s. net (post free) payable in advance ; separate parts 10s. each, net. LONDON: CAMBRIDGE UNIVERSITY PRESS: FETTER LANE Volume II FEBRUARY, 1912 No. 1 THE HISTORY OF PRIMULA OBCONICA, HANCE, UNDER CULTIVATION, WITH SOME REMARKS ON THE HISTORY OF PRIMULA SINENSIS, SAB. By ARTHUR W. HILL, Assistant Director, Royal Botanic Gardens, Kew. ^ Primula obconica, Hance', was introduced to England from China by Maries, one of Messrs Veitch's collectors who in 1879 sent home seeds fi'om the Ichang gorges, where the great river Yangtse rushes out of the mountains. The plants raised from these seeds flowered in September, 1880=. In the Botanical Magazine, t. 6582 (Sept. 1881), the plant is figured and described under the name P. poculiformis , Hook, f. and in this figure the petals are shown with a simple notch or indentation similar to that of the common Primrose, P. acaidis. The wild specimens collected in China and preserved in the Kew Herbarium all show this character of the simply toothed perianth segments though they exhibit a considerable range of foliar variability. In the description the plant is said to have the habit and foliage of P. cortusoides (see t. 399 and t. 5528) and the calyx of the Himalayan species P. filipes — a native of rocks at Chuka in Bhotan at an elevation of 6500 feet. P. obconica as introduced appears to have been a well-defined plant showing on the whole but little variation and, except for slight diver- gences in the colour of the flowers and character of the leaf margin, to have remained fairly true to type for about the first ten years after its introduction. The finding of the wild plant in China by Maries is best described in his own words : — " When I was travelling in Central China, I was 1 Journ. Bot. 1880, p. 234. 2 Hortus Veitchii, pp. 82 and 292. s,mKA.RY f-ifcvv VORK t-uTANlCAl, Jouin. of Gen. ii 2 Historff of Primula much puzzled how to bring out living plants llOO miles to the coast at Shanghai. I, of course, took plants of the things I thought were best for garden purposes, but Ferns and herbaceous plants were altogether out of the question. I thought, however, that many seeds would germinate if they were kept in soil, so I collected surface soil from Ferns and Primulas, and other plants. This was kept in an old wine box and eventually taken to Hong-Kong. I took this home twelve months afterwards and the soil was ' sown ' in a glass house. The first thing that came up was Primula, ohconica in large quantities, several shrubs, and a lot of ferns'." Sir Joseph Hooker, writing in the Botanical Magazine", states that the plant is probably very variable and that the earliest flowering specimens sent by Mr Veitch were less hairy and had rounder and nearly entire leaves and very much smaller flowers than that figured in the plate. The flowers are of a pale lilac colour with a yellow eye, and the perianth segments, which are rather narrow, .show a deep apical notch. Messrs Veitch' speak of the colour in the virgin species as an "undecided lilac," while according to another writer^ the flowers are said to be pinkish-white and it is suggested that white forms might be raised by careful selection. From a notice in The Garden ", we learn that " the flowers though somewhat small arc of a pleasing mauve tint. The (almost entire) leaves are large and broad and they form a distinct tuft which lies almost flat on the soil." In the Botanical Magazine on the other hand the leaves are represented as upstanding with lobulate- dentate edges''. With these preliminary remarks as to the incidence of variation, the detailed history of our modern forms may now be examined. In attempting to trace the history of Primula, ohconica, under cultivation it will be convenient to arrange the facts under ditferent headings such as colour of the flowers, size, shape, fimbriation of the corolla lobes and doubling and lastly questions connected with hybrid- isation. 1 The Garden, November 22, 1890, p. 470. - Bol. Mag. 1881, t. 6582. » Hon. Veitchii, p. 282. * Gardeiurs' Chronicle, October 28, 1882, p. 565. = The Garden, June 25, 1881, p. 655. " See also Tlie Garden for 1884, September 6, p. 236, the perianth segments are drawn with an apical notch. A. W. Hill Flower Colour. For the first few years after its introduction, as has been shown, the flower colour is always recorded as pale or undecided lilac (Plate I, figs. 1, 2) or pinkish-white but references to the variable character of the plant are frequent. In 1886 there is a record of plants from the Royal Botanic Garden, Edinburgh, with blooms " ranging from mauve to lilac and frequently pure white \" "N. G." in the following year refers to the variability in flower colour and speaks of a few nearly white forms". In the same note, it is mentioned that " we have observed in two or three of the plants this year a much deeper shade of rose round the eye than previously." This appears to be the earliest record of the appearance of the dark eye which was only found in a few cases among a batch of ordinary forms. The next record of the dark eye is in 1889 when "R. D." (Richard Dean) writes " The variety I have is of a very delicate mauve colour, with a slight purple ring round the eye'." In 1893 mention is again made of a distinct circle of a dark colour surrounding a lemon eye and the lemon eye itself is recorded as a novelty I A "dark carmine shaded eye" is also mentioned in a note in 189o^and a "distinct eye" in the following year^ The "dark eye" is now a very common feature in many of the present day forms and the depth of the colour of the eye tends to in- crease as the flowers remain open (cf Plate I, figs. 8 and 17, Plate II, figs. 27, 30, 32, 34). White variety. The white variety to which references have already been given does not receive further mention in horticultural journals until the year 1896. In that year Messrs Vilmorin Andrieux et Cie' of Paris exhibited "P. ohconica k grande fleur blanche" at the meeting of the French Horticultural Society, on Feb. 27th. This form had fimbriated petals. A pure white form was shown again, together with coloured varieties before the same Society by Messrs Vilmorin on May 2nd 1899*, and was catalogued by Messrs Vilmorin in that year under the name "P. a. grande fleur blanche pur." 1 T. W. Sanders iu Journ. Hon. May 6, 1886, pp. 358, 359, with fig. 66. - "N. G." in Journ. Hart. May 26, 1887. 3 "B. D." in Gard. Chron. November 2, 1889, p. .504. * "A. D." in The Garden, October 7, 1893, p. 327. 5 J. C. Tallack in The Garden, April 6, 1895, p. 240. « The Garden, December 12, 1896, p. 481. ' Rev. Hon. 1896, p. 238. 5 Rev. Hort. 1899, p. 169, "A cote descoloris rose et blanc pur...". 1—2 4 Histonj of Fruuula I am informed by Mr A. W. Sutton that the pure white variety first appeared with his firm in 1899. The next reference to the white- flowered plant is in 1904, when a plant figured in the Gardeners Chronicle^ is described as having " white flowers or as nearly white as possible." Mr Gunibleton also in this year sent "almost white" flowers to the editor of The Garden- raised from seed obtained from Messrs Haage and Schmidt. Further a group of P. ohconica alba was shown by Messrs Veitch at the Temple Show that same year, and it was remarked that ..."never before had been seen so near an approach to pure white"'." P. ohconica has been largely grown by Her Grace Adeline, Duchess of Bedford, and has been the subject of numerous experiments by the head gardener, Mr Dickson. I am indebted to Her Grace for affording me every facility for obtaining information about the culti- vation of the plant at Chenies. The first white P. ohconica arose there in 1903, and its origin would appear to be independent from the white forms previously mentioned since it is alleged that no admixture from outside sources has taken place. In present day collections the white- flowering varieties can usually be easily distinguished by the darker tint of green in their leaves, and by their more delicate and- paler stems. Messrs Veitch have a fine strain of this plant, very similar to those raised by Mr Dickson and others. The variety includes both toothed and fimbriated flowers and is found to come true from seed (Plate I, fig.s. 15, 16, 19, 20). Rose variety. A very distinct break in colour and one of the earliest to arise was started with the development of the rose colour from the original pale lilac and this yielded the remarkable rose-carmine series which includes some of the most striking of our modern varieties. Mr Sutton informs me that the first break from the original lilac was a good rose-pink, seed of which was offered by their house as P. ohconica rosea* in 189-5, and a variety under this name was exhibited at a meeting of the Royal Horticultural Society early in 1896 and was said to be an " undoubtedly most decided break in point of colour." Other references are to be found in Tlte Garden about this time'^ (cf. Plate I, figs. 3—5). In 1897 Mr T. S. Ware" also showed a variety 1 Gard. Ckron. 1904, p. 244, Fig. 103, p. 245. ^ The Garden, 1904, January 9, p. 18, see also /. c. April 7, p. 304. 3 ..X." in The Garden, July 2, 1904, p. 3. ■> The Garden, February 20, 1897, p. 143 "E. J." 5 The Garden, November 7, 1896, p. 383, see also August 7, 1897, p. 110. « The Garden, March 13, 1897, p. 197, March 20, 1897, p. 216. A. W. Hill 5 with flowers of a " warm rose tint " and the managing director of Ware's Nurseries has sent me the followinsf account of the origin and development of their rose-coloured forms : "The first noticeable tendency (with us) of Primula obconica to produce other than the pale lilac flowers occurred about twenty years ago, when amongst a batch of many hundreds of seedlings (from seed obtained from a Continental source), five or six plants showed a deeper coloration beyond anything we had ever previously noticed. These plants were isolated, cross fertilized, and the seed saved separately from each plant. The resulting seedlings produced a fair amount of rose colours of varying shades. The best of these as regards depth of colouring, size of bloom, and good habit were retained, the remainder being destroyed. These were again cross fertilized and the selection carried on as before. Year after }'ear seedlings were raised by this means (the colour becoming more intense each generation) until at last we reached the climax, that is, a deep self-rose of good habit and large flowers. In each successive batch of seedlings we always found one or two plants with extra deep and a greater number of serrations and of good colour. These we made the seed-bearing parent, as after repeated trials we found the serration was more pronounced in the offspring than when these plants were used as pollen bearers only, and so together with the development of the desired rose colour, the fimbriation or excess of serrations was proceeding at the same time in each successive generation " (cf Plate I, fig. 3). Messrs Vilmorin of Paris had also at this time produced a rose form of P. ohconica^, but it is not possible to determine whether the rose break originated in one place only or in several nurseries at about the same time, though the latter suggestion seems the more probable". A form apparently very similar to these early rose or pink varieties is still to be seen planted out in the beds of the Temperate House at Kew where it has been grown undisturbed for many years (Plate I, figs. 3—5). A rose variety^ formed the starting point of the experiments carried out in the gardens of the Duchess of Bedford. ' Rev. Hort. 1897, p. 141, announced in theii- catalogue for 1898 as "P. obconica k grande fleur rose vif." ^ See also I. c. 1899, p. 548, with coloured plate. The variety "Bose Chamoise" was catalogued by Messrs Vilmorin in 1900. ^ P. obconica rosea, seed purchased from D. W. Thomson, Edinburgh, who obtained seeds from Stewart and Co., Covent Garden. The origin of the seed was very possibly continental. 6 History of Primula A further improvement in the production of a red obconica " Vesuve," was due to Messrs Rivoire, pere et fils', and the variety "Vesuve" pro- duced in 1903 was said to surpass in colour all other reds and carmines. Messrs Rivoire, like Messrs Vilmorin, attribute all their improvements simply to selection. In the next year Messrs Barr and Sons exhibited their "Crimson King^," described as a "rich deep lilac-crimson, a decided advance in coloured obconicas," followed in 190.5 by their "Crimson Queen'*," a "deep crimson-rose." In the note on this plant it is remarked that the fir.st pink and rose forms were thought to have been .sent from a large Fifeshire garden ten years before. Rover^ had also an assortment of reds from " Zartesten blassen Rosa bis zum dunkelsten Karmin." Messrs Sutton and Sons chronicle the production of a crimson form in 1906, and ou Nov. 23, 1909 they exhibited a remarkable variety °, " Sutton's Fire King," having terra-cotta crimson flowers with a yellow throat surrounded by a darker ring. The origin of this form is also attributed entirely to selection. Herr Georg Arends of Ronsdorf, who has kindly supplied information about his experiments with P. obconica, obtained varieties which he has named "rosea" and "kermesiana" (Plate II, fig. 35). In a letter dated Nov. 24, 1909, he writes " The last quite new colour I gained was the var. 'Feuer Konigiu' (Fire queen), hat came out of the Kermesiana in four or five years' work. There is a kind of salmon-orange in the crimson of this variety and I think it will be possible to have a pure salmon-pink shade from it in a few years." So much interchange has gone on in recent years between nurserymen that it is highly probable that many of the varieties recorded by different houses have a common origin and are really the same plant. A dark claret form to which the name "Chenies excelsior"" has been given has the darkest coloured flower of the red series so far seen (Plate II, figs. 37, 38). Violet-blue varieties. One of the most recent and striking colour shades which have been evolved in P. obconica under cultivation is a decided violet-blue shade which is now a well-marked and good colour. The improvement in this direction in England appears to be due very largely to the efforts of Mr Dickson. 1 am informed that a small 1 Rev. Hon. 1903, p. 442, see also Rev. Hort. 1906, p. 487. 2 Garden, 1904, March 24, p. 261. ■■' Garden, 1905, February 9, p. 116. ■• Gartenflora, 190.5, 54, p. 82 ; see also idem 1903, p. 204. 5 Garden, 1910, April 9, p. 179, with plate. " Gard. Chrun. 1911, April 29, p. 268. A. W. Hill 7 flowered blue variety was raised a Chenies in the autumn of 1904, and this was followed by the production of a large-flowered blue form in 1906 (Plate I, figs. 10 — 12). A variety named coerulea, remarkable for the blue colour of the flowers, was shown by M. Ferard' at the French Horticultural Society, October 1907, and the production of a similar variety in France is of interest as it seems almost certain that the blue colour has been developed quite independently in two different places. Herr Arends has also produced a blue form and he says in his letter " out of the wJnte I raised the blue, beginning with plants which only showed a slight bluish hue in the bud. It took about ten years to bring this colour out clearly." Unfortunately, Herr Arends has not supplied exact dates of the origin of his varieties, but it seems clear that his blue has had no connection with the similar English variety and may possibly have been independent of Ferard's var. coerulea. Magenta and deep purple forms (Plate II, figs. 22 — 26) have also been produced and should perhaps be more properly regarded as belonging to the red than to the blue series. Size of flowers. The increase in the size of the flowers was one of the first of the changes noticed in P. obconica after it had been under cultivation for a few years. In 1887- a few plants were reported to have produce! flowers nearly double the size of the original plants. In France the tendency to variation in this plant does not appear to have received much notice until 1892^ In this year M. Lille of Lyons brought out a variety grandiflora, and in the following year a variety with flowers larger than the type was produced and fixed by Messrs Vilmorin and sent out by them in the year 1894 with the designation " a grande fleur amelioree." In England in this same year plants grown at Gunnersbury Park are reported to have had flowers which approached very closely in size to those of the ordinary Chinese Primula^. In 1895, however, Mr Tallack, writing in The Garden^, expressed the view that there had been little or no advance on the best flowers of former years, and that 1 Rev. Hon. 1907, p. 531. 2 Journ. Hort. 1887, May 26, p. 417 (N. G.). See also The Garden, 1886, March 13, p. 241, and Gard. Chroii. 1890, February 8, p. 175 (D.). 3 Rev. Hort. 1897, p. 374, 1899, p. 548, ibid. 1893, p. 123. * The Garden, 1893, March 25, p. 242 ; see also ibid. p. 327. 5 The Garden, 1895, April 6, p. 240. 8 Hisfoi'!/ of Primula it was not likely that further advance would take place owing to the difficulty in obtaining seed from the better varieties. Herr Arends who commenced experimenting with P. uhconica in 1888, says that by careful selection and inter-crossing of the best strains he first succeeded iu obtaining his var. grandiflora with larger pale- lilac flowers and that this was followed by various colour breaks in later years. At the present day the increase in size of the flowers in comparison with those of the plants originally introduced is very marked. The largest flowers have been noticed principally in pink and lilac-purple shades and have measured as much as 4— .5 cm. in diameter' (Plate I, figs. 13, 15; Plate II, fig. 30). Fimhriation. The commencement of the fimhriation of the corolla segments in P. obconica is a matter of some interest since this form of variation appears to occur, sooner or later, in most species of Primula under cultivation. Such variation of course is particularly noticeable in the cultivated Chinese Primula, and as far as can be ascertained from the earliest records this tendency to fimhriation had already been initiated when the plant was under cultivation in China". In wild species of the genus, except in a few cases, the corolla segments show a simple notch at the apex' but under cultivation fimhriation has developed in P. Forbesii, P. verticillata, P. keiuensis, P. Sieboldii, P. japonica and also in the varieties of the common Primi'ose P. vulgaris. In the allied genus Cyclamen, fimhriation of the petals has also been developed as a result of cultivation*. Another point of interest in connection with the fimhriation of the corolla is that this variation has, without doubt, been developed quite independently in different places, and at different times. The earliest case of which a record has been traced occurred in the garden of Mr J. ' See also Gartenflora, 1904, 53, p. 139, ibid. 1905, 54, p. 82, and Rev. Hort. 1906, p. 487. * The Botanical Register, 1821, torn. .539. 3 Primula JVinteri (Gard. Chron. 1911, March 4, p. 130, Gard. Mag. 1911, March 4, p. 163, with figs.), is of interest in this couuection as the corolla segments are strikingly fringed. P. Stiiartii, P. petioloris and some other species also have fringed corolla segments in the wild condition. * See Thiseltou-Dyer, "The cultural Evolution of Cyclamen latifolium," in Proc. Roy. Soc. LXI. (1897), p. 143. A. W. Hill 9 Crook of Forde Abbey ^ blooms being said to show "distinct evidence of fringing of the edges." It should be added that these plants were supposed to be the result of crosses with P. sinensis but it will be seen later that the evidence in support of this view is very slight. The next record comes from France, about two and a half years later, a plant with fimbriated white flowers being exhibited by Messrs Vilmorin in February 1896^, before the French Horticultural Society. M. Mottet writes in reply to queries addressed to M. Ph. L. de Vilmorin about this v&r. fimhriata: "The variety first appeared here in 1896 in a large-flowering white strain, in the form of slight denticu- lations on the edge of the petals. This was selected carefully and the variety announced in our catalogue in the spring of 1897," he adds that its origin had nothing to do with any seed or plants outside their own stock. In the early autumn of 1897 a var. fimhriata was being grown at Kew^ from seed obtained from Messrs Heinemann of Erfurt (cf Plate I, fig. 3). The fimbriated variety was also produced independently at Kew and the fringed character was attributed to the results of high cultiva- tion. As the variety was not considered an improvement its cultivation and selection at Kew were discontinued. In 1899 Messrs Vilmorin'' were exhibiting this variety with rose-coloured flowers, and from thence onwards a v&r. fimhriata was offered in most seedsmen's catalogues (cf Plate I, figs. 15, 17; Plate II, fig. 80). Mr A. W. Sutton writes that the fimbriated form appeared at Reading in 1901 and he adds " we do not, however, catalogue this, as the fimbriation has the effect of making the flowers look smaller." Double Flowers. One other striking floral variation in Primula obconica has yet to be described, namely the occurrence of double flowers (Plate I, fig. 21). This appears to have originated with Messrs Vilmorin and as far as can be ascertained nowhere else. M. Mottet writing in Le Jardin^ early in 1901 mentions that the double variety was put in commerce in that ' The Garden, 1893, Oct. 7, p. 327. 2 Rev. Hon. 1896, p. 238 ; ibid. 1897, p. 141. 3 The Garden, 1897, September 18, p. 227; Garten/lorn, 1897, 46, p. 143, text fig. 23. ■• Rev. Hort. 1899, p. 169; see also The Garden. 1904, April 7, p. 304; Gard. Chron. 1904, April 16, p. 244. 5 Le Jardin, 1901, p. 89, fig. 52, see also Rer. Hort. 1901, p. 238, figs. 100, 101 ; Journ. Hort. 1901, p. 14. In 1902 Sir Trevor Lawrence received an award of merit, R.H.S., for a mauve-purple coloured semi-double var. of P. obconica, see Jotirn. Hort. 1902, p. 548. 10 History of Primula year, and in a recent letter he informs me that the double variety may have appeared some years before it was sent out, Messrs Vilmorin do not remember exactly, but they state that at first the flowers were rather small and only half double but that since then the variety has been greatly improved in size and duplication of the flowers and that it now reproduces as well as any other variety. The colour is stated to have been pale rose like the type. Herr Arends informs me that he obtained seeds of the double form from Messrs Vilmorin and attempted to improve the variety by crossing with his own plants. In the course of several years he has obtained " larger flowers, stronger growth and rose-coloured flowers as well as the old lilac ones." Reference to modern catalogues shows that there are now several double varieties offered by nurserymen. Doubling of the flowers in the genus Primula as is probably well known, may take place in one of two ways. In the case of P. sinensis the modern varieties such as Crimson King, etc., double the flowers by corona-like outgrowths from the corolla lobes at the back of each anther and the coloured surface of the outgrowth faces that of its corolla lobe or in other words the added lobes show the colours reversed. In tlie old double white variety of P. sinensis, known as P. sinensis var. jiore plena, winch appears to have been produced about the year 1839' and which can only be propagated by cuttings, the doubling is of a "hose-in-hose" character, the colours of the added lobes not being reversed but corresponding in arrangement to those of the original corolla. In P. ohconica the doubling is also "hose-in-hose" and there is no reversal of arrangement and colour as in the modern P. sinensis doubles. P. ohconica, however, sometimes shows a tendencj- to doubling in yet another manner owing to the splitting of upgrowths of the corolla between adjoining corolla lobes, these ridges split towards the centi-e and so tend to produce a kind of corona with the colours reversed, but with this difference that the " corona lobes " alternate with the corolla lobes while in P. sinensis they are opposite to them. This method can at present be hardly considered as more than a tendency towards doubling, for it may only be shown by some of the flowers in an inflorescence ; it is however of considerable interest and it seems possible that by careful selection a new type of double P. ohconica might be developed (Plate II, figs. 27, 29). ' See Paxton's Maijazine of Botany, vi. 1839, p. 262. This sport appears to have arisen at Henderson's Nursery, Pine Apple Place, London. A. W. Hill 11 Variation or Hybridisation. That Primula obconica as cultivated to-day is a totally different plant from the wild species introduced from China in 1879-80 is a perfectly obvious fact, but as to the cause or causes which may underlie the changes which have taken place there is a considerable difference of opinion. Some of those who have worked for many years on this plant and to whom several of our modern improvements are due contend that the amelioration of this species is due in the main to hybridisation with other species of the genus, while others who have been equally successful in raising new varieties protest against this view and claim that the improvements are entirely due to selection and cross- fertilization of the best forms within the species. It is unfortunate that experiments with this plant have been undertaken from the horticultural rather than from the purely scientific point of view and that the results which tend to be matters of conjecture and assumption have been accepted in many cases as proved fact. For there has been a tendency in some quarters to assume that because a given variation appeared to fit in with a preccmceived idea or with expectation, therefore such a variation was due to a definite experiment or series of experiments. In order to arrive at a conclusion as to the right explanation of the course of events displayed by the history of P. obconica it will be necessary to examine the evidence somewhat in detail. In the foregoing pages it has been shown that for some ten to fifteen years after its introduction P. obconica displayed but little tendency to vary. A slight increase in the size and slight changes in the colour of the flowers were recorded such as would be expected under artificial cultivation, but the bulk of the seedlings tended to come more or less true to the original form. According to Messrs Vilmorin' the first variations in P. obconica were noticed in 1892. In England variation both in size and colour is recorded on several occasions between 1886 and 1893'-, but compared with present-day forms the improvement of the plant does not appear to have been very striking until about fifteen years after its introduction. Messrs Wai'e name about 1890 as their starting point, while Messrs Veitch consider the year 1898, in which their Feltham nurseiies vvere opened, as the date from 1 S. Mottet in Le Jardin, 1901, p. 8. - See especially The Garden, 1888, p. •'iSO, 1890, p. 3.54, and 1893, p. 242 ; Journ. Hort. 1887, p. 417 ; Gard. Chron. 1890, p. 175. 12 History of Priinvla which their improvements should be reckoned. Even as late as 1897 "R. D." (R. Dean) writes in the Gardeners' Chronicle (1897, p. 65) that "so far comparatively little variation has appeared among seedlings. The blossoms of some are larger, rounder and stouter than others and there is a tendency to deepen the tints of some individuals to something approaching mauve." As with all new introductions gardeners very soon attempted to " improve " P. obconica by crossing with other species of the genus, and P. sinensis appears to have been tried in most cases as the pollen parent. As early as 1887 it was suggested' that the variations noticed might be due to attempts to cross P. obconica with Alpine auriculas and Primroses though it was considered as unlikely. That P. sinensis pollen was answerable for the improvement in the flowers is put forward in the ease of the first occurrence of fimbriation recorded in 1893-, and several references to the action of P. sinensis are to be found from that date onwards. In 1896^ Dr Masters e.xhibited a "hybrid" at the scientific committee of the Royal Horticultural Society supposed to be the result of crossing P. obconica with the wild form of P. sinensis, but there was apparently very little to distinguish it from the female parent, and in the spring of 1898'' Mr Shea exhibited the result of a similar cross with (?) cultivated P. sinensis before that committee in which the influence of the Chinese Primula appears to have been accepted, though the predominance of the female is recorded. The possibility of hybridising P. obconica with P. sinensis was accepted definitely in Germany and Herr Arends informs me that a fine batch of hybrids was raised at Fiirsten Walde near Berlin in 1893 "with the growth and leaves of obconica and size and colour of sinensis flowers." He adds in a further letter that the plants had the " large brilliant flowers of sinensis. They represented in perfection that which we had tried to get for so many years." These plants all died without having been described or figured and it is not now possible to say whether they may or may not have been hybrids, but in the light of our present knowledge it would appear to be a matter of considerable doubt. Herr Arends states that he has made this cross again and again but without result and Messrs Sutton, Veitch and Vilmorin'' all express the ' Journ. Hon. 1887, p. 417. "- The Garden, 1893, p. 327. s Ganl. Chron. 1896, pp. 600, 790. ■• Gard. Chron. 1898, p. 119. = See Le Jardin, 1901, also The Garden, 1897, pp. 193, 197, 213, 216, 227, 394 ; 1899, pp. 144, 3G6 ; 1910, Lxxiv. p. 179: Rev. Hon. 1899, p. 548 ; 1906, p. 487. A. W. Hill 13 opinion that no hybridisation has ever taken place between P. obconica and P. sinensis. Mr Valentine, managing director of Messrs Ware's Nurseries, also says that all their improvements are regarded as being due to selection and cultivation. M. Mottet points out that the failure to produce artificial hybrids in the genus Primula is all the more curious since many natural hybrids in the genus are known as for instance among Alpine species and with P. officinalis, P. acaulis, and P. elatior. It has been suggested once or twice that P. obconica and P. sinensis may have hybridised naturally in the same way that P. kewensis arose in the first instance', but this view is opposed by M. Mottet", who even goes so far as to say that even P. kewensis cannot be considered to be a hybrid. This latter case has, however, been proved more than once by artificial crosses carefully made at Kew^ Besides P. sinensis various other species of Primula have been used in the attempt to produce hybrids such as Alpine auriculas and prim- roses'*; P. floribunda, P. verticillata, P. japonica, P. farinosa, P. cortu- soides, P. sikkimensis'', etc., but with regard to all these it is stated that though seedlings were often obtained there was no evidence of hybridi- sation. In an account of an attempt to cross P. obconica with a well-coloured form of P. Sieboldii cortusoides "J. H. W." writes that the latter plant was used as the seed parent and every care was taken to prevent self- fertilisation. Seed was duly formed but the seedlings were nothing but P. Sieboldii cortusoides'^. Several interesting varieties have been exhibited in recent years by the Duchess of Bedford; Mr Dickson, the head gardener, started the experiments in 1901 with a fimbriated variety of P. obconica and pollen of Polyanthi, Primroses and P. Sieboldii in varieties was used, later the pollen of P. cortusoides, P. sineiisis and P. rosea. Mr Dickson claims that his results are due to the use of P. sinensis pollen and that one plant shows distinct evidences of the effect of P. rosea. In April, 1911, Mr Dickson showed a plant at a meeting of the Royal Horticultural Society' under the name of " Chenies excelsior" (Plate II, figs. 37, 38) ■ See Rev. Hon. 1906, pp. 418, 449, fig. 176, where M. Grignan puts forward this suggestion to explain the origin of P. obconica siiperba raised by M. Nonin. - Rev. Hon. 1906, pp. 498, 499. 3 gee Kew Bulletin, 1910, p. 325. * Journ. Hon. 1887, p. 417. = The Garden, 1897, p. 193. « Gard. Chron. 1897, p. 128. ' Gard. Chron. April 29, 1911, p. 268. 14 Historij of Primula and he informs me that the pollen of P. japonica was used to fertilise the deep red-flowered plant of obconica mentioned above which was thought to show evidence of the influence of P. rosea. In general habit however the plant shows no trace of P. japonica either in leaves or flowers. The flowers are of a dark claret-magenta colour not more intense but not unlike that which has been produced by other growers. The inflorescences tend to become whorled as in P. japonica but this occurs not uncommonly with robust plants of P. obconica towards the end of their flowering season. The results achieved in the short space of about eight years are certainly very remarkable, but except for colour changes in the flowers there appears to be no evidence to support the view that the plants should be considered as hybrids especially as similar series of forms are known to have been produced elsewhere by selective methods alone without any recent attempts at hybridisation. Yet another species of Primula, namely P. megasaefolia from the Caucasus, is claimed to have been successfully hybridised with P. ob- conica. Herr Arends of Ronsdorf writes that he started working with P. 'megasaefolia, then recently introduced, about the year 1902 and produced in course of time the strain to which he gave the name P. obconica gigantea. Professor Pax to whom some of the plants were sent accepted them as hybrids between P. obconica and P. megasaefolia and in his account of the genus in the Pflamenreich^ has given the name P. Arendsii, to this supposed hybrid. In habit this gigantea strain undoubtedly shows some differences from the ordinary grandijlora type in its stouter leaves and pedicels, but the flowers both as to calyx and corolla are those of P. obconica and the plants do not appear to show any character which can be definitely attributed to the influence of the pollen of P. megasaefolia. Forms of P. obconica closely resembling the gigantea of Arends appear to have been raised in different nurseries and by other means about the same time. P. obconica robusta raised at Lyon, for instance, by M. Choulet, is stated to be the same thing as P. obconica, gigantea, but to have been produced entirely as a result of selection, Messrs Rivoire of Lyon write as follows on this subject : " Vous avez raison de mettre en douto I'origine supposee de cette Primevere et de vous refuser a croire a une hybridation; c'est d'ailleurs, la aussi, I'avis de I'obtenteur. Nous ne pouvons que vous confirmer ' Dm Pfianzenreich, iv. 237, Primulaceae, p. 346. There is also a note in Garteiijiora, 1908, 57, p. 632 on P. obconica gigantea rubra, "the first true dark red hybrid of the new gigantea race." A. W. Hill 15 daus votre opinion en vous disant que nous avons, depuis I'appai'ition du Primula obcoaica, tente des hybridations avec un grand norabre de Primeveres. Nous n'avons jamais reussi, efc les varietes que nous avons mises au commerce, telles que Vesuve (a fleurs rouge carmin) et robtista, ont e'te obtenues uniquement par voie de selection. " Nous connaissons d'autres horticulteurs qui ont tente de leur cote des hybridations, mais egalement sans succes. Aussi ne croyons-nous nullement a I'origine hybride signalee par I'horticulteur allemand qui annonce le Primula obconica gigantea. "A ce propos, nous vous serions obliges de rappeler que le Primula obconica robusta, que nous avons annonce I'an dernier et qui a ^te obtenu par M. Choulet, chef des cultures florales du Pare de la Tete- d'Or, presente absolumeut les memes caracteres que ceux qui sont signales pour la variete gigantea, c'est-a-dire feuilles de consistance ferme, fleurs de dimensions tres grandes (les plus grandes connues 5 centimetres de diametre) de couleur blanc lilace, ombelles enormes et surtout tiges rigides, qui lui ont fait donner ce nom de robusta^." Whatever may be the explanation of some of the forms of P. ob- conica which have been obtained, it is evident that numerous attempts have been made to effect hybridisation with other species and that a gi-eat deal of work has also been done on the lines of selection and cross fertilisation of the best varieties. In the cases of the assumed hybrids it is remarkable that the results, whatever species may have been the pollen parent, are all strikingly similar and only a better form of undoubted P. obconica has been obtained. Further the forms alleged to have been produced b}' hybridisation can hardly be distinguished from those produced by selection. In this connection also it is worthy of note that in the only case on record where the pollen of P. obconica was used the seedlings raised were purely of the type of the female parent^ (P. Sieboldii cortusoides). The experiments in hybridi- sation appear to have been made with proper care in many cases and the conclusion seems to be suggested that the pollen may in some way stimulate the development of the ovule without effecting hybridisation The case of the orchid Zygopetalum Mackayi^ crossed with the pollen of other genera but always yielding seedlings closely resembling the female parent may perhaps be considered as a somewhat parallel case. It is true that Arend's gigantea strain shows a stoutness in the leaves which is more marked than in the ordinary forms and there is 1 Rev. Hon. 1906, p. 487. '- See p. 15, and Gard. Chron. 1897, p. 128. ^ See Journ. E. Hort. Soc. xxi. 1897, pp. 476, 477 ; Orchid Review, vi. 1898, p. 19. IH History of Primula also the case of a peculiar claret-coloured, small-flowered form produced by Mr Dickson, which is unlike any other variety I have met with. This latter plant was the only one of its kind produced by a cross alleged to have been made by P. obconica and P. rosea splendens. The leaf of this plant also differs somewhat from the normal though it is quite like that of some of the wild specimens preserved in the Herbarium at Kew. The whorled character of the inflorescence, also, which has been developed in the variety "Chenies excelsior," cannot be accepted as an indication of hybridisation with P. japonica since it may occur in uncrossed plants. The evidence for hybridisation in P. obconica cannot therefore be regarded as convincing. A careful series of experiments have been conducted at the John Innes Horticultural Institution at Merton in which the pollen of eight species of Primula has been tried. The results so far obtained tend to show that good seed has been produced only with the pollen of P. obconica itself all other crosses being failures, and this corresponds with the results of similar experiments made at Kew. It is just possible however in view of the conflicting evidence that further careful experiment might demonstrate some form of hybridisation for it may be, as Doncaster' suggests iu dealing with the question of crossing between species, that the multiplicity of characters concerned makes analysis very difficult and thus the evidence of hybridisation may not be apparent. It has been pointed out above that the difficulty of producing artificial hybrids in the geuus Primula is somewhat remarkable in view of the fact that natural hybrids are not uncommon between certain species. Whether any natural hybrid between P. obconica and any other species exists is not certainly known but a specimen preserved in the Kew Herbarium collected by Wilson (no. 4052) in Western China suggests such a possibility. Mr J. F. Duthie who has kindly examined the plant is of the opinion that it may be a natural hybrid between P. obconica and P. cortiisoides ; and in this connection it is of considerable interest to find that a plant (or plants ?) of P. cor- tiisoides came up with the seed of P. obconica collected by Maries in Ichang, the specimen being preserved at Kew. Mr Duthie says of Wilson's plant — "It agrees with the former (P. cortiisoides) in the shape, texture and pubescence of the leaves, but the calyx is that of P. obconica." In its native home P. obconica appears to show a considerable range 1 L. Doncaster, Heredity, Cambridge University Press, 1910, Chap. viii. p. 109. A. W. Hill 17 of variation, though the seed sent to England would appear to have belonged to a fairly uniform type. The plants lately collected by Forrest and referred by him to P. Listeri^, King, are now considered to be the variety glabrescens of Franchet. Many of the specimens, how- ever, show marked differences from the typical P. obconica and are also no doubt quite distinct from P. Listeri, but it seems open to doubt whether all of Forrest's specimens from Yang pi in Western Yunnan are rightly included under P. obconica and whether some should not rather be considered as belonging to a distinct though only slightly differing species, intermediate perhaps between P. obconica and P. Listeri. P. obconica and P. sinensis. The history of P. obconica and of the changes in form and colour which it has undergone in the comparatively few years of cultivation suggests that it may afford a parallel to the case of the long-cultivated Chinese Primula whose origin is still a matter of dispute and con- troversy. Primula sinensis unlike P. obconica was not introduced to this country as a wild plant but as a species which it is believed had long been cultivated in Chinese gardens^. P. sinensis, Lindl., as described and figured in the Botanical Register, 1821, t. 539, as P. prae- nitens, Ker.-GawL, and figured in the Botanical Magazine, 182-5, t. 2564, is not a wild form but a domesticated plant. The first figure published depicts a flower with the corolla segments fimbriated and it is of interest to notice that the later illustration in the Botanical Magazine shows the corolla segments with the notched apex and the plant is in general characters very similar to P. sinensis stellata of to-day. The two pictures are of interest in connection with the history of P. ob- conica, P. Forbesii, P. jajionica, P. cortusoides, P. Sieboldii, P. kewensis, etc. The amelioration of P. sinensis both as to flower colour and shape ' See Gard. Chron. 1909, November 20, p. 544, with figure. - The following account of Primula 'praenitens is given in the Bot. Reg. vii. 1821, t. 539. " It had been brought by Captain Kawes from the gardens at Canton, where it had probably found its way from some far more northern quarter of the Chinese Empire. Samples in a dried state had been previously submitted by Mr Reeves, a gentleman in the employment of the East Indian Co. at Canton." In the figure the corolla segments are fimbriated and the calyx has many lobes ; the account continues — "The plant not having been known in its wild state, can we be sure that the multiplication of the segments of the calyx does not arise from luxuriance induced by exotic cultivation?...." Journ. of Gen. ii 2 18 History of Primula and the remarkable leaf development have proceeded steadily since its introduction so that now many of the cultivated races are very distinct from the plants introduced about 1 (S21. What we may ask was the earlier history of tho plant under the hands of the Chinese ? Is it too great a step to take to consider that the j)lant found by Henry in the limestone gorges of Ichang is really the original wild typo of this species? I for one, in the light of the history of P. ohconica, am inclined to think that it is not too great, and that we have in this little plant with its lilac flowers the true wild type of the species. Some corroboration seems to me to be given to this view by the variety flore pleno of P. sinejisis. This plant somewhat closely resembles Henry's wild type in foliage and may be considered as offering a parallel to the old-fashioned double white and double lilac primroses which in the ilini past must have been derived from P. acaulis. P. sinensis also offers another interesting parallel to P. ohconica in respect of the old double white varietj' since it appears that this arose as a sport about the year 1839 after P. sinensis had been in cultivation about eighteen years. P. ohconica has also yielded a similarly con- stituted double variety as a result of cultivation about twenty years after its introduction. Conclusion. The conclusion to which one is led from the investigation of the history of P. ohconica under cultivation would therefore appear to be that the amelioration and development in form and colour of the Howers, etc. which have taken place during the past thirty j'ears must be attributed to selective processes. The evidence which has been adduced in support of theories of hybridisation with other species is not sufficiently confirmed by facts to justify its acceptance. In view, however, of certain doubtful points and of .some interesting questions as to the influence of foreign pollen in effecting fertilisation it would seem desirable to suspend full judgment until the results of further careful experiments in the fertilisation of P. ohconica witii foriMgn pollen have been obtained. A. W. Hill 19 CHRONOLOGY OF P. OBCONICA. (1) CoUection of seed in China (2) Plants flowered in England (3) White flowers first recorded (4) Dark eye first noticed . (5) Increase in size of flowers (6) Var. grandiflora, M. Lille (7) Fimbriation first recorded, Mr J. Crook (8) Rose-flowered variety [P. ohconica rosea) Messrs Sutton (9) White variety second record (10) Fimbriation second record, Messrs Vilniorin (11) Rose-flowered variety, Messrs Vilrnorin (12) Pure white flowers, Messrs Sutton (13) Double flowers first put on the market (14) Red-flowered var. " Vesuve," Messrs Rivoire (15) Pure white flowers, Duchess of Bedford (16) Pure white flowers, Messrs Veitch (17) "Crimson King," Herr Arends and Messrs Burr (18) Small Violet Blue variety. Duchess of Bedford (19) Large (20) Var. cocrulea, M. Ferard .... (21) "Fire King," Sutton (22) " Chenies excehsior" deep claret, Duchess of Bedford 1879 1880 1886 1887 1887 1892 1893 189.5 1896 1896 1897 1899 1901 1903 1903 1904 1904 ? 1904 1906 1907 1909 1911 DESCRIPTION OF PLATES. PLATE I. 1. Pale lilac-flowered form with toothed corolla segments very near the type originally introduced from China. (3) 2. The same to show the calyx. (3) 3. Fimbriated pink variety similar to the first fimbriated forms produced. (1) 4. Side view of toothed pink variety. (1) .5. The same face view. (1) Figs. 1 — o from plants grown undisturbed for many years in the Temperate House, Royal Botanic Gardens, Kew. Figs. 6 — 12 illustrate the development of the blue strains of P. ohconica. 6. Lilac-blue variety raised by selection, Messrs Veitch and Son, Feltham. (37) 7. Calyx of the same. (.37) 8. Lilac-blue variety with red eye. (27) 9. Calyx of the same. (27) 10. Blue variety raised by Mr Dickson, Head Gardener to Her Grace Adeline, Duchess of Bedford. (38) 11. Calyx of the same. (38) 12. Violet-blue variety with darker stellate eye, raised by Mr Dickson. (28) 2—2 20 Historu of Prhmila 13. Large soft pink flowered variety, raised by Messrs Veitcb. (35) 14. Calyx of the same. (35) 15. Large pure white fimbriated variety, raised by Messrs Veitch. (33) 16. Calyx of this variety showing tendency to fimbriation. (33) 17. Kose-pink variety with crimson eye, fimbriated, Messrs Veitch. (29) 18. Calyx of this variety. (29) 19. Toothed white variety with conspicuous yellow eye, Herr Areuds. (20) 20. Side view of the same flower showing the conspicuously lobed calyx. (20) 21. Double pink variety, hose-in-hose type, raised by Messrs Vilmoriu, Paris, di'awn from a plant sent by Herr Arends. (24) PLATE II. 22. Purple variety with conspicuous yellow eye, Herr Areuds. (21) 23. Side view of the same flower. (21) 24. Calj'x showing its hemispherical shape with unconspicuous teeth. (21) 25. Large-flowered deep purple variety with reddish eye, Messrs Veitch. (30) 26. Fimbriated calyx of the same. (30) 27. Deep rose-pink flowered variety with red eye, showing splitting of the corolla at the sutures between the corolla segments represented by colourless lines, cf. fig. 29, Herr Arends. (10). 28. Calyx of this variety with acuminate segments. (10) 29. Flower enlarged to show the splitting of the raised sutures between the corolla segments producing the commencement of a form of "reversed " doubling, cf. fig. 27. (9) 30. Very large pale pink fimbriated variety, raised by Messrs Veitch. (2G) 31. Calyx of the same. (26) 32. Violet-pink variety with large crimson eye, Messrs Veitch. (28) 33. Calyx of the same. (28) 34. Deep rose-flowered variety with crimson eye, Herr Arends. (7) 35. Crimson variety with yellow eye, Herr Arends. (22). 36. Calyx of the same. (22) 37. "Chenies excelsior" (see Gard.. Citron. April 29, 1911, p. 268), raised by Mr Dickson. (39) 38. Calyx of the same. (39) Specimens of all these and other varieties are preserved in the Herbarium of the Royal Botanic Garden, Kew, and the numbers in brackets at the end of each description refer to the numbers in the Herbarium. JOURNAL OF GENETICS, VOL. IL NO. 1 PLATE ;( \^i -'W •V r .1 ^:i ^' 14 t*^ii-1 fc r ,i>. \ I \7 -^e;; IS V. 1- ; 16 13 Cf - 18 Lr 17 / ^' *^^^ 19 • JOURNAL OF GENETICS, VOL. II. NO. 1 PLATE -Wt^ h 33 r 38 i 29 ACCOUNT OF A FAMILY SHOWING MINOR- BRACHYDACTYLY. By H. DRINKWATER, M.U., F.R.S. (Edin.), F.L.S. In the autumn of last year (1910) a medical friend resident in Liverpool informed me that a relative of his, whilst making his official medical inspection of school children, had seen a boy whose hands appeared to be of the same Brachydactylous type which I had described in a communication to the Royal Society of Edinburgh in November 1907. It naturally occurred to me that some family whom I had already examined had removed to Lancashire ; but as soon as this boy's name was communicated to me I kuew that he did not belong to any of the families already described. In December I wrote to the Headmistress of the school which the boy had attended and received the following reply : — Deo. 29. 10. Dear Sir, Your letter has just reached me having been forwarded from '. The boy, whom yovi refer to, has now left school. His parents live at -. He is a rather peculiar boy, and dull by nature. At school we used to attribute his stupidity to the fact that his parents are related — (first cousins). His short fingers did not seem to hinder his manual work, but they are remark- ably short. I remember being told that the grandfather, on the father's side, had also very short fingers. The boy is now 13 years of age and is apprenticed to a joiner. Dr very kindly ofiered to have the boy's fingers examined at a Liverpool Hospital, but the parents refused their consent. The father is a rather intelligent man and by occupation a salesman at . If I can supply you with any further information I shall be very pleased to do so. I am. Yours faithfully, W. . 1 Names and addresses omitted for obvious reasons. 22 Minor-Brachydactyhj This letter contains three statements which are of interest from the biological standpoint. (1) As to the brachydactylous condition of the boy's hands. (2) The presence of the same condition in a grand-parent. (3) The blood-relationship of the parents. Clearly it was a case for further inquiry. I endeavoured to get soine more particulars by correspondence with some other people who knevv the boy's family but without success. All the information obtain- able was that the boy's parents and all his brothers and sisters were normal (Fig. 1), and the only known brachydactylous member, besides i I (? X 9 I , ' 1 I I ^ sdine brothers and sisters all normal Fig. 1. Erroneous Chart. himself, was his paternal grandfather'. Moreover the parents would not consent to have either a radiograph or photograph of the boy's hands taken. I mention these facts in order to point out the vm-reliability of second-hand information, for it will be seen in the sequel how erroneous the statements were from all sources. Accurate details can generally only be acquired by personal investigations. I have paid two visits to this boy's family and their relatives and though I have not succeeded in persuading them to do all I wished, I have been able to gather together sufficient particulars to make it possible to describe the essen- tial feature of the abnormality, and so indicate its hereditary bearings. I have interviewed most of the boy's relatives including the great- grandmother, grandmother, uncles, aunts, and cousins, and have made several measurements and obtained some radiographs and a couple of photographs. This is most satisfactory considering the great reluctance of these people to do anything which can possibly lead to identification. I am greatly indebted to Mr Thurston Holland for the excellent radiographs which are amongst the best I have ever seen. The abnormality can be traced through five generations. The oldest surviving members of the family amongst the abnormals are the man No. -o in the chart (Fig. 2) and his sister No. 7. No information 1 Three correspondents declared that the ho-^'s parents were normah H. Drinkwatbr •23 g o s^ 24 Minor- Brac/ii/(Jacf>/Ji/ could be obtained from No. 5 as he is bordering on senile dementia. No. 7 was most reluctant to give me any information and tried to mislead me. (As an example, I may mention that on asking about her brother No. 5, and mentioning him by name, she said she had no such brother.) The facts about No. 1 and his five children were however correctly given by her, and were confirmed by her mother, the widow of No. 3, and by other members of the family from tradition. The abnormals are represented by black circles and the normals by white. Where there has been the least doubt as to the individual being normal or abnormal the circle is included in brackets ; these must not be counted in reckoning the ratio of abnormals to normals. The abnormals only are numbered. The information I first obtained to the effect that the schoolboy (No. 21) was the only affected member of his family was not correct, for it is seen that not only is a younger sister (No. 22) of the same type, but the mother also (No. 14): and it was not "the grandfather on the father's side" but the maternal grandmother (No. 7) who had transmitted the abnormality. There were 16 abnormal members of the family alive at the time of my visits and I interviewed each of them, but I regret to say that in some cases I was not allowed to take any measurements. What is the condition of the hands ? The abnormality resembles in many respects that described in my paper "An Account of a Brachydactylous Family^": whilst there are other features in which it differs. The fingers are not so short, and for this reason I propose to term the condition "Miuor-Brachydactyly." The former family will be referred to as "No. 1 family." Fig. 3 shows the hand of the boy already referred to (No. 21). The upper hand is that of a normal brother who is two years his junior (No. 21a). Tiie Brachydactylous condition is sufficiently evident, but that it is not so marked as in No. 1 family is shown by comparing Fig. 4 which is taken from my former paper. As the bones of this boy's hands are not yet fully ossified, it will be well, before describing them from the radiograph, to point out the ' ProCL'cdinys of the I\mj. Soc. of Ediii. Vol. xxviii. Part i. H. Drjnkwater 25 Fif>. 3. Hauds of abnormal and normal brothers. ■ ^B H ■ 1 1 i F" w tt'"5^ H ^Hp ^■^ ^ I I ^ \ 1 H ^r. — ^ w Igijagg i 8 1 B ^ ^ Jsjkjf'' 1 I- ViW { ^^^1 ^^^^^1 ^^^MHP IF^ ■ ». H ^^M ^^L j^-.'SLt^ IP ■HI \,i 1 HH L*4 ■ 3 ^ i 1 I 1 1 1 Fig. 4. Members of No. 1 Family. The lower hand is " Braehydactylous. " 26 Minor-Brachydacttjly peculiarity as seen in the hands of an adult, and for this purpose I shall select the radiograph of a woman, No. 9 (Fig. 5). What chiefly strikes one is the shortness of the middle phalanx in each finger. It is to this peculiarity that the shorteniag of the hand is principally due. Fig. 5. Hand of woman ( > The middle phalanx is very short. In the normal hand, the middle phalanx is intermediate in length between the first and the third. All the phalanges are seen to be distinct and separate : there is no union (ankylosis) of the second to the terminal phalanx, such as occurred in No. 1 family in every case H. Drinkwatbr 27 in the first and little fingers and frequently in the middle and ring fingers also. (See Fig. 6.) Fig. 6. Hand of iidult womau (slightly reduced). Belongiug to No. 1 Family. 28 Minor-Brachydactyly The variations of the bones from the normal type are shown, in out- line, in Fig. 7 where A represents those of a normal finger; B, those of a minor-brachydactylous finger, and C, a brachydactylous finger from No. 1 family. The phalanges are numbered 1, 2 and 3 in each case (3 is the terminal one which supports the finger nail). In C it will be observed that the second phalanx (2) and the third (3) have become united into one bone : whilst in B the second phalanx is short, but remains as a separate bone. ABC Fig. 7. Normal and Brachydactylous Phalanges. (Natural size.) A. Normal. B. Minor-Brachydaetylous. C. Brachydactylous. What is the cause of this shortening ? Each phalanx during childhood shows, normally, a thin bony plate at its base. This plate is called the epiphysis ; it is attached to the larger portion — the shaft of the bone — by an intervening layer of gristle, which, being transparent to the X rays, shows in a radiograph as a blank space. (Figs. 8, 9.) H. Drinkwatbr 29 In adult life this piece of gristle becomes ossified, and with the shaft and epiphysis forms one bone. Fig. 9 shows the epiphysis at the base of the first phalanx and one at the base of the third but the second phalanx is seen to be without any epiphysis except in the case of the middle finger. This absence of epiphysis accounts for a good deal of the shortening of the finger, but not for the whole of it ; for it is obvious that the shaft of the bone is of less than normal length and the first and third phalanges are also slightly shorter than they should be. Fig. 8. Outline of bones (not fully ossified) of brachydactylous finger of a youth. 1. First phalanx with epiphysis (ep.) at base. 2. Second phalanx without epiphysis. 3. Terminal phalanx with epiphysis (ep.). There are three factors producing the shortening of the second phalanx : (1) The slight shortness of the shaft of the bone. (2) The absence of the epiphysis. These have already been referred to, but (3) There is still another factor and to this is perhaps attribu- table the chief share in the production of the shortening. I have already drawn attention to the cartilage or gristle between the shaft and the epiphysis. So long as this cartilage remains the bone can and does increase in length with the growth of the individual but when it has become ossified, then no further growth, in length, of the 30 Minor-Brachydactyly Fig. 9. Haud of boy showing absence of epiphysis at base of second phalanges except in the middle finger and thumb (natural size). H. Drinkwatbr 31 bone can take place at this point. Now this la3'ei- of cartilage does not become ossified in the average individual until about the twentieth year, so that until that age the phalanx can and does increase in length. If however ossification occur.s prematurely, then the growth of the bone will be arrested and a permanent shortening will be the result. This is exactly what has happened in this family especially in the first and little fingers. In Fig. 5 the second phalanx is seen to be short in all the four fingers. This is the hand of a woman (No. 9). Fig. 10 shows the hand of her son (aet. 14). Here there is no sign of the epiphysis of the second phalanx except in the middle finger where it has already united to the shaft. In the other fingers it has never been present or has united during infancy. The abnormality in this bo}' will therefore be an almost exact repetition of the mother's. These cases represent the extreme type of deformity in this family. Fig. 11 .shows a modification of this type in the adult. It is the hand of No. 12. The second phalanx is seen to be much more shortened in the index and little fingers than in the middle and ring fingers. Why is this? I think the explanation is furnished by the radiograph (Fig. 12), which shows the hand of her daughter aged 8. In this girl's hand there is an apparent absence of the epiphysis in the fourth finger, and in the index finger ankylosis has already occurred, whilst in the middle and ring fingers the epiphysis is still separated by cartilage. When growth is complete this hand will be like the mother's with the second phalanx much shorter in the first and fourth fingers than in the second and third. In another child of No. 12 aged 2 years the ossification of the cartilage has already occurred in the first finger (Fig. 13). The third factor concerned in the production of shortening of the middle phalanx is, therefore, premature ossification of the cartilage intervening between the shaft of the bone and its epiphysis. The essential feature of the abnormality in No. 1 family was stated to be "an absence of the epiphysis at the base of the second phalanx" with subsequent ankylosis of the second to the first phalanx, so that we have in the present family an abnormality which is essentiall)' the same developmentally but stopping short of ankylosis. The second phalanx in the middle finger is less affected than in the others and this was also a characteristic of No. 1 famil3^ 32 Minor-BracJnjdactyhi The second phalanx of the thumb differs in the two families : in No. 1 the basal epiphysis was absent but in this family it is present. The abnormality in the toes appears to be practically identical in the two families for in both there is an absence of the middle phalanx- Fig. 10. Hand of boy ( x J). No. 18 in chart. epiphysis and in the adults there is ankylosis of the second and terminal phalanx in the small toes. In each abnormal individual both hands and both feet are symmetrically affected, so that, in this respect, the peculiarity is as extensive as in No. 1 famil}'. H. Drinkwater % ^"OOM**-' Fig. 11. Hand of Woman (slightly reduced). Nj, 12 in cliirt. Journ. o£ Gen. ii Mi iior-Brachydai-tyhi Fip. 12. Hand of girl, aged 8. (Natural sizi zc.) H. Drinkwater oo 3—2 2(i Minor- Brachydactijly Fig. 14 is taken t'rom an adult member of this niinor-brachydactylous family. The measurements so far as they have been made are given in the following table. Measurements of Ahnormals. in Chart Age Middle Finger Hand Heigljt 5 81 2| inches 6i inches 62 inches 7 — 2| i> e" „ 59 „ 8 33 2| ,, H 604 .. 9 54 — — 10 51 3| ,, 7 „ 62 ,, 12 40 2i J, 6i „ • 60 „ 13 — n )) 6J „ 57 „ 14 — n ,, fif „ 583 „ 16 33 — — — 17 17 — — 571 M 18 15 — — 54| „ 19 8 — — — 20 2 — — — 21 14 21 )» 5 „ 544 „ 22 5 2i ,, 41 ,. 471 .. Scanty as the figures are they indicate very decidedly two charac- teristics, viz. : (1) The shortness of the fingers. (2) The shortness of stature. (1) The average length of the middle finger of the seven adults (male and female) is 2"57 inches which is fully three-quarters of an inch less than the normal. The shortness of the hand of the boy (No. 21) is shown not only by the photograph (Fig. 2) but by comparison with the hands of two of his younger brothers as shown in the following table : Age Finger Hand No. 21 (abnormal) 14 Brother (normal) 12 7 2;^ inches 2| „ 2i „ 5 inches 6 „ 51 „ (2) The shortness of stature is well shown by the photograph of No. 21 (aged 14) and his younger brother (aged 12) who is normal and the taller of the two. (Fig. 15.) The average stature of the four women Nos. 7, 12, 13 and 14 is .58'6 inches and of the three men Nos. 5, 8 and 10, 615 inches. H. Drink WATER 37 Fi^'. 14. Foot ot ailult showing abortive middle phalanx. (Natural size.) 38 Mmov-Brach]idad]ihj Fig. 15. Photograph of two brothers. The shorter boy is aKetl 14, and is Brachydactylous. The taller is a^'el 12 and is normal. H. Drinkwatbr 39 Now these figures are very remarkable from their close approximation to the same measurements in No. 1 family where they were respectively 58^ and 61 inches. The women are therefore about 4| inches and the men about S inches below the normal height. It is the general opinion that the abnormals have better health than their normal relatives. The abnormals are slightly more prolific than the normals though the numbers are too small to enable one to draw conclusions on this point. Increased fecundity was a marked feature of No. 1 family. In both families a much larger proportion of normals have remained unmarried. The schoolmistress stated that the parents of the boy (No. 21) are cousins but such is not the case and I could not hear of any intermarrying in the family. Mendelism. This family illustrates certain Mendelian rules : (1) There is perfect segregation. The abnormality is either not transmitted or it is transmitted fully : i.e. so as to involve the digits of both hands and both feet. (2) The abnormality is transmitted only by the abnormals and never by the normals, so that all the descendants of normals are normal. (3) The offspring of parents, OHe of whom is abnormal (= dominant) the other normal (= recessive), should theoretically show 50 "7„ of each type. The descendants, in this family, counting only those whose type is known for certain, amount to 47, and of these 21 are abnormal : i.e. 21 abnormals to 26 normals giving 446 insteail of the theoretical But this percentage is not to be regarded as positively correct. It is certain that it is as high as this, but not at all certain that it does not more closely approximate to the theoretical number. When I first interviewed the woman No. 9 in the chart she informed me that of her ten children only one had short fingers like her own, viz. her eldest daughter (No. 16) and a casual inspection would have confirmed her statement. The shortening is so incon- spicuous that in some of the children it is only detected by flexing the finger, and then the shortened middle plialanx is noticeable but 40 Minor-Brachydactyly not otherwise. By this means I was able to show her that her two youngest children's hands were brachydactylous and this is confirmed by the radiographs. In adult life the shortness of the hand is conspicuous enough and cannot be overlooked, but this is not so during childhood, so that it is possible that of the few children whom I could not see and who were declared to be normal, one or two may be of the abnormal type, and if so would make the percentage of abnormals still more closely approxi- mate to the theoretical figure. I have been able to obtain radiographs of the hands of Nos. 9, 12, 14, 17, 18, 19, 20, 21 and 22 and of the feet of all the same except No. 9. [Figure 4 is reproduced by kind permission of the Royal Society of Edinburgh.] The expenses in connection with this investigation have been defrayed by a grant made by the University of Edinburgh from the Earl of Moray Endowment for the promotion of original research. A CKITICAL EXAMINATION OF RECENT STUDIES ON COLOUR INHERITANCE IN HORSES. By a. H. STURTEVANT, Columbia Universiti/. About a year ago I published a paper on the inheritance of colour in the American Harness Horsed I concluded that the colour of these horses is, in general, determined by five factors : C (chestnut or yellow), hypostatic to the others and always present ; H (Hurst's factor or black) ; B (bay), epistatic to H ; R (roan), and G (gray). There were at that time two other papers on colour inheritance in horses with which I was not acquainted. The first, by Dr E. H. Harper=, was not written from a Mendelian standpoint, but contained confirmatory evidence for my views about black and gray. The second, by Prof. James Wilson^ had already covered most of the points which I brought out, and some others as well, although Wilson does not seem to have had a very clear idea of the factors concerned, as is shown by his attempt to represent the gametic constitution of his stallions by only two symbols each. Tliere is one point on which we reached quite different conclusions — namely, the position of brown, which I shall discuss later. These three papers deal with five different breeds, the English Thoroughbreds and Shires and Scotch Clydesdales being treated by Wilson, the French Percherons by Harper, and the American Harness Horses by myself. It is my purpose in the present paper to compare and combine the contents of these three contributions. Wilson and I agree that chestnut stands at the bottom of the scale, and neither of us found any horse lacking the factor for it. 1 Biol. Bull. XIX. No. 3, August 1910, p. 204. = Biol. Bull. IX. No. 5, October 190-5, p. 26.5. 3 Sclent. Pro£. Royal Dublin Soc. 12 (N. S.). No. 28, 1910. 4-2 Colour Iiiliiritance in Horses The nexrt factor, that for black, H, was discovered and correctly interpreted by Hurst'. Wilson's statistics show that this factor is carried by bays, browns, and blacks, though he gives no factorial interpretation of his results. The figures for matings of chestnuts, i.e., of li h individuals, are as follows: — Colour of Foals Breed Chestnut Black Brown Bay Authority Thoroughbred 1095 9 (liay or brown) Hurst Shire 44 1 1 5 Wilson Trotter 69 0 0 0 Sturtevant Total 1208 Ifi not chestnuts Hurst also gives five other authorities for the statement that chestnut breeds true, in various other breeds of horse.s. Hurst, Wilson, and I all found a good many sires producing no chestnut foals, i.e., homozygous for H. These are blacks, bays, browns, grays, and roans. The total foals from heterozygous sires and chestnut mares is as follows : — Breed Thoroughbred Clydesdale ... Trotter Cliestnut Not Chestnut Authority 347 355 Hurst 3 2 Wilson 65 56 Sturtevant Total 415 413 My next factor was B, or bay, and I considered brown as being usually a heterozygous form {GHBh), although I also realised that horses with the above constitution are often bays. I found what I thought was a brown stallion with the formula GHBB, but this horse (Prodigal) as I have since found, is recorded in the later volumes of WalUices Year Book (my principal authority) as a bay. The change was made after he had become famous as a sire, and is therefore probably correct. I was inclined to explain the four browns recorded as produced by two black parents by supposing that some GHbb horses are browns. I now believe these four cases to be errors in the record, this opinion being based on Wilson's and Harper's figures for matings of blacks to blacks (see below). Wilson reached a quite different conclusion. He regards bay and brown as dominant to black. His idea as to the relation between bay and brown is shown by the following passage. " The relative positions ' Pror. Hoi/iil Sof. 77 B, I'.HJIl, p. 388. A. H. 8TURTEVANT 43 Black X Black Colour of Foals Breed Black Bay Brown chestnut Authority Percheron . . . 49 (2 not black) Harper Shire 39 3 0 2 Wilson Clydesdale ... 36 0 2 0 Wilson Trotter 34 2 4 2 Sturtevant Total 158 Black X Bay Thoroughljied 1 33 27 11 Wilson Sliire 39 125 43 19 Wilson Trotter 16 48 31 7 Stuitevant Clydesdale .40 104 67 7 Wilson Total 96 310 168 47 Black X Brown Thoroughbied 8 12 20 0 Wilson Shire 39 19 36 4 Wilson Clydesdale ... 61 34 106 1 Wilson Trotter 11 5 9 1 Sturtevant Total 119 Bay 70 X Bay 171 6 Thoroughbred 1 1295 125 270 Wilson Shire 13 287 18 28 Wilson Clydesdale 6 243 59 5 Wilson Trotter 1 46 3 9 Sturtevant Total 21 1871 205 312 Bay X Brown Thoroughbred 10 744 365 123 Wilson Shire 23 133 56 5 Wilson Clydesdale ... 25 206 254 5 Wilson Trotter 9 81 31 8 Sturtevant Total 67 1164 706 141 Brown x Brown Thoroughbred 6 78 114 11 Wilson Shire 7 20 27 2 Wilson Clydesdale ... 32 34 165 0 Wilson Trotter 5 7 7 0 Sturtevant Total 50 139 313 13 44 Colour Inheritance in Horses of bay and brown remain to be settled ; and although there is evidence in favour of brown being dominant to bay, this conclusion is not clearly established. It must be remembered these are the colours breeders have the greatest difficulty in discriminating; and errors affect sires and dams and foals. In regard to sires it has been po.ssible to correct the registered colours in several cases ; and while every correction has increased the evidence in favour of brown being dominant, it is still possible that there may be other explanations, as, for instance, that bay is a diluted brown." I shall first give the figures bearing on this question, and then discuss their significance in connection with the two views given above. My hypothesis that brown is a heterozygous colour was based upon two facts. In the first place, I am unable to see any very sharp line between bay and brown. Wilson evidently thinks the two colours are distinct, but I can find no definite statement as to what the difference is, although he discusses the distinction between the various colours at some length. Secondly, all the browns from which I could find any fair number of foals produced some blacks, with the exception of the stallion Prodigal, which, as I have explained above, now turns out to be a bay. I have found 1.5 such brown sii-es producing black foals. In Wilson's tables appear five brown and one doubtful bay or brown Clydesdale sires, all of which have a fair number of black foals. There are also five brown Thoroughbreds. Two of these sired no blacks among 93 and 95 foals, respectively, though each has a foal recorded as " brown or black." Ladas has one black and one black or brown among 97 foals, Desmond three black and two brown or black among 48 foals, and Wolf's Crag seven black and one brown or black among 95 foals. Here we meet an interesting fact — the extreme scarcity of blacks among English Thoroughbreds. Wilson believes that most, if not all, the recorded blacks are really browns, and was not able to find a genuine black stallion. The Desmond mentioned above is recorded as a black, but Wilson ascertained that he is really a dark brown, and the same was found to be true of all the mares recorded as black of which he could get definite and reliable informa- tion. Only about 1 °/^ of these Thoroughbreds are recorded as blacks. Of course by my hypothesis it would be hard to explain how there could be about 14°/, browns and only 1 % blacks. However, I shall not try to explain this, as the hypothesis is pretty well disproved by the result of mating browns together. If it were correct such matings should produce 25 7o blacks, 25 7„ bays, and 50 7o bays and browns. A. H. Sturtevant 45 As is shown above they do produce a trifle less than 10 "/^ blacks. I am still convinced, however, that there is something in my original hypothesis. It could scarcely be a coincidence that twenty brown sires should be heterozygous and none homozygous, if we except the Thoroughbreds. Among the latter I believe that Wolf's Crag, Desmond, and perhaps Ladas are heterozygous, for it is evident that in a population containing only 1 °/^ recessives there would not be a large proportion of heterozygous mares, and a heterozygous stallion would of course not produce recessives when mated to pure dominant mares. Again, it will be noticed in the tables above that, excluding chestnut foals, black mated to bay gives only 1 6 % black foals, while black mated to brown gives 33 7o. or twice as many. And while brown to brown gives only 10°/„ blacks, bay to bay gives still fewer — only about 1 %, or 3 7o> if '^'^^ omit the Thoroughbreds, of which the table illustrating this class has a relatively large proportion. According to Wilson's hypothesis that brown is dominant to bay, bay to bay should produce no browns. This would require the further hypothesis that the 205 browns recorded from such matings are errors in description, which certainly does not seem to me to be probable. Again, there should be some brown sires producing no bay foals, but as a matter of fact all of the 25 brown sires found produce a large proportion of bays. I have, in fact, never yet found a sire which did not produce bays. Finally, as stated above, I am unable to agree with Wilson that bay and brown can be satisfactorily separated. I base this upon my own observation, upon the frequent changes from bay to brown and vice versa which he mentions finding in the Clydesdale records, and the similar changes which I have observed among Harness Horse records, and upon the frequent recording of English Thorough- breds as " bay or brown." My conclusions, then, are that brown and bay are not distinct, brown being merely a dark bay, and that brown is more often GHBh than GHBB, and never CHhh. It would be interesting to know whether or not the heterozygous bays are darker than the homozygous ones. In regard to gray there is no great difficulty. I thought when I published my first contribution that I had a non-conformable case, where two brothers not gray were siring about 50 % E^^J foals. One of these, Dispute, I now know to have been wrongly recorded, as his owner, Mr John Taylor, and another breeder, Mr W. B. Gill, both write me that he is a gray. The supposition therefore is that his brother was also a gray, though I have been unable to verify this. But if he 46 Colour Inheritance in Horses was, then the whole family works out exactly according to expectation. The produce from one gray parent and one not gray is as follows : Breed tJray Foals Not " Cfl CO IC OS T-( IM CC 00 -*< 'M :C X «D CT CI C5 CO CC 00 O C"! i-H 1-1 ,-t o 10 CO »o 0 10 0; 01 00 CO 0 CD CO 00 CD 8 g 00 3 ■X X CD 05 0 S X 0 -J 0 i-H i-H 0 0 0 '"' 0 0 0 0 0 0 '"' 0 r-t iH iH 1-1 Si 05 CO .— 1 00 co CO >-i 0 C>1 Cf5 00 01 CO 2 01 Oi ,— c CD 0 CO ^1 CD c^ 'ft* ;^ CD 0 rH CO CD « 0- -t* -t* CO CD "Tfl ■M CO Ol CD .-J ■^ 0 t^ <7^ 10 CO CD W3 ITS 10 § io tr- io s IC CO >o en 10 10 g CO 10 1 5" .-1 CO 1— 1 CO 1—1 - 10 CI 6 CO <— 1 0 1— 1 10 CO 0 CD X CO 0 8 CO 1— I 1 1 rH a; 10 CO 00 CD 5 -* 0 CO -*< 00 CO .—1 >o 0 X 1—1 CO 1 1 OS rH CO r-l •-a g 10 01 00 •-* OD CO CD CO CO 0 rH 05 OS CD Gi 10 CO I-H CI 2 in CO 1 1 CD »o rH tn c. no 0 CQ 0 a. >, 0 a ^- a a O H - > > ^ 3 a >^ K « 3 ^ > ^^ R. H. CoMPTON 63 there were 228 more RH than LH individuals : and among 2881 seedlings from the even rows there were 243 more LH than RH individuals. There can be no doubt that so large a divergence from the mean ratio unity is significant : especially as in the majority of the Maize cobs considered separately a similar result was obtained. Further, individual rows of seed gave the same excess of LH or RH offspring according as tliey were even or odd. There is no need to give the data for all the cobs : but one set of results will be quoted in full as an example of the phenomena encountered. The numbers shown in Table VI were yielded by cob XIII, and may be taken as typical of those given by the others \ TABLE VI. Number of Offspring Number of Row Odd Rows Even Rows LH RR LU JJfl 1 14 19 — — 2 — — 14 16 3 7 25 — — 4 — — 18 14 5 16 16 — — 6 — — 20 11 7 9 22 — — 8 — — 20 12 9 13 14 — — 10 — — 19 9 11 15 13 — — 12 — — 15 11 13 13 9 — — 14 — — 15 13 15 8 21 — — 16 — — 16 13 Total 95 139 137 99 The reference numbers of the rows in the first column are arbitrary: No. 1 was a casually selected odd row, No. 2 the even row of the same pair, and so on all round the cob in the direction of the arrow in Diagram 3. The results for even and odd rows are displayed in different columns for the sake of clearness. It will be seen that five of the eight odd rows gave an excess of RH seedlings, and that seven of 1 In this particular cob the seeds of each row were sown in order of position, with the object of determining whether there was any further regularity in the distribution of rights and lefts over its surface : no such pattern, however, could be detected. 64 Studji of Right- and Left- Handedness the eight evea rows gave an excess of LB. seedlings. There are alto- gether three exceptional rows in which the proportion of rights and lefts are reversed, and one in which LHjRU =\. Such exceptions occur in all the cobs studied, both in even and in odd rows : they are probably to be attributed to tiuctuating variability of the same kind as was found in the ratios for ears of two-rowed Barley, and represented by normal curves'. It must be noticed that exceptions to the general rule are not lacking in individual cobs, as will be seen on reference to Table V. Cob VII shows a ratio of very near equality for both odd and even rows. Cob XIV shows a ratio of about \% not only for the even rows (where it is normal), but for the odd rows as well : a result which may be compared with that obtained in Barley. Cob XI is the most striking exception, for here the odd rows gave a definite excess of lefts and the even rows a similar excess of rights : this being the exact reverse of the usual results. Another cob, doubtfully of the same variety as cob XI — viz. cob XV — also gave somewhat abnormal i-esults, so that it is possible that different varieties of Maize may behave in different ways^ No further cobs of the same varieties as VII and XIV could be procured. But despite exceptions, both in the offspring of individual rows aud of single cobs, the general conclusion appears to be justified that odd rows on the Maize cob give an excess of right-handed, aud even rows an excess of left-handed, offspring. It remains to find a reason for this behaviour. It was thought possible that the position of the ovule with respect to its neighbours, and the consequent differences in pressure which would be experienced by ovules according as they were produced in odd or even rows, might cause differences in the shape of the early environment of the embryo which would be to some extent reflected in the mode of folding of its first leaf This hypothesis was tested by the following experiment. A cob (XVII) was chosen whose rows were considerably distorted, and whose seeds consequently showed much variety of shape. The seeds were divided into three lots according to the relative thickness of the two lateral edges: looking at the outer end of the seed with the embryo uppermost it was placed in class (a) if the LH edge was narrower than the RH, class (c) if the i-everse was the case, or class (b) if it could not be definitely included among (a) 1 Compton, 1910, p. 501. ^ Further experiments are being made with this variety of Maize. E. H. CoMPTON 65 or (c). (See Diagram 4 in which one is supposed to be looking at the distal end of the seed in situ, the shaded semilunar area repre- senting the position of the embryo.) The three classes were sown separately and the ofifspring counted, the results being as follows : — TABLE 1 VII. Offspring Class LB RB a 38 37 b 40 39 c 33 33 Total 111 109 Thus the three classes of seeds gave precisely similar results, the ratio being equality in each case — i.e. the same ratio as given by the whole number of Maize seeds studied. Diagram 4. Though this experiment failed to give a positive result, it cannot be considered as conclusive evidence against the theory it was designed to test. It seems probable a priori that a variation in symmetry of the seedling should be produced by asymmetry of the space within which the embryo develops, and that this asymmetry should be produced by the pressure of neighbouring seeds: in fact that asymmetry in the parent should directly produce asymmetry in the offspring'. Several examples are indeed given by Macloskie- showing that the seeds from opposite sides of a bilateral fruit (silicle or legume) are " antidromic " — a word which he uses very broadly to cover many different kinds of asymmetry. ' An essentially similar hypothesis has been suggested by van Biervliet to account for the apparent inheritance of human right- and left-handedness (see footnote to p. 68). He remarks, " Nous savons que la femme droiti^re a la hanche di'oite plus developp^e, la gauchere la hanche plus forte a gauche. La structm'e du bassin ue pourrait-elle influer BUT la position de I'embryon ? ou du moins favoriser le developpement preponderant du c6t6 gauche?" ("L'homme droite et I'homme gauche," Revue philosophique de la France et de VEtranger, XLvn. p. 385, 1899). The existence of left-handedness among the children of a LH father and a RH mother, as recorded by Jordan, tends to cast doubt on this hypothesis but does not destroy it altogether. The collection of a greater number of pedigrees is the most obvious method of solving the problem. 2 Bull. Torrey Bot. Club, xxn. p. 879, 1895. Journ. of Gen. ii S 66 Study of RUjht- and Left- Handedness An alternative explanation would be possible on the basis of a hypothesis of a somatic segregation of characters' if it be assumed (i) that the characters of right- and left-handedness are represented in the gametes, and (ii) that odd rows tend to produce an excess of female gametes bearing right-handedness, even rows an excess of those bearing the character for left-handedness. (The male gametes may be left out of account when considering large numbers, for pollination is anemo- philous and promiscuous.) The alternative explanations are (i) that the influence determining the fold of the first leaf is of a feeble nature and acts upon the gamete or embryo, which itself has no special inclination to become right- or left-handed, but must choose one or the other : or (ii) that the female gametes are definitely right- or left-handed, and that a certain amount of somatic segregation occurs. In order to maintain this latter alternative explanation it would be necessary to show that right- and left-handedness in Maize are in some way hereditary characters. The statistics give strong evidence that this is not the case. Almost all the 17 Maize cobs studied gave ratios between lefts and rights very nearly alike (p. 62) : but it is almost inconceivable that in every case the parent plant should have had the same direction of fold in its first leaf. It is evident that in different cereals there are tendencies to produce different ratios ; Barley for instance gave a very different result from Oats : and it is possible that the inverse ratios given by Maize cob XI point to some .similar divergencies between different varieties of Maize. But the fact that different plants give different ratios and that (in the case of Barley at least) the ratio is constant for successive generations does not imply that the characters of right- and left-handedness them- selves are hereditary. We may therefore conclude that there is no evidence for the inheritance of the direction of fold in the first leaf of Maize : and this conclusion harmonises with the similar one previously reached in the case of Barley. A further argument against the second alternative explanation is the fact that, though much sought, up to the present no direct proof of .somatic segregation affecting gametes of the same sex has been obtained, however probable the existence of such a phenomenon may appear. ' See W. Batesou and E. C. Punnett, "On the Inter-relations of Genetic Factors." Proc. Roy. Soc. B, Vol. Lxxxiv. p. 6, 1911. " On Gametic Series involving Reduplication of certain Terms," Verh. d. naturf. I'er. inllrilim, Bd. xLix. 1911 and JoiiVH. Ge)iet. Vol. 1. 1911. R. H. CoMPTON 67 It seems therefore almost impossible to maintain the hypothesis of somatic segregation of right- and left-handedness in Maize: and despite the negative result of the single experiment on the subject, I incline to embrace the first explanation proposed, viz., that the difference in offspring between odd and even rows is due to the direct influence of spatial relationships on the developing embryo. In two-rowed Barley no such dependence upon position was found : it may be suggested that the difference in the case of Maize is due to the close packing together of adjacent rows of seeds ; for in two-rowed Barley the individual seeds develop without lateral pressure from neighbouring rows such as they experience in Maize. Genetic Spirals. It is not proposed at present to enter fully into the question of genetic spirals from the point of view of ratios and heredity : experi- ments are in progress, and it is hoped to publish a paper on this subject at some future date. Meanwhile it is interesting to remark that the ratio LHjRE, for genetic spirals also, diverges from equality in a more or less marked degree in the cases investigated. Bonnet' found 43 RH and 30 LH stems among a collection of 73 plants of Chicory. Out of 458 plants oi Lepidium sativum I found 241 LH and 217 RH. Not only is there a divergence from equality in the case of different plants, but on one and the same plant there may be a considerable excess of branches showing one spiral over those showing the reverse one. Valuable data were obtained^ by Dr A. H. Church and Mr E. G. Broome with respect to the genetic spiral of certain individuals of different species of Pines : the following numbers were recorded : — TABLE VIII. Number Per cent. Per cent. Year of cones LH Jiif 1900 100 41 59 1901 1000 46-4 53-6 1902 500 46-0 54-0 1900- -02 1600 45-94 54-06 1900 100 47 53 1900 100 68 32 1901 400 71 39 1902 600 69-16 30-83 1900- -02 1100 69-82 30-18 lilles, p. 179, ] L754. of Plnillotaxis to tlecliaiHca if Lmvs, pp . 92, 351, London, Tree P. austriaca ,, Average P. pumilio P. laricio ,, Average 1 Recherches snr Vusage des '- A. H. Church, The Relat 1904. 5—2 68 Study of Right- and Left- Handedness These results are very striking, and as Church remarks, "The element of chance appears quite out of the question " in the case of P. laricio. It may be suggested that perhaps differences in conditions (sunlight, prevailing winds, etc.) between opposite sides of the tree may have caused an excess of cones to arise towards one side : and that, since the genetic spiral of a lateral branch depends on its mode of insertion, this might be the cause of the excess of one kind of spiral among the cones. At present, however, it is impossible to decide whether this accounts for the phenomena, or whether there is a definite tendency in the apical meristem to produce a genetic spiral of one direction rather than the other. Conclusions. The present paper deals with the dimorphism found in certain Gramineae in respect of the mode of folding of the first leaf of the young plant. It is in part a continuation of a previous paper (cited above) to which reference should be made for an explanation of the conventions used in describing the phenomena, and for a summary of the literature of the genetics of right- and left-handedness in general'. ' Further references to works on the genetics of right- and left-handedness may be inserted here. H. E. Jordan ("The Inheritance of Left-Handedness," American Breeders'' Magazine, Vol. II. pp. 19, 113 : 1911) gives a number of human pedigrees which show that functional left-handedness is hereditary, in certain cases apparently in conformity with a simple Mendelian scheme. The most remarkable human pedigree on record is perhaps tliat given by Aim6 Per6 (Les courhures lateralcs normales du rachis hmnain, Toulouse, 1900, p. 71 : quoted by D. J. Cunningham, "Right-Handedness and Left-Brainedness." Journ, Anthropol. Inst, xxxii. p. 273, 1902). In this family no fewer than twenty-six left-handed individuals are recorded : the marriage of a LH ? x RH . P. nearer D.P. not conspicuously petiolate Conspicuous net- Network of veins Some veins sUghtly A few veins raised work of large raised above gene- raised above gene- slightly above veins raised a- ral surface ral surface, hardly general surface, bove general sur- forming a net- not forming net- face work work Large, transversely Some large, trans- Very few large, trans- No large, trans- running veins versely running versely running versely running veins veins veins Crinkled, coarsely crenate Smaller than D.G. Not crinkled, coarsely crenate- serrate Intermediate Not crinkled, coarsely den- tate, teeth prolonged into points Intermediate Not crinkled, ser- rate Larger than D. P. ■2 mm. •2 mm. •33 mm. 76 Sjyecies Hybrids of Digitalis {D.G. X D.P.) is a greenish-cream (very much ligliter than in D.G.) with pale rose flush above, also with spots (Plate IV, fig. 7). In neither hybrid are the brown markings characteristic of D.O. apparent. 5. The shapes of the corolla tubes in the hybrids also show a preponderant influence of the female parent (see Plate IV). 6. The anthers of all e.xcept D.G. have dark purple .spots; the spots in the hybrids, however, are smaller and less numerous than in D.P. Calyx. In all the four forms of Digitalis under consideration the sepals are of three sizes ; the upper being the smallest, the two lower laterals largest, and the two upper laterals intermediate in size. 7. Comparing now corresponding sepals of these plants : those of D.P. are large, broad and ovate and have numerous, conspicuous veins raised above the surface (text-fig. 5) : those of the other species D.G. ai'e small and narrow with few, very inconspicuous veins not raised above the surface, lateral branchings being quite invisible in the fresh green sepals (text-fig. 6). The sepals of the two hybrids are intermediate in every particular, but differ from one another in that {D.P. x D.G.) (text-fig. 7) is nearer the D.P. type as regards shape and veiuing than is {D.G. x D.P.) (text- fig. 8). In this latter, the sepals tend to be almost the same width throughout their length, instead of narrowing gradually towards their bases. 8. The way in which the sepals of any one flower are united is also characteristic : in D.P. and {D.P. x D.G.) the members of the calyx overlap one another in the fully opened flower (text-figs. 1 and 3), while in D.G. and {D.G. x D.P.) gaps occur between them (text-figs. 2 and 4). 9. The nature of the multicellular hairs on the calyces is also worth notice. In D.P. the hairs are long, slender and of two kinds, viz. with pointed end-cells and rounded end-cells (text- figs. 17 and IS). In D.G. the hairs are all of one kind — short, stout and with rounded end-cells (text-fig. 19). In the hybrids the hairs are intermediate in size and all have rounded end-cells (text-figs. 20 and 21), there being no very noticeable difference between the reciprocals. This distinction in size and structure of the hairs was not found to hold in the case of the ordinary foliage leaves, on which the hairs are of different character and common to all four types of plants. W. Neilson Jones 77 CO lO CO ir5 CO 00 a. O CM Q 78 Species Hyhrids of Digitalis DPx DG 20 DG ■ DP 21 -I Figs. 17—21. 10. Fruits. The fruits of D.P. are markedly curved lougitudiually and have furrows running along the sides only (text-figs. 9 and 13) : those of D.O. are almost cylindrical and have furrows running not only along the sides but also top and bottom, as is evident in the cross- section of the ovary (text-figs. 10 and 14). The fruits of the hybrids were too imperfect to allow any very definite conclusions to be drawn as to their shapes had they swollen properly ; but in {D.P. x D.G.) the upper and lower furrows are practically invisible on the outside, but are indicated on the in.side wall of the capsule (text-figs. 11 and 15); while in {D.G. X D.P.) these furrows are also more or less observable on the outside (text-figs. 12 and 16). 11. Although these general characters of the hybrid capsules are admittedly unsatisfactory for the reason given above, the nectaries are more completely developed and easy of comparison. Thus the nectary in D.P. is a rather inconspicuous, narrow band of tissue at the base of the capsule and forms part of the general curve of this latter (text- fig. 9 n). The nectary of D.G., on the other hand, is rendered conspicuous by its breadth and by not forming part of the general curve of the capsule (text-fig. 10 n). W. Neilson Jones 79 The nectaries of the hybrids are intermediate in character between those of the two species, but differ from one another in inclining markedly towards the respective female parents as to size and shape in relation to the capsule (text-figs. 11 and 12). The differences between the four plants is not confined to the flower parts, as the leaf characters alone are sufficiently distinct to enable one easily to assign any plant to one of the four classes. 12. Leaves. The leaves of D.P. are large and broad (the radicle ones being as much as 30 cm. long and 10 cm. broad), ovate in shape and, with the exception of those some way up the flowering axis, with a well-marked petiole. The leaves of D.G. are never as large as the above (the larger ones are about 18 cm. long and 3 cm. broad) and much more linear in shape. They taper gradually to a rather shai'p apex instead of being obtuse as in D.P., and there is no demarcation between lamina and petiole, the leaf gradually narrowing towards its base which is much broader than in D.P. The leaves of the hybrids are intermediate in size and shape : those of {D.P. X D.G.), however, resemble more closely the leaves of D.P., while the leaves of {D.G. x D.P.) are almost indistinguishable from D.G. as regards shape. The above differences in leaf-form are most noticeable in the radicle leaves. 13. Much more definite than the differences in shape are the differences in texture and surface of the leaves of the four types. Photographs of the under sides of the radicle leaves of D.P., D.G., {D.P. X D.G.), and {D.G. x D.P.) are shown in Plate V. In D.G. (Plate V, fig. 9) it will be seen, that while the midrib and some of the larger longitudinally running veins ai'e raised somewhat above the general surface of the leaf, the smaller veins are quite invisible. In D.P. (Plate V, fig. 8), however, all but the very smallest veins stand up prominently above the surface in the form of a network covering the entire under surface of the leaf. There is a correspondiug diff'erence in the upper surfaces of these leaves ; D.G. being quite smooth except for slight depressions along the midrib and some of the larger veins, while the whole upper surface of D.P. is covered with a conspicuous network of furrows. As will be seen from figs. 10 and 11 of Plate V, the hybrids are intermediate between these two conditions, the reciprocals differing in 80 Species Hyhrids of Digitalis that each follows the maternal type. The upper surfaces of the leaves show similar peculiarities. That the above differences are due not merely to degree of pro- minence of the veins but also to a dissimilar system of venation may be seen from text-figs. 22 — 25. 25 DGxDP Figs. 22—25. These are camera lucida drawings of leaves bleached in Mayer's solution, stained in safrauin and afterwards cleared and mounted in Canada balsam. In D.P. there is a network system of large veins, whilst very fine veins fill up the meshes of this network. In D.G., on the other hand, the only large veins are the midrib and a few longi- tudinally running laterals (which are much smaller than the large veins of D.P.) — the rest of the system consisting entirely of veins all of much W. Nbilson Jones 81 the same size and considerably broader than the finest veins of D.P. The reciprocals (text-figs. 24 and 25) differ from one another in the greater resemblance to the seed-parent in each case. 14. The margins of the leaves also show well-marked characters. That of D.P. is ci n1 o ^ T3 'tI n> Xi ■73 4J n rn P^ n s XI 't-a 2 X o n - s ^O ~ o* ^ ^a i-i o *» S _sd - *Oe2 O O -^ ;2 ^ J] s 3^ S^ ^ s — =3 « e j=0 ^ s 94 Colour and Other Characters in Pigeoiin Series C and D. Black, blue, and tvhite. The third series of experiments was concerned witli the inheritance of colour only. In it two original pairings were made, G and D, a Black Fantail hen by White Fantail cock and the reciprocal cross white hen by black cock. The Black Fantails used were guaranteed of pure stock by the breeder who supplied them, all their feathers were full black except the webs of the tail feathers and primaries, which were very finely mottled with whitish, especially at the base, giving the web a greyish appearance. After a number of young had been obtained from these birds paired with White Fantails, the black cock and hen were paired together and produced two young, one of which was full black with practically no grey on the webs of the quili-feathers, the otlier black with as much grey as the parents, and four white feathers, two primaries in the left wing and two covert feathers in the right. It is possible therefore that one or both the original black parents was not pure bred. Control experiments were made with pedigree birds as described below. White Fantail Black Fantail 19 black and white (all with much white) of which F-ii 3 white and black F] ? I 1 white and blue F^i FxS ? White Fantail I F,i Fii 4 black and white 4 blue and white 1 I 7 white I I 2 white and black I 2 white 1 black and white 3 white and black Fig. 4. (Series D.) 1 blue and white 5 white The results of pairing these Black Fantails with Whites were as follows. In Series C (black $ x white c/",p. 93) 13 young were produced, all pied black and white, but of these 10 had a preponderance of white, and three of black. The birds varied considerably, but those with excess of white may be described as white fantails, generally with most of the tail feathers black with grey along the shafts, and black patches of varying size and distribution on the body and wing coverts. The three with excess of black were black birds, with scattered white L. DONCASTER 95 feathers on the body, wings and tail, and in two out of the three with the rump ahnost or quite white. In Series D (white $ x black (/) there were 7 young resembling on the whole the F^ from Series 6', but with the white and black more evenly distributed. These birds might be described as mottled or chequered with black and white, or as white thickly scattered with black feathers, with most of the primaries and rump feathers and some of the tail feathers white. After 7 young had been hatched the white hen died, and another was paired with the cock (mating Z)„), and produced 12 young'. These on the whole had more white than those of the first family, but it varied in the amount from one case iu which the bird was quite white, with the exception of a small black patch on the right side of the rump, to white birds sprinkled with black feathers on the head, body and wings, and with a number of the middle tail feathers black. It was impossible to classify these birds sharply into classes with more or less white. Pairings were made between F^ birds from both matings C and D. From C two such pairings were made both between birds with pre- ponderance of white. In one {Ga I) 13 F., young were produced, 3 white, 7 white with black patches, 2 black with white feathers (of which one had only 6 white feathers) and one ' blue ' with a good deal of white. Many of the blue (slate-grey) feathers had a trace of rusty colour, and in the left primaries and tail the feathers were white speckled with grey ; the secondaries and wing coverts of both wings and the tail feathers had dark grey tips, giving a distinct tail-bar and a suggestion of a wing-bar. In the second pairing {Ga II) between F^ birds from Series C 18 young were produced, 6 white, 4 white with black patches, .5 black with white feathers, and 3 blue and white. The blue feathers were in excess of the white, but as in the previous case the blue was not clean, but was dark and tinged with brown or rusty. In Series D three pairings were made between F-^ birds. In the first only 4 young were produced, 3 white with black patches, and one white with patches of blue. The F^ cock then died, and was replaced by another, from which pairing 15 young were raised, 7 white, 4 black with white, 4 blue and white, the white preponderating in three of the latter, and the fourth being mottled. In the third pairing between F^ from Series Z* 10 young were reared, 5 white, 3 white and black, 1 black and white, 1 blue ami white. ' These two matings are included together in Fig. 4, p. 24. 96 Colow and Other Characters in Pigeons In all the blues from Series D, as from Series G, the blue feathers were tinged with rusty brown. lu all then from F^ of Series D 29 F,, birds were reared, of wliich 12 were white, G white and black (white preponderating), 1 white and blue, 5 black and white (black preponderating) and 5 blue and white. From Series G, 31 F„ birds were produced, 9 white, 11 white and black, 7 black and white, 4 blue and white, or adding the two series together, out of a total of 60 F^ young, 21 white, 17 white and black, 1 white and blue, 12 black and white, 9 blue and white. There are several points connected with these results vvhich call for comment. First, the factor for blue is evidently introduced by the whites, but being recessive to black does not appear in F^. In F.2 almost exactly one-fourth of the coloured young are blue (9 out of 38). My results in this respect confirm those of Staples-Browne' obtained with other breeds. It is interesting that the blue of the wild rock pigeon should be recessive (hypostatic) to the more recently acquired black of the domestic breeds. Another point is the absence of extracted blacks. No fully black bird was produced in F.,, and only one with as few as 6 white feathers. The fact that the original blacks when paired together gave a black with some (4) white feathers may indicate that pure blackness is not a stable character. A third point is the excess of whites over expecta- tion (21 out of 60 where 15 would be expected). This is not a great difference in itself, but a similar excess was found in Series B above (10 out of 27), and again in some of the matings described below. It has been seen that F-^ birds with more white than black in the plumage when paired together give among their coloured offspring not only young like themselves, but also blacks with a relatively small amount of white. With the object of discovering whether this difference corresponds with a difference of constitution several pairings between such ' black with white ' birds were made. Since birds of the same generation were not available, F^ birds were crossed with F„ which were nearly similar in distribution of colour. In the first of these cro.sses (0 Ga II) an F^ from 6', black, with nearly white rump and a few scattered white feathers, vvas crossed with an F« from Ga I, black with only six white feathers. Four young were produced, one black with white, two wholly black, and one blue with no white feather. In this case therefore there were three self-coloured to one black with a few white feathers. But in a second pairing of the same kind (GGalll) of 1 Proc. Zool. Son. 1908. L. DONCASTBR 97 F^ X F^ both with excess of black, but with more white than in C Ca II, of four youug, three were white-with-black and one black-with-white. In two other matings also between black-with-white birds (G Ca II and N) white-with-black was produced. In one case where a similar mating between white-with-black birds was made (CC'al, F^ from C X F„ from Cal) 2 white-with-black and 2 black-with-white appeared. It appears then that birds with excess of black can be produced from those with excess of white, and vice versa. But the only mating.s from which pure blacks were produced were those in which two black-with- white birds were paired together (C Ca /J and GCalV). The latter of these pairings consisted of an F^ cock from mating C, paired with his own black daughter produced in the mating CCall; these two produced 1 white-with-black, 3 black-with-white and 2 black. Since these results seemed somewhat confusing, and might perhaps be partly due to the impurity of the original stock of black fantails, I obtained two well-bred black fantails from fanciers which had no white speckling on the webs and paired them with whites (K and L). In mating K (white J x black (/) two young were produced, one of which died before it was fully fledged, but it appeared to be completely black. The other was patched black and white, the patches of colour being larger than in Series C and D. The white hen then died, and on pairing the black cock with another (mating K.,), one black and white mottled young one was produced. In the converse cross (Z) one young one only was produced which was black-with-scattered white feathers, and most of the tail white. The pied F^ bird from K mated with the i^i from L gave 9 young, 4 white, 3 black-with-white, 1 black with one white tail feather and 1 blue and white, with black wing and tail- bars. The Series K and L thus differ from C and D in producing one full black -fi bird, and in producing no white-with-blacks. They differed also in that most of the black-with-white birds had the central tail feathers white, while those in the Series C and D were almost always black. The results appeared at first very perplexing, especially the absence of blacks in F.,, and the fact that black-with-whites and white-with- blacks when paired together can each produce the other. These facts indicate that two or more pairs of allelomorphs must be present, and an explanation may possibly be sought on lines similar to those suggested by Mudge with regard to the inheritance of piebaldness in Rats. If we assume that pattern depends on two pairs of characters, P for piebaldness and S for full (self) colour, each allelomorphie with its absence ( p and s), 98 Colour and Other Characters in Pigeons and that colour requires a factor C, alleloiiiorphic with its absence c, and further that S and P are neither of them completely dominant (epistatic) over the other, we get the following zygotic types, opposite each of which I put the pattern which it may be provisionally assumed to represent : SS pp CC, SS pp Cc Black SS Pp CC, SS Pp Cc Black with grey webs SS PP CC, SS PP Cc i , , , . , , .^ .. ^, „ „ ^ Black with some white leathers Ss Pp CC \ Ss PP CC, Ss Pp Cc Black with white Ss PP Cc aud all combi- j nations containing P \ White with black and C but not S ) That is to say, birds homozygous for S are black, with or witliout grey webs or very few white feathers according to whether P is present or absent. Birds heterozygous for S but containing P are in general black with white, but if homozygous for P and hetei'ozygous for S (Ss PP Cc) they may have preponderance of white. Birds without S but containing P and C are white with black. If this scheme at all approaches the truth it explains (1) the absence of whites in five matiugs (C 6'a //, C Ca III, G CalV, N, and Cb) made between birds witli excess of colour over white (18 coloured, no white). (2) The excess of whites in families where they occur is also explained if it is assumed that a bird is white which contains C but not S nor P (ss pp CC, ss pp Cc). If this is so, such a bird cros.sed with a white containing S or P but not C, should give coloured offspring. I have not been able to test this suggestion, but Staples-Browne in crossing a White Fantail with a White Tumbler got a coloured F^. His suggestion is that the Fantail was a dominant white, but the explanation here suggested would lead to the same result. In conclusion, it should be mentioned that there was no evidence in my experiments that the two young hatched from the same pair of eggs are more often alike than young from the same parents out of different nests. ON HETEROCHROMIA IRIDIS IN MAN AND ANIMALS FROM THE GENETIC POINT OF VIEW. By C. J. BOND, F.R.C.S. CONTENTS. PAGE Part I. Irregularity of eye colour pattern in Man and Animals .... 99 In Man 102 In Eabbits Ill In Pigeons 112 In Cats 116 Association between eye colour pattern and skin or coat colour pattern ........... 117 Hair pattern in man 121 Part II. Irregular eye colour pattern and the constitution of gametic factors . 122 Bibliography 128 PART I.. Irregularity of Eye Colour Pattern in Man and Animals. It has been known for a long time that iu a certain proportion of the population the eyes of one and the same individual are of a different colour sufficiently marked to attract attention. In earlier references to heterochromia attention was chiefly directed to the frequent association of this condition of unequal pigmentation of the iris with diseased conditions, such as glaucoma, cataract, cyclitis, and corneal opacities, generally in the lighter coloured eye. Thus Sir J. Hutchinson (1) in 1869 reported three cases with imperfect vision in the blue eye. Marcus Gunn(2) and Sym(2a) in 1889, and Malgat (3) note the association with cataract in the lighter eye. 100 On Heterochromia Iridis in Man and Animals Fuchs(4) in 1906 reported 38 cases, of which a large proportion suffered from cataract aud a considerable number from opacities of cornea or vitreous. Anton Lvitz(5) after au exhaustive study of the subject of hetero- chromia also corroborates the frequent recurrence of diseased conditions in the lighter eye, and comes to the conclusion that hereditary influence as a causative factor in heterochromia has not been clearly established. From these observations, and from the experienceof other ophthalmic surgeons, there can be no doubt that intra ocular disease, especially when associated with increase of intra ocular tension, may bring about, under certain conditions, anterior depigmentation, partial or complete, of the iris of the diseased eye. But beyond this limited group of cases, in which irregular iris pigmentation is associated with disease (frequently antecedent) of the affected eye or eyes, there is a larger group (growing in size in proportion to the care which is exercised in searching for and examining the cases) in which the irregular pigmentation of the iris is congenital and unassociated with any evidence of disease. Thus Thorpe (26) and Allan (2c) record such cases. J. Ross(2rf) found 11 cases of heterochromia in a series of .5000 patients in which the irregular eye colour was not associated with any symptoms. In these congenital and healthy cases the demarcation between the pigmented and the less pigmented, or the unpigmented portions of the iris in the same eye, is often sharply defined with clear tangential margins quite unlike the merging of pigmented into unpigmented areas in disease. * Further, in a certain number of these congenital heterochromia cases a familial incidence strongly suggests a genetic origin. When we find the heterochromic condition closely associated with certain varieties of domesticated animals, and in individuals in which there is no evidence of ocular disease, when further we find that it makes its appearance in man and in animals during the inter-breeding of individuals and varieties of different eye colour and pattern, then we are, I think, fully justified in considering that the whole subject of heterochromia of the iris should be re-investigated from the genetic point of view. It is the object of this paper to record some observations which bear on this hereditary aspect of the problem. Coincidentally with the impoi-tant discovery announced by Hurst(6) in 1907 (and independently by Davenport later) that the inheritance of eye colour in man followed Mendelian lines, a further attempt was C. J. Bond 101 made by Hurst to subdivide his duplex type into a self-coloured pattern in which the pigment was spread over the whole anterior surface of the iris, a ring pattern in which it was deposited in a circle round the margin of the pupil, and a spotted pattern in which it was collected into discrete spots or patches. Owing to lack of material and to the fact that deposition of pigment tends to increase during childhood, Hurst was unable to establish fully the genetic relations between these types, beyond showing that the self-coloured behaved as a dominant towards the ringed pattern. From Hurst's description it would appear that the genetic factor or factors which control eye-colour in the human species (although they may be classified into two or more sub-types) operate under normal conditions in both eyes equally, that is to say they are bi-lateral or bi-iridial in action. It is the object of this paper to draw attention to some examples of irregular iris pigmentation in man and in some varieties of domesti- cated animals and bii'ds in which this symmetrical arrangement is departed from. It has been known for a long time that in a certain proportion of cases in the human species, perhaps one or two per 1000, the two eyes of the same individual are of different colours. When this condition of heterochromia does occur, according to my own experience, the darker or coloured eye presents some shade of the duplex type, either arranged on the self-colour pattern, or more frequently affecting a larger or smaller portion of the iris either in a continuous sheet or in discrete sections, the remainder of the iris being blue or some lighter shade of the coloured pattern. The other or lighter eye is either simplex or more generally a lighter shade of the duplex pattern of the coloured eye. Different degrees of this condition of asymmetrical colouration are met with, varying from complete heterochromia to one small sector of darker colour in an otherwise duplex eye. In the course of the examination of the pigment distribution in a considerable number of individuals an irregular type of the duplex pattern will be found which does not conform to the self-coloured or the ringed or the spotted pattern described by Hurst. In an otherwise blue or grey, i.e. a simplex eye, a portion of the iris, generally embracing the whole diameter from periphery to pupillary margin, and more or less triangular in shape, with its base at the periphery, will show in different cases different degrees of pigmentation from light yellow to dark brown. 102 On Heterochromia Iridis in Man and Animalx In some individuals this duplex ray takes the form of a darker pigmented sector or patch on a ground colour of lighter duplex instead of a blue background. This radial sector of duplex pattern in an eye of simplex or lighter duplex ground colour, I propose to call the ray pattern of the duplex type. Iris Structure in Man. Although as we shall see later cases of irregular pattern of iris pigmentation also occur in animals and birds, yet the pigmentary deposit is less sharply defined in outline, less sectorial or ray-shaped in them than in man. It is probable that this difference in pigmentary pattern may depend on the very definite radial arrangement of the connective tissue stroma of the iris in the human subject. This frame- work tissue and the muscular fibres which dilate the pupil form a network of radiating fibres with lozenge-shaped interstices which generally converge to form a ring with knot-like intersections at a little distance from the pupillary margin, and it is in the situation of this ring of intersections that the greatest deposit of pigment occurs in the so-called duplex ring pattern. This ray-like formation of supporting tissue is well seen in the blue human iris in which there is no obscuring anterior pigment, and even more clearly still in the albinotic iris. In the iris of birds and of many animals on the other hand the concentric zone-like disposition of the fibres is more marked and obscures the radial pattern. Prevalence of the Ray Pattern in Man. Out of 200 consecutive eye-cases attending Dr Henry's clinic there were three examples of this ray type, that is 1^ per cent, of eye cases (not of the general population). Of these one was a brown or duplex ray on a blue or simplex background. Two were dark brown rays on a ground colour of lighter brown and in one of these a few dark pigmentary spots were present in aildition to the pigmented ray. Through the kindness of Mr Ridley and other medical men and nurses I have examined 40 other cases of the ray pattern in the last six months. In 21 of these a well-defined duplex triangular ray or rays existed on a simplex background, the other eye in the same individual being of the simplex type. C. J. Bond 103 In 19 a dark duplex ray was present on a lighter shade of brown or yellow as a background, the other eye being also light duplex. In two of the 40 cases there was more than one ray. In five cases the pigment covered more than half the surface of the iris in a con- tinuous sheet with sharply defined ray-like margins. In nine cases the duplex ray in the one eye was associated with the ring duplex pattern in the other eye. In one case both eyes were of the duplex type, but in the left eye the anterior pigment was absent from two small triangular areas, one on either side of the iris in the equatorial line, thus giving the appearance of two pale blue rays in these situations. In one case only was the irregular ray pattern bilateral (E. Frake, Pi). The Hereditary Transmission of the Ray Pattern. In 19 cases in which the eye colour of the parents could be verified by personal examination, in 15 one parent was duplex and one simplex, in four cases both parents were duplex. Four families (Baines, Frake, Masters and Whitby) are of especial interest in which more than one example of the ray pattern occurred in the same family, and their pedigrees are shown as far as the facts could be ascertained in the accompanying tables. In the "A" family (Masters), Fig. I, two sisters D. M. and I. M. showed narrow but distinct dark brown rays on a yellow and blue background respectively in different eyes and on different sides of the iris in each case. In one the other eye was faintly duplex, in one simplex. The father of these children was simplex and the mother dark duplex. Three other children were regular simplex and one regular duplex in the same family. In the "B" family (Baines), Fig. II, the father G. B. had a well- marked duplex ray covering the inner half of the left iris, the remainder being blue and the right iris yellow duplex in the ring form. One daughter F. B. had a corresponding yellow brown ray covering the outer side of the left iris, the inner half being blue and the right eye yellow brown ring duplex like the father. One son W. B. the lower half and inner and outer quadrants of the right iris were brown leaving a ray of blue in the middle of the upper half of the iris. The left eye was ring duplex like the father and sister. The mother of this second family of ten children, of which two were of the ray pattern and the remainder all simplex with the exception Journ. of Gen. ii 8 104 On Heterochromia Iridis in Man and Animals of one boy faintly duplex, was herself simplex with a duplex mother and a simplex father. The father of the male parent was simplex and the mother unknown. The father G. B. had had a previous family (Family I) of eleven children by his first dark duplex wife ; of these eleven children eight were dark brown and three simplex, and no cases of ray or irregular pattern occurred in this first family. In the "G" family (Frake), Fig. Ill, the father (of unknown parental eye-colour) is a ray-duplex of self-type, that is to say the iris is dark brown leaving some ray or lozenge-shaped blue spaces round the pupil in both eyes. The mother is a self-coloured duplex of yellow tint. Of the nine children one son E. F. has a dark brown, almost black ray in the outer side of the left iris, the remainder of the iris and the other eye being light brown. One daughter L. F. has multiple dark brown rays covering the greater part of the inner half and part of the outer half of the left iris, the remainder being blue and the right eye dark brown. One son A. F. has a dark patch in the upper and outer part of the right iris, the remainder of this and the left iris being light brown ring-duplex. Four Families {Masters, Baines, Frake, Whitby) showing Heredity of Ray Pattern. Bracketed circles represent the two eyes of one individual, the lower circle represents the right eye. " A " Family. Masters. Fig. 1. C. J. Bond 105 " B " Family. Baines. g d f^ Fig. II. G" Family. Frake. Fig. III. 8—2 g ig 0. J. Bond 107 One daughter K. F. has a black spot on a lighter duplex back- ground on the lower half of the right iris, the left also being brown duplex. Four children W. F., G. F., I. F. and Al. F. are dark brown self- duplex, and one B. F. is a green self-duplex. The father I. F. has two sisters also with irregular iris pigmentation of the ray-type. In the " D " family (Whitby), Fig. IV, the father is a heterozygous ring-duplex of irregular pattern with excess of pigment in the upper part of the ring; the mother is a heterozygous ring-duplex, and three cases (Florence, Ethel, Kate) of ring- pattern heterochromia occur in a family of ten children. In two other families (Martin and Cavanagh) familial facts occurred. In one (Martin) a duplex ray in the child was associated with an irregular dark patch in a ring-duplex in the father (Case 9, Fig. V and Case 9, Fig. VI). In one (Cavanagh) a duplex ray in the mother was associated with a dark patch in a ring-duplex in the son (Cases 22 and 23, Fig. V). The following diagrams will serve to illustrate the form the ray pattern assumed, and the position the coloured sector occupied on the iris in 24 cases, in which, with the exception of cases 9, 22 and 23, no familial incidence was recorded. Irregular Type of the Ring Pattern. One case, a woman aet. 34, Mrs A. B. (Case 8, Fig. VI), was seen of abnormal structure pattern apart from pigmentary abnormality in a simplex eye. In both blue eyes an inner ring of dark blue immediately surrounding the pupil was itself surrounded by a wider ring of light blue reaching nearly to the periphery of the iris. This outer ring had the dog-toothed margin and the radial striated appearance of the simplex iris, the peculiar appearance of two concentric rings being due to the outer zone of more opaque radial fibres round the inner ring of circular transparent fibres. In Case 1 L. C. a broad brown ring surrounded the pupil in the right eye and a narrow yellow ring the pupil of the left eye, giving an appearance of heterochromia in the two eyes. In Case 5 (shown also as Case 12 in the ray-table) is a duplex ray in an otherwise simplex right eye. This ray was associated with two dark pigment patches on the lower half of the sclerotic. In one Case 6 N. H. the difference in area and degree of 108 On Heterochromia Iridis in Man and Animals && 11 P H o ) v"^ TV ° ) 12 o &®e^&G&G 22 1. Higginson. 2. Lilley. 3. Tate. 4. Tompkins. 5. P. B. G. Mrs H. 7. Scott. 8. S. H. 0. Martin. 10. Turner. 11. A. G. 12. N. E. 13. Randall. 14. Stevens. 1.5. Aston. 16. Thomson. 17. Mrs Day 18. Nunn. 19. Jackson. 20. Taylor. 21. Bodycote. 22. Cavanagh ? . 23. Cavanagh i . 24. Grundy. Fig. V. C. J. Bond 109 pignieotation in each ring was so marked as to make the right eye appear dark brown and the left eye light yellow. In one Case 7 E. E. a yellow brown ring was associated with black pigment in each eye most marked in the lower half of each iris. In Case 9 the spots were limited to the right eye. This man was the father of the ray-duplex (Case 9). Ring and Spotted Patterns. 2 3 8 ®e 1. Colton. 2. Martin. 3. Hives. 4. N. Jones. 5. N. Richards. 6. N. Harvey. 7. Evans. 8. Mrs A. Ball. 9. Martin. Fig. VI. In one case B. C. No. 23 ray pattern, a duplex ring with irregular black spots in the upper half of the left iris in the son, was associated with a brown duplex ray in the outer half of the right iris. In the mother (Case 22) the rest of the iris and the left eye being blue. Prevalence of the ring pattern. There were 14 ring pattern cases in 88 duplex individuals occurring in the consecutive series of 200 cases of Dr Henry's clinic. Prevalence of the spotted pattern. In 26 individuals out of the 200 cases spots or patches of darker pigment were present on a lighter duplex background and in a few cases on a simplex background. Thus we see that out of 22 examples of a single ray only two were above the horizontal pupillary equator, two were on the equator and 110 On Heterochromia Iridis in Man and Animals Distribution of the Spot and Hay Paiterns on the Iris. Spotted Pattern : In both eyes 7 Above the horizontal equator 5 On the horizontal equator ... 4 In one eye... 19 -j ^bove and below equator ... 4 Below equator... ... ... 18 Distribution of the Ray : Single Hay above equator ... 2 ,, on ,, ... 2 „ below „ ... 18 Multiple rays above and below 11 Total 33 18 helow it in various positions in the lower half of the iris. In the 11 cases in which a large portion of iris surface was covered by multiple duplex rays the greater number and wider and more deeply pigmented rays occurred in the lower half of the iris. This inferior situation of the duplex ray is suggestive when we recall the fact that congenital coloboma of the iris, which is often bi-lateral and which is probably dependent on imperfect closure of the choroidal fissure, is nearly always found in the lower half of the iris and usually in the downward vertical direction. The occurrence of coloboma of the iris has been recorded in the upper portions of the iris, and an attempt to explain this fact has been made by supposing that in these cases some rotation of the developing optic cup has carried the choroidal fissure out of its usual inferior position. It is also interesting to note that in some of the amphibia (frog and toad and some newts) a colour coloboma of the margin of the iris in the vertically downward direction normally exists in the adult animal. Plate VII, fig. 3. The fact that while coloboma is nearly always vertically downwards the pigmented ray is rarely in the exact vertical midline but usually displaced to one or other side of the lower half of the iris, would at first suggest a different origin for the abnormality in the two cases. But it is necessary to remember that coloboma is due to non-closure of a gap which nearly always forms in the same position, while the ray of pigment is the result of the in-growth of mesoblastic tissue which eventually becomes pigmented through this choroidal fissure, and the spreading out round the globe of this tissue in a radial or fan-shaped manner, to form the iris etioma. The habitual presence of the pig- mented rays in the lower half of the iris may be due therefore to the C. J. Bond 111 failure of this pigmentary tissue to spread from its point of entrance further round the globe in these abnormal cases. Irregular Iris Pigmentation in Animals. My attention was drawn to this subject by finding that out of 100 wild rabbits shot on a small uninhabited island in the Orkneys four animals exhibited unequal pigmentation of the iris in one or both eyes. In three animals the upper portion of the iris in both eyes above the horizontal pupillary equator was blue, the animal being partly wall-eyed, while the lower or lower anterior portion was deeply pig- mented (duplex type). In one animal this irregularity was limited to the left eye. Plate VI, figs. 1 and 2. It is well known that " wall " eye occurs in many species of domesti- cated animals. I am indebted to Dr Sydney Turner for some interesting information about " wall " eye in Great Danes. The wall-eyed condition, that is the simplex type of iris, may be present in both eyes in the same animal or it may affect one eye only. In the latter case it may affect the whole or only a portion of the same iris, the remainder being of the normal brown colour or duplex pattern. While " wall " eye is most common in the Harlequin variety of the Great Dane, that is in an individual of a bi- or tri-coloured patchwork pattern or piebald coat colour, it is also found in other breeds of dogs such as the English Collie, especially the " marled " variety, and in the bobtailed Old English Sheep Dog and I have also seen it in the Dalmatian. It is also noteworthy that in the individual dogs that I have examined the unpigmented areas frequently occupy some portion or the whole of the lower half of the iris, the opposite of the condition found in man. " Wall " eye has also been observed in piebald and in so-called " skewbald " horses but not exclusively in this breed. This association between irregular iris pigmentation and patchy Harlequin coat is important. Thus in the series of the 100 Orkney rabbits there were 81 of the wild grey colour, the remaining 19 showed some irregularity of coat pattern, five had white patches on or in the neighbourhood of the right shoulder, five on the left shoulder, three white patches on one or more limbs, and six had white colouration of the forepart of the body, neck 112 On Heterochromia Iridis in Man and Animals and head, roughly correspoading to the Dutch pattern. (See Illus- tration.) Distribution of Coat Colour in Orkney Rabbits. Wild Grey ... 81 / White patches on Eight Shoulder 5 100 Patched 19 Left Limbs Dutch Pattern irregular imtcli Pattern in Orkney Kalibits a.'isociated with "wall " eye. Now it was only in these rabbits which showed the Dutch pattern of coat colour that the " wall " eyes were observed. Plate VI, figs. 1 and 2. I understand from Prof. Punnett that " wall " eye occurs in the Dutch breed and it is known that five or six years ago some tame white, or brown and white rabbits were turned down by a farmer on this uninhabited Orkney island, it is possible therefore that some of these were of the Dutch type. Heterochromia in pigeons. I cannot find any systematic record of eye colour in pigeons, but I have observed one or two points in the course of my own breeding 0. J. Bond 113 experiments in pigeons during the last seven years which are of interest in this connection'. It is well known that whiteness of plumage is associated in pigeons with a dark brown iris or "bull" eye. Bull eye is an expression used by fanciers to denote a dark brown eye which looks black at a distance and in which it is difficult to see the outline of the pupil without close examination. If however the bull eye be examined at an angle with a lens, an outer zone of pinkish red colouration can be observed near the periphery of the iris which at first suggests red pigment in this situation. After removal of the eye however and the emptying of the blood vessels the pink colour largely disappears and microscopical sections of the iris show that the pink appearance is due not to the deposition of pigment but to exposed blood vessels on the anterior surface of the iris. Thus the bull eye is a simplex eye in which the posterior uveal pigment is seen through the delicate iris tissue. A homozygous white fantail cock with "bull" eyes was mated to a black fish-tailed short billed tumbler hen with pink eyes-. The F^ offspring of this cross were black and white, and brown (with blue) and white hybrids, all with dominant orange red or duplex iris. Two of these, a black and white cock and a brown blue and white hen (brother and sister) were mated together and produced in the F^ generation : ; Chocolate Brown Black Black and White Brown, Blue, and White White 2 4 21 11 13 Eed eye Red eye Eed eye Eed eye " Bull " eye Of these F„ heterozygotes a black and white cock with orange red eyes was mated to a brown, blue and white hen, with orange red eyes, producing in the i^s generation : Black and White Brown, Blue and White Blue Blue and White Almond Almond and White White 4 5 2 3 1 1 2 Of these the black and white, brown and white, almonds, and almonds and whites, have the dominant red eye, the white the recessive ' Heterochromia in pigeons is apparently according to fanciers more common in Tumblers and chiefly in the Pied varieties, it also occurs in Homers. ^ It should be stated that in the pigeon experiments the pairs, when once mated, were not confined, but were allowed to mingle with other birds in the same loft. If care be taken to keep all the adult birds properly mated, I have not found any difficulty arise from non-isolation. 114 0)1 Heterochromia Iridis in Man and Animals bull eye, and only the blues, and blues and whites show irregular iris pigmentation. One of the blue and white birds of the ^3 generation is especially interesting, having a full orange red eye on the right side and a " bull " eye on the left. Plate VII, figs. 1 and 2. On careful examination with a lens however the red anterior pigment in the right eye is found to be partly wanting in a segment of the lower half of the iris downwards and a little forwards from the pupil, leaving the underlying brown or "bull" ground colour exposed in this situation. This individual bird thus shows a duplex pattern with coloboma of the colour pattern in the right eye and the bull eye which corresponds to the human simplex type in the left eye. This bird also showed some irregular white patches on the head indicating further irregular pattern of feather colour. The details of the breeding of these birds are as follows : White Fantail Bull Eyes Black Tumbler Pink Eyes Black aud White Pink Eyes 44 I Brown, Blue Brown and White 2 11 Black and White 21 Almond 1 Pink Almond and White 1 Pink 1 I Brown, Blue and White Pink Eyes 26 White 13 Irregular iris pigmentation Brown, Blue and White White 5 2 Pink Bull In this case then the heterochromia and the irregular duplex pattern in the right eye have appeared in the F^ generation during the repeated interbreeding of the black and white, and brown, blue and white heterozygous offspring of a bull eyed white fantail, and a pink eyed black tumbler. C. J. Bond 115 This heterochromic blue and white tumbler-fan hybrid was mated to a full sister, almond in colour with pink eyes, with the following result : Blue and White x Almond Heterochromia i Red $ Whil Blue Blue and White Almond Almond and Wliite White 12 14 2 4 6 and the reappearance of heterochromia in some number unrecorded of the blue and white birds. Thus it would seem that the mating of a self-colour black with pink eye with a recessive white with " bull " eye is associated with the appearance of broken-up feather colour pattern and a broken-up iris anterior pigment pattern as in the Orkney rabbits. Moreover the irregular iris pattern is so far only found in the blue and white birds, that is in birds of a dilute black and white colour pattern. The gametic factor or factors, which in the self-coloured and self- white parents control the whole feather pattern, and in the self-coloured iris and the " bull " iris control the whole iris pattern, have undergone some change by which in the birds with parti-coloured eye and feather pattern they now control independently different feather areas and separate eyes and different portions of the iris in the same individual, and the question arises, What is the nature of the change in the con- stitution of these gametic factors which is responsible for this altered behaviour of unit characters ? Harlequin feathei' colour pattern in pigeons. The result of mating two self black fantail cocks of prize strain with orange red eyes from the same loft with two pure bred white fantail hens with "bull" eyes in 1905 was to produce F^ hybrids of different type in each case. In the "-4" mating most of the F^ hybrids were black and white piebalds with bull eyes, in the " B " mating all the F^ hybrids were blacks with (in most cases) a few white feathers on the rump and one or two white primaries in one wing. These black hybrids had the orange red eye. [The details of these two matings are given in the tables on pp. 118, 119.] But the point of interest is that the self mating of the F^ hetero- zygotes of the "A" and " B" cross respectively resulted in a different proportion of extracted types in the F„ generation in each case, although the proportion of selfs to pied, two to one, was about equal Blacks Blues Black and Wliite Harlequin 26 14 25 116 On Heterochromia Iridis in Man and Animals in both. The self mating of a pair of the "harlequin" hybrids of the "A" cross produced in six years: Black and White Blacks Blues Harlequin Whites 11 4 17 22 (Total = 54) The self mating of a pair of the "black" hybrids of the "B" cross produced in the same time : Black and White Whites 16 (Total = 81) see Chart, pp. 118, 119. It is of interest to compare this result in pigeons with the two extracted types of the " Irish " variety in hooded rats obtained by Doncaster and Mudge by crossing the wild grey with the albino rat (Bateson(9), p. 84). On re-mating the original black cock of the "A" mating to another white fantail hen of a different strain ("C" mating) all the offspring F^ were blacks with white rump feathers and white wing primaries like the Fi black offspring of the " B" cross. This result of the second mating shows that the difference in parental gametic constitution which led to the difference in colour pattern in the .Fi hybrids of the "A" and " B" crosses was introduced by thewhite recessive female parent of the "A" cross, and it is this difference of gametic constitution in this parent that led also to the unequal distribution of extracted types and the excess of recessive whites in the F„ generation of the "A" cross over that in the JP, generation of the " B " cross\ The association between eye colour and feather colour was preserved in these parallel matings, the harlequin Fi offspring of the "A" cross retaining the " bull " eye and the black Fi offspring of the "B" mating the orange eye. The bull eye of these F^ and extracted F„ harlequin birds, however, has a pinker appearance than the bull eye of the normal white fantail-. Heterochromia in cats. In his experiments on heterochromia in Angora cats in 1907, Przibram (7) found that the mating of an asymmetrically coloured animal having one blue and one yellow eye with a symmetrically 1 The distribution of recessives, intermediates and dominants as revealed in the charts (pp. 118, 119) suggests a grouping of these three classes of offspring, especially in the case of the white recessive bii-ds. 2 In both matings the recessive whites showed the " bull " and the dominant blacks the orange eye. C. J. Bond 117 coloured animal having two blue or two yellow eyes resulted in the pro- duction of both asymmetrically and symmetrically pigmented offspring. Przibram concludes that asymmetric animals can be traced back to asymmetric ancestry. The asymmetry can also be altered during hereditary transmission, thus either eye colour of the asymmetric parent can appear in the symmetric form in the offspring. The conditions (genetic) under which asymmetry of eye colour first appears are unknown. Association between eye colour pattern and skin or coat colour pattern. Recent researches by Pearson, Nettleship and Usher on albinism in man (8) show that the piebald, that is the black and white skin colour pattern, does occur though rarely in individuals belonging to the coloured races of mankind. In some of these cases of piebald negroes a familial association with complete albinism has been traced, in others with leucoderma and some other conditions having a pathological or somatic origin. On the other hand a piebald skin colour, apart from pathological conditions, has not (so far I believe) been recorded among European races. This may be due to the fact that no systematic search has been made for this condition. Some authorities, A. R. Gunn(13), are of opinion that partial albinism does occur among Scotchmen but in these, as in some cases of partial albinism, the dissociation is between eye colour and skin and hair colour, rather than between different areas of skin colour, though the important fact that albinos of different strains may carry different pattern factors is suggestive. Thus, although a considerable number of cases of partial or complete heterochromia of the iris occur during the inter-breeding of duplex with duplex, and duplex with simplex types of eye colour, no cases of piebald skin colour have been recorded so far as arising during the inter-breeding of light complexioned and dark complexioned European varieties. If some segregation of skin colour factors does occur in sub- sequent gametogenesis in the offspring of mulatto hybrids as stated by some observers, even in such cases the segregation process would seem to affect the self-colour patterns as a whole. In this respect then the black and white human hybrid (mulatto) and the pied animal hybrid, e.g. the Dutch or Orkney rabbit, are dissimilar. 118 On Heterochromia Iridis in Man and Animals S '^ ■ &7 — B M C^ -^ tt. X X ^ ^" d n -m iz; — t— 1 eg H •^ ^ a S ot- fe « a) «) ^ n a an nn n s n -nn n ssb^ n sn n n X X 0 XX sc o 03 o CD O 05 o 05 00 o OS ^> OS p^ cS ^ m •-1 CD ■ CV c*^ s "s a^ X g c^ o ei to o 05 o C. J. Bond 119 G I— 1 D D DD n n n 01 B T3 >0 n ns a S a n n n m E 0 [xJH [xJH S 0 "it 1— ( ■ ■■ -a ■ ■ ■■ ■ J3 „ to CO O Q 1-5 1-2 H, fee ^ ■< O 1. a DO <| Hj TJ n1 > ^ o ^ n 4-* o CO O c^ 03 Ss t>0-i^ 01 ,a ¥ != ^ -4J o ■:-" a 0) ?>■> ■^3 l^« ^ a Ol -r) -(-3 pci a l5 t = resn and Wl White. N S m a cq J3 an BD annnn DD n aa HSf!! a 0 J ^ 5^ -^ b a O « fe S h? 00 o Ci 03 Q fa Ol o C5 -9 S ?:! C a, .03 0) j; OJL bo a- 0) O rH OS s CC o p. _£« 01 S a ^ t- a 4 1= ja a ■X} o II pq ti 03 O 03 — ^ 'I m fa -a a c3 +^ bo 1 ^ Ol 01 .lil :a J« n <4H = bb a 3 o ^ o ^y > O) ^ y' Fig. I. Fig. 2. Fig. 3- JOURNAL OF GENETICS, VOL. U. NO. 2 PLATE VIII Fig- I- JOURNAL OF GENETICS, VOL. M. NO. 2 PLATE IX Fig. I. \ r-''''^ x. y ^ V .1 -vy Fig. 2 C. J. Bond 129 EXPLANATION OF PLATES. PLATE VI. "Wall eye" in an Orkney rabbit of Dutch colour pattern. Note absence of anterior pigment in the upper half of the left iris and the upper and anterior portions of the right iris. Fig. 1. Left eye. Fig. 2. Eight eye. PLATE VII. Heterochromic Pigeon. Fig. 1. Left bull eye. Fig. 2. Eight orange eye with a gap in the orange pigment (colour eoloboma) in the lower half of the iris. Fig. 3. Adult frog shows gap in anterior pigment of iris (colour eoloboma) in downward vertical direction in the lower half of the iris. PLATE VIII. Fig. 1. Nine children, the oiispring of an English woman (wavy hair) and a West African Negro (corkscrew hair). The two youngest (marked x ) show differentiation of hair pattern with wavy hair on the vertex. PLATE IX. Fig. 1. L. M. Boy aet. 4, shows wavy European hair pattern on vertex, corkscrew pattern on sides. Fig. 2. Girl aet. 6, shows corkscrew negro hair pattern all over scalp. SECOND REPORT ON THE INHERITANCE OF COLOUR IN PIGEONS, TOGETHER WITH AN ACCOUNT OF SOME EXPERIMENTS ON THE CROSSING OF CERTAIN RACES OF DOVES, WITH SPECIAL REFERENCE TO SEX-LIMITED INHERITANCE. By RICHARD STAPLES-BROWNE, M.A. CONTENTS. PAGE Introduction .......... 131 Brief statement of results ....... 132 Account of the experiments ....... 136 Bock Doves used in experiments 136 Rock Doves x White Domestic Pigeons 139 White Pigeons used in experiments ..... 141 Types of birds produced 141 Details of the matings ........ 144 Carriers, Dragoons, Owls and Fantails used in the experiments. 155 Silver Owls x Black Fantails 156 Dun CaiTier ? x Blue Dragoon cf ..... . 157 Crosses between dark and white races of doves . . . 158 Introduction. In the Proceedings of the Zoological Society for 1908, p. 67, I published a report on the inheritance of colour in Domestic Pigeons with special reference to reversion. The colours chiefly dealt with there were black and the "reversionary blue" of Darwin, which may be considered as the type classed as "black-chequer" by the fanciers (Plate V of the report), and also the relations of these two forms to white. 132 On, the Inheritance of Colour in Pigeons In the present paper the colours considered are black, dun, blue and silver, their relations to each other, and the behaviour of the two latter when mated to white. The experiments on these colours are still in full progress, so that this report must be considered merely as a preliminary account of them. Enough has, however, been done to demonstrate a sex-limited inheritance in silver. The same may possibly be shown in dun also on further experiment'. It is found that, whereas a black ») >) ») f» Silver x Silver 31ue X Silver >» ») 31ue X White j» ?» 3ilver x White Experiment Numbers 53, 70, 72 47, 49 51, 54, 55, 65, 66, 74 60 61, 68, 69 48, 71 59, 67 50, 52 64 56, 57, 58, 62, 73 63 Expectation All blue 13-5 blue, 4-5 silver 27 blue, 9 white 5-6 B., 1-9 S., 2-5 W. All silver All blue 11 B., 11 S. All blue 18-75 B., 6-25 S. All blue 9'5 B., 9-5 S. Result 20 blue 15 B., 3 S. 28 B., 8 W. B., 2 S., 2 W. 31 silver 12 blue 11 B., 11 S. 10 blue 20 B., 5 S. 15 blue 13 B., 6 S. Expe7-iments on Chequering. ^on-chequered x Non-chequered 47, 48, 49, 69, 70, 71, 72 55, 74 Chequered x Chequered ... 67 » .. ... 65, 66 61 54, 60 jhequered x Non-chequered ... 68 53, 59 All non-chequered 10-5 non-C, 3-5 W. All chequered 6 C, 2 W. 12 C, 4 non-C. 11-81 C, 3-94 non-C, 5-25 W. All chequered 9-5 C, 9'5 non-C. Experiments on Colour of Rump ^. White rump x White rump Blue rump x Blue rump White rump x Blue rump 47 5-25 W. rump, 1-75 B. rump 49, 70 All blue rump 72 All white rump 50 non-chequered 9 non-C, 5 W. 10 chequered 4 C, 4 W. 11 C, 5 non-C. IOC, 7 non-C, 4 W. 8 chequered 9 C, 10 non-C. 5 W. rump, 2 B. rump 12 blue rump 2 white rump is to say, that blue i.s a dilute form of black, and silver a dilute form of dun. Messrs Bonhote and Smalley, however, take the contrary view, regarding silver as dilute blue. As there is no other colour on which the two middle terms of the series can be tested (as they can for example in mice), it is not possible absolutely to distinguish between these two alternatives. In appearance some silvers may confidently be said to contain no black (e.g. Silver Rock), but in others (e.g. Silver Owl and Dragoon) the colour of the wing bars hardly differs at all from that of blues, and probably contains true black pigment. Unfortunately microscopical tests, though extensively tried, have not hitherto provided any satisfactory criterion between the various pigments, and do not add much to what can be seen on ordinary inspection. 1 In these experiments silvers are not iucluded, as it is impossible to be certain whether the rump is coloured or not. Journ. of Gen. ii 10 136 On the Inheritance of Colour in Pigeons Account of the Experiments. The numbering of the experiments herein described is continued from that of my previous experiments on colour contained in my first report. Thus the present series of crosses begins at Exp. 47 and ends at Exp. 91. The matings are divided as follows : Exps. 47 — 49 (see Table I) consist of matings of Rock Doves. Exps. 50 — 74 (see Tables II — V) consist of the matings of Rock Doves to Whites. Exps. 75 — 78 (see Table VI) consist of the matings of Owls, Fantails, Carriers and Dragoons. Exjjs. 79 — 91 (see Table VII) consist of experiments with Doves. Rock Doves used in Experiments. The specimens of Columha livia used in these crosses came from two sources : (1) three c/'s from a pair taken at the Isle of Achill, on the west coast of Ireland, and (2) one (/ and one $ from Lincolnshire. Irish birds were used in Exps. 50, 71 and 72 of the matings with white, whilst Lincolnshire birds were used in all the other crosses with whites. Irish Rock Doves. These birds were kindly sent to me in 1906 by Mr J. L. Bonhote, who had bred them in his aviaries from a pair obtained by him from Achill. He informed me that the birds there were quite wild, antl he saw no varieties in the flocks there. There were no tame pigeons within a radius of about thirty miles. Mr Bonhote has bred 19 birds in all from his Irish Rock Doves and their descendants, all true to type, with one exception. This bird was chequered, but since it was produced from a pair of birds that had their liberty, the possibility of a cross was not excluded^ From the descriptions of the crosses made with these birds it will be seen that no question arises as to their purity, and it was found that in F„ from the mating of an Irish Rock Dove with a white the pattern factor segregated out quite cleanly (v. Exp. 51). Lincolnshire Rock Doves. These birds were obtained in 1903 from Lincolnshire through a dealer's advertisement. They were stated to be wild caught, but I could obtain no reliable information concerning them. Their appearance was identical in every respect with that of the Irish birds and other pure 1 V. Bonhote and Smalley, P. Z. S. 1911, p. 605. R. Staples-Browne 137 specimens. On breeding them together, however, certain varieties were obtained, and, as will be seen, they were obviously heterozygous in at least two characters. It frequently happens that semi-domesticated birds join the Rock Doves in their breeding haunts, and no doubt often ci-oss with them. It is stated in Yarrell's British Birds, 4th edition. Vol. Ill, p. 14, that " even in Yorkshire and Northumberland the birds found are open to the suspicion of not being pure wild birds." In 1906 I visited several caves near Flamborough Head which were frequented by these birds in large numbers, and, although no varieties were seen on the day of my visit, I was informed by the boatmen that lighter and darker birds and whites were frequently seen and shot there. Test experiments with Lincolnshire Rock Doves. When the Lincolnshire Rock Doves were bred together a mixed generation, consisting of three distinct types, was produced. To determine the relationship of these types to one another matings in the direct line were continued and two more generations were raised. The details of the experiments are given in Series A (Exps. 47 — 49), and the results tabulated in Table I. Types of birds produced from the Lincolnshire Rock Doves. (1) Typical G. livia. These birds were identical in every respect with their parents. This type behaves as a dominant to the other two types produced. One of these birds, mated to white, forms a starting point of some of the experiments described in Series B {v. Exp. 52). (2) Blue riimped Rock Dove. The plumage of this type resembled that of the sub-species of Rock Dove known as C. intermedia. The colour of the rump was slightly lighter than that of the back. On examining the series of skins of C. intermedia in the British Museum I noticed that specimens varied slightly in the colour of the rump, some being darker than others. Mr Blyth informed Darwin that the rumps of C. intermedia were sometimes albescent {Animals and Plants under domestication, 2nd edition, Vol. I, p. 193). In the whole of these experiments thirty birds of this type have been produced, and although the colour of the rump varied slightly, the character was always quite distinct, and could be seen at a very early age. In the following descriptions this type is alluded to as Blue with no white feathers (Bl. no wh.). 10—2 138 On the Inheritance of Colour in Pigeons (3) Silver. In this type the hUie of the Rock Dove is replaced by a light silver, or, more strictly speaking, cream colour, whilst the wing and tail bars are dun. The head, neck, flight feathers, and tail are much lighter and browner than those of the blue, but are considerably darker than the plumage of the wing coverts, back, breast, and under parts. It is extremely difficult to determine with certainty whether the rump is a very light shade of silver or white, but after examining a large number I did not feel convinced that I had found a really white-rumped bird. In the figures given for the experiments on rump character, therefore, these birds are omitted. Silvers are recessive to both types of blues described above, and breed true when mated together. The silver $ produced by breeding together the two Lincolnshire Rock Doves formed the starting point of the experiments described in Series C. TABLE I. Experiments icith Lincolnshire Bock Doves. Offspring ^ ■ Origin Also Origin Also Blue Typical Exp. from used in from used in no Columba No. Female Exp. Exp. Male Exp. Exp. white livia Silver 47 Typical C. livia — — Typical C. livia _ — 2 5 1 (no number) (no number) 48 Silver 43 47 5.5,56,57, Typical C. «;!)ia 44 47 50,-52 4 6 — 58, 68 49 Blue, no wb. 27 48 — Blue, no wh. 39 48 — 8 — 2 Details of the matings of Lincolnshire Rock Doves. Series A. (v. Table I.) Exp. 47. Typical C. livia ? x Typical C. livia J". These two birds, when mated together, produced eight offspring, of which five were typical C. livia, two were blue with no white feathers, the rump being a lighter shade of blue, and one was silver with dun wing and tail bars, the rump being apparently a very light silver. Now since subsequent experiments show that blue is dominant to silver and white ramp dominant to blue rump, we may conclude that ha % o a ^ ml' S & o o^ a; p ? ^ I ^' I I I I = I I I I I g <>3 a c- 0 cS co >o fe OJ Q) -4J J3 ^ -a ^ & & OS 10 01 CO 10 go' 10 CD U3 10 00 00 00 ^ :f ^ OJ 1 d d OQ w. CO M m IB lid 0 c^ 00 OS 0 ^ 10 >o \n 10 «5 to X -S fe; ^ 02 ■ 5. „ ,, no white feathers, 1 J Silver, non-chequered, much white, 1\ Silver, chequered, very few w.f on rump and thighs, 1. White 2. The numerical results of this F^ mating follow fairly closely the Mendelian ratios, the observed figures being : Coloured : White : : 8 : 2. Of the coloured birds : Blue : Silver : : 6 : 2. Chequered : non-chequered : : 6 : 2. White feathers in plumage. No w.f. : very few w.f. : several w.f : : 1 : 2 : 5. Exp. 61. Silver chequei-, no wh. $ 31 x Silver chequer, no wh. ^ 2. Both these birds were raised in Exp. 59. The mating was continued for two years, and 16 young were produced, all silver, of which 11 were 1 This bird was au intermediate and is counted as non-clrequered. R. Staples-Browne 151 chequered and 5 non-chequered '. The Meudelian expectation on this mating was chequered : non-chequered :: 12 : 4, with which ratio the figures obtained comply. No white feathers were produced ; we may therefore presume that white was not being carried by either parent. In the nest a few of the birds were thought to have some white feathers, but these were seen to be Hght silver when the birds gi-ew up. One bird also which had some feather deformity was counted as non- chequered in the nest ; on maturing, however, when the feathers attained their normal development, it was seen to be a light chequer. Series D. (v. Table IV.) Exp. 62. Silver chequer, no white ? 31 x White ^ 20. This small experiment was made to further demonstrate that the factor for blueness can be carried by a white bird. Here the silver chequer % is the same bird that was used in the last mating (Exp. 61), which there gave silver birds only when mated to a silver ^. The white (/, raised in Exp. 55, carries the blue factor, but not the chequering factor, which is introduced by the silver. Only two young were raised from this mating, both being blue chequered with black, having only a very few white feathers at the vent and thighs. Exp. 63. White $ 32 x Silver chequer, very few w.f. ) SO AG ,, ,, Giant form jj = i 1909 1911 3d 180 180 14/2/1 G Giant Pink Giant Primula sinensis Giant White (Sutton) Giant 7^», Royal White x Snow King ,, ,, 1908 130.11a •2A1 F3, Reading Pink x Crimson A White Sinensis King Normal sinensis >> 1909 25 Snow Drift ,, ,, jj 1911 Duchess ,, ,, ,j 1908 5 7i Normal White Queen Star Normal stellata ') ») 5Bp Cambridge Blue ,, ,, »» 1909 20/3/1 and 20/5 Snow King " )t »> ' The plants thus raised were typical Giant White Queen Star. Though possibly they were due to accidental selling of the female parent, they yielded no seed neither when self-fertilized nor when crossed with normal White Queen Star. F. Kebble 175 the outset that the method by which the following records were made — that of appraising gigantism by reference to the gross ap- pearances presented by individuals — is open to grave objections. For example, a large and massive flower may, if seen among a family of small-flowered plants, be classed unhesitatingly as a giant, although if it were judged side by side with indubitable giants, it might be relegated to the class of doubtful or semi-giants. On the other hand an observer who spends a considerable amount of time among plants of a certain kind gains in some measure a sureness of judgment with respect to the "points" of those plants which is not likely to lead him into very serious errors of observation. In spite of the drawbacks of the method of classification which has perforce been adopted in these experiments, the results which have been obtained appear to be worth recording both for their inherent interest and for the purpose of demonstrating that the phenomena of gigantism presented by P. sinensis are less simple than those exhibited by other plants which have been the subject of like investigation. For example, the genetics of the gigantism of sweet peas (Bateson, 1909 a) and of culinary peas (Keeble and Pellew, 1910) is of a fairly simple kind. Thus in Pisum sativum gigantism depends for its ex- pression on the presence of two factors. Of these growth-factors, the one induces excess of growth in length (factor for long internode), the other induces excess of growth in thickness (factor for thick internode). In the presence of both these factors, either in a pure or hetero- zygous state, the plant is a giant (G ft.), in the absence of either it is of mid-stature (3 — 4 ft.), and in the absence of both it is a dwarf (1—1 1 ft.). The gigantism of P. sinensis is built on less simple Mendelian lines. The experiments which lead to this conclusion, recorded in Tables IV, V, and VI, were made mainly at University College, Reading; though some records which are included in the tables are those of breeding-experiments carried out by Messrs Sutton and Sons at their trial grounds. The records derived from the latter source are indicated in the tables ; those in which the source is either not mentioned or indicated by the letters U. C. R. were carried out at University College. For access to the records of Messrs Sutton and Sons' experiments 176 Gigantism in Primula sinensis the very cordial thanks of the writer are due to Mr Leonard Sutton and to the firm's Primula experts, Messrs Macdonald and Tufnaii. From what has been said already with respect to the mode of inheritance of gigantism in Pisum sativum it follows that the F^ generation resulting from a cross between a pure giant and any other form consists of giants. A like result is not exhibited by Primula sinensis in the F^ generation derived from a similar cross. In some instances (see Table IV) the F^ jjrogeny of a cross between a giant and a normal form are of giant type : this is the case, for example, in the Fi of the crosses Giant Pink x Reading Pink and Duchess X Giant Lavender. In other instances, for example, in the TABLE IV. Crosses hetiveeii Giant and Normal P. sinensis. Results in F^ . I. Oases in which Gigantism appears to be more or less compii'tely dominant. Source of Experi- Record ment No. Nature of the Parents F, Results U. C. R.i OG— 7 31 Giant Pink x Reading Pink (Normal) 12 plants of giant type ,, 32 A Royal White (Giant) x Pink Stellata 14 plants, Howers like (Normal) those of Royal White (Giant) butfreerin habit and on longer pedicels „ ,, 32 F Pink Stellata (Normal) x RoyalWhite 11 plants, flowers like (Giant) those of Royal White (Giant) but freer in habit and on longer pedicels Sutton " II, p. 71 Duchess (Normal) x Giant Lavender Giant II. Cases in which the F-^ is intermediate with respect to Gigantism of flowei's. Sutton II, p. 20 Giant Royal White x Crimson King Semi-giant (Normal) „ II, p. 32 Crimson King x Giant White ... 8 plants, semi-giant „ I, p. 22 Royal White x Crimson King ... "Habit of flowers spoiled " III. Cases in which Gigantism of flower ap|)ear,s to be recessive. U. C. R. 80/07 Giant Pink x Lord Roberts Star Petals slightly fimbri- (Normal) ated ; flowers not re- corded as showing giant habit ,, 39/08 Lord Roberts Star x Giant Pink ditto ditto 1 U. C. R. =record of experiment carried out at University College, Reading. - Sutton = record of experiment from the record hooks of Messrs Sutton and Sous, Reading. F. Keeble 177 cross Giant Roj'al White x Crimson King the F-^ family consists of semi-giants, and in yet other cases the F^ plants were not recorded as showing giant habit of flower : whence it is to be inferred that if they possessed any symptoms of gigantism those symptoms were too slight to attract notice. The one case in which seed was obtained as a result of crossing Giant White Queen Star, though it must be recorded, is open to suspicion. The cross in question (Table III) was one between Giant White Queen Star and its parent, the normal White Queen Star. Two seeds only were obtained, and yielded plants of giant habit. It is highly probable that they were the result of chance self-fertilization of the giant, although it is to be noted that these F^ plants were sterile both with their own pollen and that of normal White Queen Star. A superficial consideration of the differences which subsist between the F^ generations might lead to the conclusion that two types of gigantism occur in P. sinensis : one type in which the gigantism behaves as a dominant character ; and the other in which it behaves as a recessive. Such a conclusion is not open to objection on general, theoretical grounds, and meets with support from the known facts of gigantism in human beings. For as Gilford {op. cit.) shows, overgrowth in man may be of a normal type or of a pathological nature. In the former it is due to an exaggerated but normal development : in the latter it would appear to be the consequence of the lack of a growth-controlling factor. So in plants, excessive growth may be the outcome of the presence of a factor for growth-acceleration (or for inhibition of cell-division), or may be due to the absence of a factor which in the normal plant controls and limits the amount of cell- growth in the interests of the several organs or of the organism as a whole. More careful examination of the results obtained with P. sinensis serves to show, however, that to apply such an hypothesis to their interpretation is certainly premature and probably unnecessary. Hence in the argument now to be developed it will be assumed that there is but one type of gigantism in P. sinensis and that gigantism is dominant to normality. The variable extent to which the giant character manifests itself in F^ generations must therefore be susceptible of explanation in terms of this hypothesis. An inspection of Table V shows that, as with the Fj generations, so with F.2 generations, there is a remarkable lack of uniformity with respect to the manifestation of gigantism. Thus the F„ and subsequent 178 Gigantism in Primula sinensis generations produced from self-fertilized F^ plants may show either a considerable preponderance of giants or an even more marked excess of normal (non-giant) forms. TABLE V. Crosses between Giant and Normal P. sinensis. Results in F., and subsequent Generations. I. Cases in which Giants appear in large numbers. Source of Record Experi- ment No. Nature of the Cross Sutton II, p. 32 Sutton I, p. 71 11. U. G. E. U. C. B. U. C. E. Results in F2 and F3 Crimson King x Giant White F-^ = 18 giant : 5 non-giant. F] = Semi-giant Several F3 = plants true to giant Duchess X Giant Lavender Fo, giant, F3, 18 plants all giant Fi = giant Cases in which Giants appear in small numbers. 120/07 Eoyal White X Pink Stellata F2, 67 plants of which 1 = giant, Fj = flowers in massive heads another F^, 54 plants no giants 80/07 Giant Pink x Lord Eoberts jP.,, 211 plants of which 9 = giant Star Fi = flowers slight sinensis none recorded as giant 14/2/1 Eoyal White x Snow King Fo, 13 plants, 11 non-giant, Fi = no flowers recorded as 2 giant g''^"* F3, of tiiant F2 = l plants all giant, petals overlapping with very fimbriated edges Fj, of ifiant ^3 = 14 plants all giant, petals overlapping with very fimbriated edges F3, of non-giant F.} = G plants, 5 non-giant, 1 giant F3, of non-giant ^0=11 plants, none giants Fj, of non-giant F-^=7 plants, none giants A clue to the significance of this diversity of behaviour is provided by E.xp. 120/07 (Table V). In this experiment a true-breeding giant, Royal White crossed with Normal Pink Stellata yielded an F^ in which the flowers though non-giant were borne in massive heads — owing, as shown in Table VI, to dominance of the stellata habit of free-tiering. TABLE VI. Dominance of Stellata over Sinensis Habit of Inflorescence. Eoyal White x Pink SteUata Fi = habit freer than Royal White, pedicels longer Fo = 22 stellata habit: 6 sinensis habit in 3 : 1 ratio =21 stellata habit: 7 sinensis habit F. Kebble 179 The Fi plants yielded an F^ generation which in one ease consisted of 54 non-giants and no giants and in another case was composed of 67 plants of which one was a giant. The ratio 66 non-giant : 1 giant suggests the further hypothesis that gigantism depends for its expression on three factors. Let it be assumed that a giant differs from a Normal Pink Stellata in the possession of at least three factors, which factors are either different in nature or — and more probably^similar in nature and of different distribution in the germ-plasm. Then when the giant of constitution AABBCC is crossed with a form which by virtue of its size and habit may be assumed to lack all three factors the result is an F-^, the members of which are heterozygous for all three factors. Thus : AABBCC X aabbcc, Fi = AaBbCc non-giant, and F. = lAABBCC : 63 plants of other constitutions, = 1 indubitable giant : 63 other plants, none of which appears as a giant when viewed beside the pure dominant giant form. Results which point to ratios of this order are exhibited in Table V. Thus in No. 120/07 the F„ of the cross Royal White x Pink Stellata consists of 67 plants of which 66 are non-giant and 1 is giant. In another F^ family of the same origin no giant appeared among 54 plants. The case of Snow Drift x Snow King (Table VII, I) is similar and of interest in another direction also, inasmuch as it affords an example of the origin of a giant race as the result of crossing two non-giant varieties. The F„ generation consists of 33 plants of which one was recorded as a "doubtful giant" (51/2/1). This plant yielded an F, consisting of seven plants of which five are non-giant and two are giants. Four of the non-giant F„ plants yielded F^ families which together contained 59 plants none of which are giants. The results of this experiment and those of the experiments described previously conform with the requirements of the hypothesis that floral gigantism is determined by three factors, all of which must be present in the homozygous condition for the phenomenon to be exhibited. The results now to be described require a slight modification, or rather extension, of this hypothesis. As mentioned already the " doubtful giant " (51/2/1) obtained in the F.2 of the cross Snow Drift x Snow King (Table VII, I) yields an F3 consisting of 5 non-giants and two giants. Whence it follows that 180 Gigantisni in Primula sinensis the floral habit of a plant may approach so nearly that of a giant as to be recorded as a "doubtful giant" although, as shown by its progeny, it is not pure for the giant character. TABLE VII. The Production of Giants by the Crossing of Noro-Giant Forms. I 190'j Snow Drift x Snow Kin;/^ 1910 Fi= 22 plants: uo giants recorded selfed 2 plants 1911 F„= ( 51/1 = 17 plants: no giants 51/2 = 10 plants of which 1 = (? giant) (51/2/1) selfed (? giant) and 4 non-giants 1912 F-J-- II 1909 " 1910 Fi = 1911 F2 = 1912 i^3 = 51/2/1 (fro7n {•> fiiatit) F«)= 7 plants, viz 51/1 {from noii-ijiant F.^) = H 51/fl ,, „ = 5 51/il/ „ „ =14 51/ir „ „ =27 Snow Drift x White Queen Star (Normal) 9 plants, no giant 8/2/2 = 15 plants, uo giant I 8/2/11 =1 plant non-giant <8/2/2/ll = 9 plants, no giant I 8/11 = 18 plants j 1 with giant flowers t 1 ? giant = 17 (?16) non-giant non-giant, 2 giant 59 plants : none giant 1 (?2) giant It must therefore be assumed that combinations of the factors A, B, C other than the combination AABBCC may give rise to giant-like forms. The assumption which appears to fit the facts most nearly is as follows : Of the three factors A, B, C two, but not any two, must be present in the homozygous state for the definite manifestation of gigantism. Provided that the plant have the constitution AABB, it may exhibit well-marked gigantism even though the third factor C be present in the heterozygous condition. Thus the three factorial combinations AABBCC, AABBCc, AABBcC may all produce giant-like plants, albeit the homozygous giant is recognizably more gigantic than the lietero- zygous giants. The genetical behaviour of the "doubtful " giant 51/2/1 (Table VII, I) demonstrates that it is not pure to gigantism. If there be ascribed to it a con.stitution AABBCc, it should yield an F3 of AABBcC AABBCc' 1AABBCC:2 lAABBcc. 1 Snow King has flowers of fair size {xtelUitu type) and should perhaps be classed as a semi-giant. F Kkeble 181 The first iw an undoubted giant, the last is an undoubted non-giant, the two others are of the constitution of the F^ parent, namely hetero- zygous for C, and although the parent arising in a family of smaller forms was classified as a doubtful giant, these plants now that they are seen side by side with the more massive (AABBCC) plant are thrown unceremoniously into the category of minor forms. Classified thus the F-i consists of: 1 giant : 3 non -giant in seven plants Vlo „ : 5'25 „ expected 2 „ : 5 „ found. If the ultimate object of Mendelian analysis were merely to fashion constitutions on slender experimental bases, an hypothesis such as that now in coui-se of formulation would be scarcely worth the making ; but it must be remembered that one of the prime objects of Mendelian analysis is to provide classification with more subtle methods than those on which it relies at present ; and, as is shown immediately, the hypothesis now in course of adumbration does lead to a better system of classification of the cultivated forms of P. sinensis than could be obtained by any other method whatsoever. The validity of the assumption that well-marked gigantism may only be manifested by plants which, whilst possessing a certain factor C in the homozygous or heterozygous condition, are pure with respect to the presence of the other two factors (AA) and (BB) is borne out by the results of experiment 80/07 (Table V). In this experiment a true breeding giant (AABBCC) Giant Pink was crossed with Lord Roberts Star which by reason of its delicate habit of flower may be regarded as of the constitution aabbcc. Giant Pink x Lord Roberts Star, AABBCC X aabbcc = F, : AaBbCc, and such an F^ on self-fertilization yields an F„ composed of: giant and r 1 AABBCC approximately J lAABBcC:61 non-giants giant forms I lAABBCc = in 64 plants : 3:61 = „ 211 „ 9-9 :20M actual i?; = 9 : 202. 182 Gigantism in Primula sinensis Although not directly germane to the subject of gigantism it may be recorded here that the form of inflorescence of the cultivated varieties of P. sinensis appears also to be determined by the mode of distribution of three factors in the zygote. Thus in the cross just described (Giant Pink x Lord Roberts Star) the somewhat delicate and few-flowered type of inflorescence character- istic of Lord Roberts Star disappears in the F^ generation and in the Fn generation there are produced : 212 non-"Roberts" inflorescence : 8 "Roberts": which ratio points to the oonclusion that general type of inflorescence is determined by three factors (XYZ) ; that the Lord Roberts Star type which is patently more feeble than either the sinensis or stellata types is produced in pure form only when the zygote has the constitution xxyyzz ; and that Roberts-like inflorescences are also produced in plants of the constitutions Xxyyzz and xXyyzz. If this be so then in 64 F., plants there are to be expected : 3 Roberts : 61 non-Roberts and in 211 plants Of) „ : 201 1 whereas 8 „ : 203 „ were found. The finer details of form of inflorescence, length of peduncle, length of pedicel etc., appear also to be determined by Mendelian factors. The evidence in support of this statement must be reserved for a further communication, although the fact, that the Mendelian method may aid the plant-breeder to trim up a plant to almost any desired form — to straighten the leaves, to elongate the pedicels, to lower or heighten the inflorescence — deserves to be brought to the attention of professional plant-breeders. To return to the subject of gigantism : the hypothesis that this phenomenon depends on not less than three factors drives us directly to the conclusion that the classification of varieties of P. sinensis into giant and non-giant forms is illusory. For it is a necessary corollary to that hypothesis that the mode of distribution and combination of these factors must be very different in the different races. In other words the conclusion is inevitable that, as is notoriously the case in other cultivated plants, P. si7iensis must contain not only giant and dwarf strains but also semi-giant races. Further the hypothesis enables us to understand our failure to recognize, previous to Men- delian experiment, the existence of such diverse races. For with three factors concerned in the determination of stature the number of F. Kekble 183 intermediate forms must oecessarily be large, and these forms must also produce the illusion of a continuous series rather than of a series made up of a large but definite number of forms, each of definite constitution and each therefore distinct from the others in genetical behaviour (c/. Nilsson-Ehle (1909) and Baur (1911)). Mendelian analysis thus leads to the recognition that just as with antirrhinums, peas, sweet-peas and hosts of other cultivated plants, so with Primula sinensis we have to deal with giants, dwarfs and middle races. The case already described in which giants arose as the outcome of the mating of non-giants is at once intelligible when this fact is grasped. Two instances of the appearance of giants in this manner are recorded in Table VII. In one, Snow Drift x Snow King a doubtful (i^„) giant yielded an F.. of 5 non-giant : 2 giant ; in another, an F-i from Snow Drift x White Queen Star, the ratio is 16 (? 17) non- giant : 1 (? 2) giant. Now although both Snow King and White Queen Star are alike in their stellata flowers and steUata habit of inflorescence, the flower of Snow King is distinctly larger and the petals more massive than is the case with White Queen Star. In other words Snow King is a semi-giant. It must therefore contain more of the factors for gigantism than are borne by White Queen Star. By ascribing factorial formulae consistent with their apparent con- stitutions 10 the varieties Snow Drift, Snow King and White Queen Star it is possible to account for the several results obtained by crossing each of the two latter varieties with the former variety. Thus and by way of illustration only, if the constitution of Snow Drift be aabbCC and that of Snow King be AABBcc then Snow Drift x Snow King = aabbCC x AABBcc and F, = AaBbCc F.2='3 giant and giant-like : 61 non-giant = 3 „ :61 as compared with 1 „ : 15 „ found = 4 „ :60 „ A further point worth bearing in mind is that the conception of three factors admits of the explanation of minor but constantly recurring variations in shape and size of flower. For in a family which lacks the Journ. of Gen. n 13 184 Gigantism in Primula sinensis C factor, one of the other factors may be present in homoz^'gous condition in some members and in heterozygous condition in others. In such a family, which can never produce a giant form, the constituent individuals may be characterised according to their respective factorial constitutions by different modes of growth of the corolla and other parts. In the variety Mont Blanc Star for example there are to be met with constantly plants which bear smaller flowers than the type. These peculiar flowers are characterised not only by their smaller size but also by the fact that the basal parts of the petal-lobes are more fused with one another — approaching slightly to gamopetaly — than are the corresponding parts of the flowers typical of the variety. The assumption of the existence of three factors for size of corolla throws light on this phenomenon. Lacking altogether one of the three factors for gigantism the variety Mont Blanc Star cannot throw giants but if its constitution be AaBBcc it may throw both AaBBcc and AABBcc forms, the former in larger numbers than the latter. If the AABBcc form differs, as differ it must, from the AaBBcc form it is described as a fluctuation. In other words fluctuations or minor variations may owe their origin to the hetero- zygousness (for one or more factors) of a factorial complex which is completely lacking in one factor essential for the production of a given Mendelian character. On the assumption that growth factors may condition cell chemistry this hypothesis of the origin of fluctuations may be found to supply the key to an explanation of the facts discovered by H. E. and E. Frankland Armstrong (1912) with respect to the sporadic dis- tribution of cyanophoric glucoside in herbage plants, such as Lotus corniculatvs. Their studies have brought to light the interesting fact that the glucoside may be present in one plant or group of plants and absent from another, and although it may be that climatic conditions may play a part in the phenomenon it seems also probable that this fluctuation is dependent on the genetic constitutions of the individual plants. Again it will be at once evident that the cases enumerated in Table IV, in which giants appear in i^,, are susceptible of explanation on the hypothesis which has been put forward. Thus Crimson King (see Table IV) is itself a fairly massive plant and may be supposed to contain two of the three growth factors. Hence when crossed with a giant it gives an F^ which the expert describes as semi-giant and an F„ (Table IV) composed of IS giant : 5 non-giant. Thus : F. Keeble 186 AABBcc X AABBCC yields i^i = AABBCc F2, of 3 giant and giant-like forms : 1 non-giant = in 18 plants : 13'5 giant : 4-5 non-giant as compared with 13 ,, : 5 „ found (Table V). In supposing that plants which, in F-^, were ranked as semi-giants are liable to be classed with giants in F„ no violence is done to probability; for in the first place the judgment is a rough judgment and in the second place the habit of inflorescence in F^ is apt to be free, and the flowers borne in such an inflorescence are less likely either to appear or to be gigantic than those which are borne on a more massive flower-stalk. Indeed the records of the behaviour in sub- sequent generations of plants recorded as giants show that not all plants to which gigantism is ascribed with confidence prove to be pure to that character. Finally with respect to the Mendelian phenomena of gigantism it appears reasonable to conclude that gigantism in P. sineiwis depends for its full expression on the simultaneous presence of three factors : that pure giants are homozygous for these factors ; that giant-like forms occur when the plant is heterozygous for the C factor ; and that an intergrading series of semi-giant races occurs in which the grades are represented by appropriate combinations of factors and their " absences." Theoretical Considerations. Numerous considerations, some of no small interest and importance, arise out of the results which have been described in the previous sections ; but of these considerations only few can be discussed in the present paper. First among them is the question concerning the origination of Giant White Queen Star. Is the fact that it arose in course of "selection" of flowers with supernumerary petals a mere coincidence or did the selection process play any part in the liberation of the giant ? If the hypothesis on the nature of fluctuation (see p. 184) be accepted it is evidently susceptible of application in the present case. For a form of P. sinensis of the type of constitution AaBbcc though, for lack of the C factor, it may not produce giants, may produce gametes of various constitutions and these in turn combining in the various ways open to 186 Gigantmii in Primula sinensis them may give rise to zygotes characterised by minor peculiarities which are the outcome of the several constitutions. However this may be, the origin of Giant White Queen Star appears to provide an example of the appearance of a "new," dominant character and is noteworthy because of the small number of cases in which this form of evolution has been observed. For, as is well known, the " dropping out " of a factor is common enough in the descent by reduction which cultivated and wild plants are undergoing ; whereas the number of known examples of tiio appearance of new dominant characters (Punnett, 1911) is much fewer and none is known in which the phenomenon has, as it were, been witnessed in a pure strain. Second, the complete infertility of the giant when crossed either with its parent or with other strains and its original relative infertility on self-fertilization are remarkable and suggestive facts. Third and last : the phenomena of gigantism appear to have a bearing on those which concern the origin and nature of certain of our cultivated plants such as fruit trees and .shrubs. Thus a culti- vated variety of apple, pear or plum is evidently a giant with respect to its fruit. It may well prove that this cell-gigautism is the origin of all the differences between the large and luscious fruit of the cultivated apple and the astringent puny fruit of the crab. Alter the size of the cell-laboratory and the operations of that laboratory are altered. Events which mark the waning of the life of the small and rapidly maturing cell of the crab may never — for reasons of time or space — occur in the large and slow growing cell of the apple. The character of astringency would seem to have been lost by the dropping out of a factor for that character ; whereas on the view now presented it is only lost because under the new conditions of growth the character cannot appear. How far all or most Mendelian characters depend directly or indirectly on such growth acceieratory and growth inhibitory factors must be left ftir subsequent consideration. Summary. 1. A giant form of White Queen Star originated from a normal strain of known pedigree. 2. The giant arose in the course of selection-experiments made with plants possessing flowers with supernumerary petals. 3. Histological comparison indicates that the gigantism of the mutant is due to that of its cells. F. Keeble 187 4. The giant arose suddenly and breeds true. 5. It is now moderately fertile with its own pollen but proves absolutely sterile when crossed with all other varieties (including the parent form) of P. sinensis. (). Gigantism in P. sinensis is due to three factors and the character is dominant to normal-character. 7. Owing to the number of factors involved in the production of the character of gigantism numerous semi-giant races exist. These races intergrade one with another and hence their existence is not generally recognized. 8. Giants which breed true may be produced by crossing non- giant races of P. sinensis. 9. Fluctuating variations may owe their origin to the heterozygous state of one or more factors in a form from the genetic constitution of which is lacking entirely one of the factors for the production of a Mendelian character. In conclusion, the author has pleasure in expressing his thanks to Miss C. Pellew for her assistance during the early part of the experiment, and to Mr G. Coomhs both for his kindness in drawing the figures in the text and for much other help. The author has also to add that a portion of the expense incurred in the plant-breeding experiments has been met by a grant from the Royal Society. REFERENCES TO LITERATURE. 1901. De Vries, Hdgo. Die Mutationstheorie. Leipzig, Bd. i. 1909 a. Bateson, W. MendeVs Principles of Heredity, p. 19. 1909. Cambridge University Press. 1909 b. Bateson, W. Op. cit. "Translation of experiments in Plant Hybridiza- tion." By Gregor Mendel, p. 337. 1909. 1909. Gates, R. R. "The Stature and Chromosomes of Oenothera gigas, de Vries." Archiv filr Zellforschwig, Bd. in. Heft. 4. 1909. Gregory, R. P. "Notes on the Histology of the Giant and Ordinary Form of Primula sinensis." Proc. Camb. Phil. Soc. xv. Pt iii. 1909. 1909. Nilsson-Ehle, H. Krev.zungsiintersuchungen an Hafer und Weizen. Lund. 4. S. 122. 1909. 1910. Keeble, F. and Pellew, C. "The Mode of Inheritance of Stature and Time of Flowering in Peas {Pisum sativum)." Jmirn. of Genetics, i. 1910. 188 Gigantism, in Primula sinensis 1911. Badr, E. Einfuhrung in die experim&iitelle Vererbungdehre. Berlin (Born- traeger). 1911. 1911. Gilford, Hastings. The Disorders of Post-natal Growth and Development. London. Adlard and Son. 1911. 1911. Gregory, R. P. "Experiments with /"nwiMte si«e?iszls." Jown. of Genetics, I. 1911. 1911. Pdnneit, R. C. ilendelisin. (Chap, vii.) London. Macmillan and Co. 1911. 1912. H. E. and E. Frankland Armstrong. Herbage Studies L Lotus cornieidatus a Cyanophoric Plant. Proc. Roy. Soc. B. 84. 1912. EXPLANATION OF PLATE XL Fig. 1. White Queeu Star normal variety. Fig. 2. Giant White Queeu Star — a mutant from the normal variety. JOURNAL OF GENETICS, VOL. IL NO. 2 PLATE XI THE CAMBRIDGE UNIVERSITY PRESS BULLETIN - No. XXVI April XXIX. MCMXII Notes on books published at the Cambridge University Press Fetter Lane, London, E.C. C. F. Clay, Manager CONTENTS Primitive Christian Eschatology Christian Epigraphy . Caesar in Britain and Belgium An Enghsh-Greek Lexicon Thucydides : Book IV A First Year Latin Book A Short Syntax of New Testament Greek Cambridge EngHsh Classics : Sidney's Arcadia VVidsith Cambridge History of English Literature. Volume VIII A First German Book . . . ■';■'.'■' . Nmeteenth Century Essays ... Catalogue of the Acropolis Museum. Volume I Themis ........ Prehistoric Thessaly ...... The Early English Dissenters .... Foreign Companies and other Corporations A History of the American Bar Differential Geometry ..... A .Shorter Geometry ..... Notes and Answers to A Shorter Geometry Principia Mathematica. Volume II An Elementary Treatise on Statics . Cambridge Manuals ..... Cambridge Geographical Text-Books Physical Geography for South Africa Cambridge County Geographies Byways in British Archaeology The Heroic Age ...... English Provincial Printers .... The Scottish Liturgy ..... Permissible Additions to and Deviations from the Service Books of the Scottish Church as Canonically Sanctioned The Odes and Psalms of Solomon : Syriac Text Mar Shimfln, Catholicos of the East Hoiae Semiticae, No. IX .... The Revised English Grammar The Revised English Grammar for Beginners . Nathan der Weise ...... The Study of 'limber and Forest Products in America Catalogue of MSS. in the Library of Corpus Christi College. Pt. VI Biographical History of Gonville and Caius College. Vol. IV The Works of John Caius, M.D. . Biometrika. Vol. VIII, Parts 3 and 4 . The British Journal of Ps)chology. Vol. IV, Parts 3 and 4. The Journal of Agricultural Science. Vol. IV, Part 3 . The Journal of Genetics. Vol. I, No. 4 and Vol. II, No. i The Journal of Hygiene. Vol. XI, No. 4 and Plague Supplement I The Journal of Physiology. Vol.XLIII, No. 6; Vol. XLIV.Nos. i and 2 The Modern Language Review. Vol. VII, Nos. i and 2 Parasitology. Vol. IV, No. 4 ; Vol. V, No. i . . . . English Composition ......... German Grammar .......... 31 32 32 32 32 Primitive Christian Eschatology. Being the Hulsean Prize Essay for 1908. By E. C. Dewick, M.A., Tzitor and Dean of St Aidans College, Birkenhead and Teacher in Ecclesiastical EI istory in the University of Liverpool. Demy 8vo. pp. xx + 416. Price \os. 6d. net. Extract from the Introduction Eschatology, dealing as it does with the unknown future, possesses at all times a peculiar fascination for the human mind It is indeed true that during the latter part of the nineteenth century, the Doctrine of the Last Things seemed to be receding into the background of Christian teaching... but in the last few years this very doctrine has been thrust forward into great prominence by the efforts of a certain school of thought in Germany, who maintain that the very core and essence of Christianity, as taught by Jesus Christ, lay in his eschatological teaching... and the whole question of the Christian Doctrine of the Last Things stands in the forefront of modern theological problems. The method which has been pursued in this essay is as follows : — In Part I the main features of Old Testament Eschatology are discussed. In Part II we have dealt with the writings of later Juda- ism and especially the apocalyptic literature. Part III deals with the most important section of our subject — the eschatology of our Lord. In Part IV we have considered the eschatology of the apostles. Part V treats of Christian Eschatology in the first and second centuries. In Part VI we have endeavoured to indicate the evidential value of Primitive Christian Eschatology, and to point out some of the ways in which it confirms the claims of Christ's Religion. % ■ 1—2 Christian Epigraphy. An Elementary Treatise, with a col/ection of ancient Christian inscriptions mainly of Roman origin. By Orazio Marucchi Professor of Christian Archaeology in the Royal University of Rome. Translated by J. Armine Willis. Pott 8vo. pp. xii + 460. With 30 plates. Price 7.?. 6d. net. Extract from, the Prefatory Note by Dr M. R. Ja7nes Dr Marucchi's work is primarily concerned with the in- scriptions of Rome, though important monuments from elsewhere find a place in it — The author's plan has been to select from the bewildering mass of extant material sufficient specimens of all the main classes of Christian inscriptions to familiarise the reader with the current formulae. ..to interpret methods of dating and to appreciate the bearing of the monu- ments upon history. Under such guidance it becomes possible to realise the importance, the interest, and the beauty of these early documents. Caesar in Britain and Belgium. Simplified Text with Introduction, Notes, Exercises and Vocabulary by J. H. Sleeman, M.A., Late Eellow of Sidney Sussex College, Cambridge and Lecturer in Latin in the University of Sheffield. Pitt Press Series. Extra fcap. 8vo. pp. xxx+123. With 12 iUustrations and a map. Price i.r. isd. Extract from the Preface The text of this little book, which is based on Caesar, B. G. IV. 20 — 38, and v. i — 23 and 38 — 52, presents an attempt to follow out the recommendations of a Committee of the Classical Association and to provide a continuous Latin narrative, not too difficult for pupils who have learnt Latin for only a year. Long sentences have been broken up or curtailed. ..and much of the early part of the selection has been entirely rewritten What little oratio obliqua the text contains is of the simplest kind The notes are mainly grammatical... The exercises are based on the text but, it is hoped, do not follow it too slavishly. It is thought that some at least may be done viva voce in class In the introduction I have given some account of Caesar's life and of Roman military institutions. 4 Ai^ English- Greek Lexicon, with an introduction and appendices. By G. M. Edwards, M.A., Fellow of Sidney Sussex College, Cambridge. Fcap. 4to. pp. xxxii + 332. Price ys. 6d. net. Extract from the Preface In this book my chief endeavour has been to interest the student in the wonderful riches of the Greek language, its idioms and its vocabulary. I do not advocate the constant use of the "English-Greek" in composition at school or at the University... but I have found, in the course of a long experience, that the entire absence of this aid often produces a meagreness of language which is most discouraging to the writer. It is a characteristic of the young student who has any feeling for style to revel in fine words. CONTENTS OF INTRODUCTION I. Prose and Verse Vocabulary II. Note on the Greek of Herodotus III. The dialect of Tragedy IV. The importance of Aristophanes for Greek lexicography V. Thucydides VI. The Attic Orators VII. Plato VIII. Xenophon a bad authority for Attic IX. The new Hellenica X. Notes on development in the Greek language XI. Ornate equivalents XII. The Athenian ideal illustrated by the vocabulary XIII. Notes on Quantity Athenaeum. The work of a sound scholar, and, as its 320 pages supply a good grounding in vocabulary, separating verse and prose, it is likely to be adopted for the use of young students. ...The Introduction is more ' fitted for advanced Grecians than for beginners. It is, in fact, a sketch of great interest, depending on fine scholarship, and affording an admirable insight into the wonderful grace and variety of Greek. Thucydides : Book IV, Edited, with an introdjictton and notes, by A. W. Spratt, M.A., Fellow and Tutor of St Catharine s College, Cambridge. Pitt Press Series. Extra fcap. 8vo. pp. xx + 448. Price i>s. 5 A First Year Latin Book. By John Thompson, M.A., formerly Scholar of Christ's College, Cambridge, Head Master of the High School, Dublin. Extra Fcap. Svo. pp. xviii + 227. Price 2s. Extract from the Introduction This book is an attempt to meet the requirements of the first year of learning Latin, as prescribed by the Report of the Curricula Committee of the Classical Association. The following points should (according to the Report) be borne in mind in a book containing work for the first year: (i) Vocabulary: At least 500 of the commonest words should be mastered during the year. (2) Repetition: Words and forms should be frequently repeated until the learner is thoroughly familiar with them. (3) Methods of teaching: A variety of methods should be used such as {a) Oral question and answer in Latin, {b) Repetition of sentences with changes of tense and other variations, (^c) Conversion of simple English sentences into Latin, (d) Comparison of Latin words with PVench and English derivatives. In this book the different forms of the simple sentence are treated first side by side with the development of the regular accidence, and then some of the commonest and simplest forms of subordinate clauses with the indicative and subjunctive moods The chief uses of the cases are also introduced, and the principal prepositions. The accidence covers the five regular declensions of nouns, the declensions of the adjectives and pronouns, the formation of adverbs, the numerals, the four conjugations of the regular verb in the active voice throughout, and in the present passive (excluding all the participles), and the conjugation of suin, the -io verbs like capio, and the chief irregular verbs. A Short Syntax of Ne-w Testament Greek. By Rev. H. P. V. Ntmti, M.A., St Johtis College, Ca?nbridge, sometime Lecttirer at St Aidans College, Birkenhead. Crown Svo. pp. xii + 140. Price is. bd. net. 6 Sir Philip Sidney. The Countesse of Pembrokes Arcadia. Edited by Albert Fcuiller-at, Professor of English Literature in the University of Rennes. Cambridge English Classics. Large Crown 8vo. Cloth, pp. .xii + 572. Price is,s. 6d. net. (Forming Volume I of the Complete Works of Sir Philip Sidney in Three Volumes) Extract from Prefatory Note Reprints of the separate works of Sir Philip Sidney are numerous ; yet, however incredible this may seem, no complete edition has hitherto been accessible. The object of the volumes now offered to Elizabethan students is to collect all the literary productions of Sidney : The Countesse of Pembrokes Arcadia, the Poems and The Defence of Poesie as well as the Correspondence and the Political Pamphlets. I even propose to include the translations of the Psalms and of Mornay's Vdritd de la ReligioJt Chrestienne, it being possible to ascertain Sidney's share in these works In accordance with the scheme of The Cambridge English Classics, the text adopted is printed without any deviations from the original in the matter of spelling and punctuation, save those recorded in the list found on page 520. These exceptions consist of evident misprints which it has been thought useless to preserve. In the Notes, I have given the variant readings supplied by all the editions (fourteen in number) published from 1593 down to 1674. Widsith. A Study in Old English Heroic Legend. By R. W. Chambers, 31. A., Fellow and Librai'ian of University College, London. Demy 8vo. pp. xii + 263. With two maps. Price \os. net. CONTENTS I. Widsith and the German Heroic Age II. The stories known to Widsith : Gothic and Burgundian heroes III. Tales of the sea-folk, of the Franks, and of the Lombards IV. Widsith and the Critics • ' ' ' V. The Geography of Widsith VI. The Language and Metre of Widsith VII. Summary and Conclusion Text of Widsith, with Notes Appendix Maps and Index 3 The Cambridge History of English Literature. Volwvne VIII, The Age of Dry den. Edited by A. W. Wai'd, Litt.D., P.B.A., Master of Peterhouse, and A. R. Waller, M.A., Peterhouse. Royal 8vo. pp. xiv + 516. Price, in buckram ()S. net, in half-morocco 15^. net. CONTENTS CHAP. I. Dryden. By A. W. Ward, Litt.D., P.B.A. II. Samuel Butler. By W. F. Smith, M.A. III. Political and Ecclesiastical Satire. By C. W. Previte-Orton, M.A. IV. The Early Quakers. By Edward Grubb, M.A. V. The Restoration Drama. I. By Professor F. E. Schelling. VI. The Restoration Dranja. II. By Ch.^rles Whibley. VII. The Restoration Drama. III. By A. T. Bartholomew, M.A. VIII. The Court Poets. By Charles Whibley. IX. The Prosody of the Seventeenth Century. By Professor George Saintsbury, M.A., F.B.A., LL.D., D.Litt. X. Memoir and Letter Writers. By Henry B. Wheatley, F.S.A. I. Evelyn and Pepys. II. Other Writers of Memoirs and Letters. A. Other Writers of Memoirs and Letters. B. By A. W. Ward, Litt.D. XI. Platonists and Latitudinarians. By J. Bass Mullinger, M.A. XII. Divines of the Church of England, 1660-1700. By the Venerable Archdeacon Hutton, B.D. XIII. Legal Literature. I. By Professor F. J. C. Hearnshavv, M.A., LL.D. II. Selden's Table Talk. By A. W. Ward, Litt.D. XIV. Jolm Locke. By Professor W. R. Sorley, Litt.D., F.B.A. XV. The Progress of Science. By A. E. Shipley, Sc.D., F.R.S. XVI. The Essay and the Beginning of Modern English Prose. By A. A. Tilley, M.A. Bibliographies. Table of Principal Dates. Index of Names. CAMBRIDGE HISTORY OF ENGLISH LITERATURE Volume VIII PRESS NOTICES Standard. The Master of Peterhouse and his colleague, Mr Waller, are to be congratulated on the steady progress of the Cambridge History oj ■ English Literature. The first volume was published in 1907 and now we are confronted with the eighth. They have differed considerably in literary merit, but that is perhaps inevitable when the services of a syndicate of writers have been called into requisition. It is a pleasure to be able to add that the present instalment of a great task is marked by distinction of style and critical discrimination both as regards men and movements in English letters.... The whole volume is alive with interest and gives many clues to the interpretation of the wonderful march of thought in almost every direction "which rendered memorable the period from the Restoration to the death of William III. The volume is equipped with admirable bibliographies, a table of principal dates, and an exhaustive index. It deserves the welcome which students reserve for a really important contribution to literary criticism. Daily Telegraph. The eighth volume of this fine work deals with "The Age of Dryden," a period... that to the student is full of deep interest. ...The new volume of the History is in every way worthy of the earlier ones — each successive instalment the more fully impresses upon us the valuable work which Dr A. W. Ward and Mr A. R. Waller are doing. When completed, the Cambridge History of English Literature will be some- thing far more than a work of reference, it will be at once a body of authoritative criticism and exposition for students and a work in which every reader with a true liking for literature will find inexhaustible delight, for the "readability" of the volumes is one of their marked character- istics. Scotsman. In its eighth volume the Cambridge History of English Literature, a work which has already established its position as the best existing academic text-book of its important subject, goes on its way with conspicuous success, following out in the marshalling of new material the same plan as has proved so effective in preceding volumes. The bibliographies, which form so serviceable a part of this history for readers who wish to attack original texts in the best possible form, have never been better done than in the present volume, the bibliography of Dryden by Mr H. B. Wheatley being especially noticeable.... The volume is a full and interesting compendium of what modern learning has to teach about the progress of English letters in the forty years that followed the Restoration. Contemporary Review. The volume of the Cambridge History of E?iglish Literature just issued, entitled The Age of Dryden, is one of curious fascination, and has a peculiar value to the student of literature, treating as it does of a period wiih which students are less familiar than they might he, a period which represents transition rather than decline, a period in which we see the awakening of reality in thought accompanied by the decay of reality in literature. It is these transition periods that are of chief importance to the student of literary evolution. 9 i-s A First German Book on the Direct Method. By G. T. Ungoed, M.A., late Exhibitioner of Trinity College, Cambridge, Assistant Master at Acton Coimty School. Large Crown 8vo. pp. viii + 177 (or 136 without vocabulary). Price 2s. bd. Extract from the Preface This book is an attempt to provide an easy course of instruction for pupils who begin the study of German at an early age. It is written entirely in German and contains a series of graduated lessons with questions and exercises, phonetic transcriptions of the first eleven lessons and a brief summary of grammar. Alethod. The work is planned for use on the direct and oral method. Subject Matter. The text has been chosen to teach a vocabulary dealing mainly with the immediate surroundings of the pupils. Pronunciation. The pronunciation adopted is that pre- scribed by the stage conference and expounded in the works of Siebs and V^etor. Plan of the book. The frame-work of the book is the series of class-room lessons introducing fresh grammatical phenomena, followed, where possible, by a rhyme and an anecdote. Nineteenth Century Essays. Edited with an introduction and notes by George Sampson. Pitt Press Series. Extra fcap. 8vo. pp. xii-|-227. Price zs. CONTENTS Carlvle, On History Macaulay, Ranke's History of the Popes Bagehot, Shakespeare — The Man Newman, Literature RusKiN, Sir Joshua and Holbein Arnold, Marcus Aurehus Stevenson, .4 Penny Plain and Twopence Coloured 10 Catalogue of the Acropolis Muse-um. Volume I, Archaic Sculphire. By Guy Dickins, M.A., Fellow and Lecturer of St fohns College, Oxford ; sometitne Craven Fellotv and Student of the British School at Athens. Crown 8vo. pp. viii + 293. With numerous illustrations. Price \os. 6d. net. Extract from the Preface The first volume of the AcropoHs Catalogue deals with the Sculptures of the period preceding the invasion of Xerxes in 480 B.C., at present contained in the first seven rooms of the museum. A number of post-Persian objects in the Entrance Hall are therefore excluded. On the other hand, to avoid subsequent confusion, No. 610 and a few heads in the wall-case in Room V are included in spite of their later date. This volume is devoted to sculpture, and therefore the architectural details at present in Room II are omitted as well as objects in terra-cotta. It is hoped that the second volume may contain the rest of the sculpture, the terra-cottas, and the architectural fragments. The order of the catalogue was at first arranged according to the position of the objects in the museum, but as extensive changes are contemplated there, I have thought it wiser to arrange the catalogue in numerical order, so that any object may be easily found in spite of any future alteration. CONTENTS Introduction §1 §2 §3 §4 §5 §6 §7 Excavations on the Acropolis The Perserschutt Chronological Study Subjects and Meaning Material and Technique The Costume of the female statues The Equestrian series Catalogue of the Acropolis Museum Index \A second volume to be issued later will complete the worM\ II 1—6 Themis. A Study of the Sociat Origins of Greek Religion. By Jane Ellen Harrison, Hon. LL.D. [Aberdeen). Hon. D.Litt. (^Durhani), ivitli an Excursus on the Ritual Forms preserved in Greek Tragedy by Professor Gilbert Murray, and a chapter on the Origin of the Olympic Gaines by Mr F. M. Cornford. Demy 8vo. pp. xxxii + 560. With 152 illustrations. Price I'^s. net. Extract from the Introdtiction The title of this book and it.s relation to my Prolcgojnena may call for a word of explanation. In the Prolegoinena I was chiefly concerned to show that the religion of Homer was no more primitive than his language. The Olympian gods — that is, the anthropomorphic gods of Homer and Pheidias and the mythographers — seemed to me like a bouquet of cut-flowers whose bloom is brief, because they have been severed from their roots. To find those roots we must burrow deep into a lower stratum of thought, into those chthonic cults which underlay their life and from which sprang all their brilliant blossoming. When in 1907 a second edition of my book was called for, its theories seemed to me already belated. My sense of the superficiality of Homer's gods had deepened to a conviction that these Olympians were not only non-primitive, but positively in a sense non-religious. If they were not, for religion, starting-points, they were certainly not satisfactory goals. On the other hand, the cultus of Dionysos and Orpheus seemed to me, whatever its errors and licenses, essentially religious. I was therefore compelled reluctantly to face the question, what meaning did I attach to the word religion ? The problem might have continued ineffectively to haunt me, and probably to paralyse my investigations, had not light come rather suddenly from unexpected quarters, from philosophy and social psychology. To France I owe a double debt, indirect but profound, and first and foremost to Professor Henri Bergson When I read his LEvolution Crdati^ice, I saw how deep was the gulf between Dionysos I 2 THEMIS— Continued the mystery -god and that Olympos he might never really enter. I knew the reason of my own profound discontent. I saw in a word that Dionysos, with every other mystery-god, was an instinctive attempt to express what Professor Bergson calls dtirde, that life which is one, indivisible and yet cease- lessly changing My second debt is to Professor Emile Durkheim. In the light of his De la Definition des Phdno- menes Religieux and other works I saw why Dionysos, the mystery-god, who is the expression and representation of durde, is, alone among Greek divinities, constantly attended by a thiasos, a matter cardinal for the understanding of his nature. The mystery-god arises out of those instincts, emotions, desires which attend and express life ; but these emotions, desires, instincts, in so far as they are religious, are at the outset rather of a group than of individual con- sciousness... These two ideas, (i) that the mystery-god and the Olympian express respectively, the one diirde, life, and the other the action of conscious intelligence which reflects on and analyses life, and (2) that, among primitive peoples, religion reflects collective feeling and collective thinking, underlie my whole argument and were indeed the cause and impulse of my book. CONTENTS The Hymn of the Kouretes — The Dithyramb, the Apu^ci/ov and the Drama — The Kouretes, the Thunder- Rites and Mana — Magic and Tabu— Medicine-Bird and Medicine-King — Totemism, Sacrament and Sacrifice — The Dithyramb, the Spring Festival and the Hagia Triada Sarcophagos— The Origin of the Olympic Games — Daimon and Hero— From Daimon to Olympian — The Olympians — Themis — Index. Athenaeum. Miss Harrison has written a work which is likely to last long as a monument both of her wide range of classical scholarship and of her sympathetic insight into primitive conditions of mind and society. It is a book not only learned but also instinct with a soul. Moreover as every notable creation must be, the book is revolutionary.... Her style of writing is so fresh and free, and she displays such a fine enthusiasm that we are carried along, and feel ourselves not wand-bearers, but Bacchi. The index is magnificent and the letterpress and numerous illustrations are in every way worthy of the Cambridge Press. 13 Prehistoric Thessaly. Being some Account of Recent Excavations and Explorations in Nortli-Eastern Greece from Lake Kopais to the Borders of Macedonia. By A.J. B. Wace, M.A., Fellow of Pembroke College, Cambridge, Corresponding Member of the Imperial German Archaeological histitute, and M. S. Thompson, B.A., Craven Fellozu in the University of Oxford, Charles Oldham Research Student of Corpus Christi Colleo-e. A Demy 410. pp. xvi + 272. With a map, 6 coloured plates and 151 figures. Price \%s. net. Extract from the Preface The present work is an attempt to collect in a convenient form all the archaeological evidence as yet available for the prehistoric period in North-Eastern Greece. Chapters I — X, which are purely descriptive, contain full accounts of our own excavations with a summary of the discoveries of others. These we hope will be of permanent value, but how far the theories put forward in the other chapters can be justified time alone can show. Our own excavations in North Greece have all been conducted under the aegis of the British School at Athens, of which we are students. A paper containing an early draft of part of Chapter I was read at a meeting of the Research Committee of' the Royal Geographical Society, and has been published in the Geographical Journal, Vol. xxxvii, pp. 631 ff Of these publications those giving reports of our excavations are super- seded by the present work, and the views expressed in the other papers are to be modified in accordance with Chapters XI— XVII and Appendix I. As regards the transliteration of Ancient Greek we have followed the system recommended by the British School at Athens. According to this all Greek words and names are preserved in the Greek forms and only those that are in corpmon use are Latinised. 14 PREHISTORIC THESSALY— Continued CONTENTS Introduction CHAP. I. The Geography of North-Eastern Greece, and the Distribution of the Prehistoric Sites II. The Principal Classes of Pottery and Celts III. North Thessaly, Rakhmani, Marmariani, Mesiani Maghula, etc. IV. South-Eastern Thessaly, Sesklo, Dhimini, Pirghos V. Central Thessaly, Tsangli, Rini VI. Western Thessaly, Tsani Maghula VII. Southern Thessaly, Zerelia, Phthiotic Thebes, etc. VIII. The Spercheus Valley, Lianokladhi IX. Boeotia and Phocis X. The Mycenean Period and the Early Iron Age XI. Architecture XII. Connections with the South XIII. Connections with the West XIV. Connections with the North XV. Chronology XVI. The Prehistoric History of North-Eastern Greece XVII. Ethnological Conclusions Appendices. Table of Illustrations representing pottery. Museo- GRAPHicAL Index. Index. Afhenaeu?n. The explorations and excavations upon which Mr Wace has been employed for many years, more recently with the assistance of Mr Thompson, here find thorough and accurate publication. The records of discovery upon the various prehistoric sites are fully described and adequately illustrated, so that it is possible to estimate the evidence upon which the conclusions of the explorers are based ; and the con- cluding chapters of the book give a survey of the whole subject as clear as our present state of knowledge will allow, and an excellent and reasonable discussion of the various theories that have been held. ...The book is produced by the Cambridge University Press in a suitable form, and is a valuable contribution to our knowledge of a difficult subject. Scotsman. From the ethnological point of view the conclusions of the book have a not unimportant bearing on the vexed Pelasgian question and the chronological classification of the pottery seems to be a model of sound and careful method. The work is a distinct credit to the younger school of British archaeology, and fully merits the distinction it has received by being issued from the University Press. The printing is excellent and the numerous illustrations are highly successful, the coloured plates being particularly good. There is a first-rate index. 15 The Early English Dissenters in the Light of Recent Research (1550-1641), By Champlm Burrage, Hon. ALA. (Brown University'), B.Litt. [Oxon.). Demy Svo. Cloth. 2 vols, with lo illustrations. Vol. I, pp. XX + 380. Vol. II, pp. xvi + 354. Price 20^. net. Volume I — History and Criticism Volume II — Illustrative Documents Contents of Vol. I An Account of the printed Literature on the Subject (chiefly modern and general) with Criticisms. — Collections of printed Books and Manuscripts that should be visited in the study of early EngHsh dissenting history (with notes upon the strong points of each library). — Notes relating to the Contents of the following pages. The Anabaptists in England before 1612. — The gradual Growth of Puritanism and its Contribution to the Development of English Separatism until 1 58 1. — Robert Browne and the Organization of the first English Con- gregational Church. — The Rise of the Barrowists.— The Barrowists under the Leadership of Francis Johnson until 1597. — The Barrowists on the Continent. — Certain obscure Barrowist and Separatist Congregations between 1588 and 1641. — The Family of Love and the English Seekers. — The first two English Anabaptist Congregations and their Leaders. — The Congregation of English Anabaptists under the Leadership of Thomas Helwys and John Murton. — The English General, or Arminian, Anabaptists between 1624 and 1642. — The Rise of the Independents. — The History of Henry Jacob's Independent Puritan Congregation in London ; and the Story of the Rise of the English Particular, or Calvinistic, Anabaptists. — A Critical Examination of the Gould Manuscript. — The Churches of New England until about 1641. Appendices An additional Note concerning the book entitled, "Truth's Champion." — An additional Note relating to "A very plain and well grounded Treatise concerning Baptisme."— The latest Discovery rekiting to John Wilkinson. — The Will of Ann Robinson, Mother of John Robinson, Pastor of the Pilgrim Fathers. — Did any English General Anabaptist practise Immersion before 1641 ? Times. Mr Barrage's collection of documents is invaluable, including many pieces which have never before been published and forming a remarkably illuminating picture of the earliest English Dissenters. Athenaeum. We cannot praise too highly the industry of Mr Burrage, and we cordially congratulate him on the result of his arduous labours, which must influence all future histories of English Religion. Nor can we close our review of his volumes without making mention of the modesty with which he puts forth his facts, and the anxiety he always displays to appreciate the efforts of other workers in the same field. The volumes also contain beautifully executed facsimiles of title-pages and documents. 16 Foreign Companies and other Corporations. By E. Hilton Young, ALA., of the Inner Temple and Oxfoi^d Circuit, Barrister-at-Law, City Editor of The Morning Post. Demy 8vo. Cloth, pp. .\ii + 332. Price \zs. Extract from the Preface In the year 1904 it fell to my lot to give some consideration to the case of Risdon Iron Works v. Furness (p. 185 post). Search for authority about the knotty points involved showed how little consideration had been given to them in this country. These pages, the outcome of that search, are an attempt rather to open up the subject to discussion than to provide a full or final solution. CONTENTS , ; ■ ■; Part I -n;;: / :.:\3 :•. - The Juristic Person in Private International Law Introductory — Status — Capacity — Nationality and Domicile Part II Foreign Companies and other Corporations in English Law General Principles Status and Capacities — Residence and Domicile — Statutory Regulations — Service of Process — Liquidation — Revenue — Patents and Trade Marks — Transfer of Shares — Foreign Sovereigns, States and Governments Appendix A History of the American Bar. By Charles Warren, of the Boston Bar. Demy 8vo. Cloth, pp. xii + 586. Price 16^. net. Extract fro7n the Preface This work is not a law book for those who wish to study law, but an historical sketch for those who wish to know something about the men who have composed the American Bar in the past, and about the influences which produced the great American lawyers. Part I deals with the legal conditions in each of the American Colonies during the 17th and i8th centuries, prior to the American Revolution, the status of the Common Law as applied by the courts, the method of appointment of the courts, the leading lawyers, legislation regarding the legal profession, etc. Part 1 1 portrays the growth of the American Bar from the foundation of the Supreme Court to i860. ."• .,.,oil Lectures on the Differential Geometry of Curves and Surfaces. By A. R. Forsyth, ScD., LL.D., Math.D., F.R.S., sometime Sadlerian Professor of Pure Alathcmatics hi the U^iiversity of Cambridge. Large Royal 8vo. pp. xxiv + 526. Price 21s. net. Extract fom the Pre/ace The material of the present volume consists of the sub- stance of lectures delivered, from time to time, during my tenure of the Sadlerian professorship of pure mathematics in the University of Cambridge. The last occasion, when such lectures were given by me, was during the Michaelmas Term of 1909. As the volume does not pretend to be a complete treatise on differential geometry, and as it is restricted to the contents of my lectures, readers will find that not a few sections of the vast range of the subject are discussed only shortly and that some are left undiscussed. In lectures, my aim was to expound those elements with which eager and enterprising students should become acquainted ; they could thus, in my opinion, be best prepared for the penetrating consideration, which is suited for the private study rather than for the lecture-room or the e.xamination-room. One of my ideals, in lecturing to students, was to provide them with some of the instruments for research ; consequently this volume is mainly intended for students who, later, may devote themselves to original work. A Shorter Geometry. By C. Godfrey, M.V.O., M.A., Head Master of the Royal Naval College, Osborne, and A. W. Siddons, M.A., Assistant Master at Harrow School. Crown 8vo. pp. xxii + 302. Price is. 6d. Or in four parts: — Part I, Geometry for Beginners, is. Parts II, III, and IV, lod. each. Notes and Ansvoers to Exercises in A Shorter Geometry. By C. Godfrey, M. V.O., M.A., and A. W. Siddons, M.A. Crown 8vo. pp. iv + i6. Paper covers. Price bd. 18 Principia Mathematica. By Alfred North Whitehead, Sc.D., F.R.S., Felloiv and late Lecttirer of Trinity College, Cambridge, and Bertrand Russell, 31. A., F.R.S., Lecturer and late Fellow of Trinity College, Cambridge. Volume II. Royal 8vo. pp. xxxiv + 772. Price 30^. net. CONTENTS Prefatory Statement of Symbolic Conventions Part III. Cardinal Arithmetic A. Definition and Logical Properties of Cardinal Numbers B. Addition, Multiplication and Exponentiation C. Finite and Infinite Part IV. Relation Arithmetic A. Ordinal Similarity and Relation-Numbers B. Addition of Relations, and the product of two relations C. The Principle of First Differences, and the multiplication and exponentiation of relations D. Arithmetic of Relation-Numbers Part V. Series ^ ,..,.„. A. General Theory of Series '^ ' -■ B. On Sections, Segments, Stretches and Derivatives C. On Convergence, and the Limits of Functions An Elementary Treatise on Statics. By S. L. Loney, M.A., Professor of Mathematics at the Royal Hollotvay College ( University of London), sometime Fellow of Sidney Sussex College, Cambridge. Demy 8vo. pp. viii-f 393. Price \is. Extract from the Preface The present work is a companion book to my Dynamics of a Particle and of Rigid Bodies. It is meant to cover the usual course of Statics for Students who are reading for a Decree in Science or Engineering-, and for Junior Students for Mathematical Honours. The book starts with the elementary Principles of the subject, but a Student would profit more by its use if he had previously read some elementary work, such as my Elements of Statics. A knowledge of the ordinary processes of the Differential and Integral Calculus is assumed, and also, in soine articles, of the notions of Solid Geometry. It will be evident that, in a book of this size, many parts of the subject must be quite untouched, but I have some hopes that, within the limits I have set to myself, the book is fairly complete. 19 CAMBRIDGE MANUALS OF SCIENCE AND LITERATURE Editors: P. Giles, Litt.D., Master of Emmanuel College A. C. Seward, M.A., F. R.S., Professor of Botany in the University of Cambridge The following volumes, price is. net each in cloth, and 2s. bd. net in lambskin, will shortly be added to the series : The Ballad in Literature. By T. F. Henderson. The Troubadours. By t lie Rev. H.J. C/iaytor, M.A. Goethe and the Tvuentieth Century. By Prof. J. G. Robertson, HI. A., Ph.D. Life in the Medieval University. By R. S. Rait, M.A. A History of Civilization in Palestine. By Prof. R. A. S. Macalister, M.A., F.S.A. Ancient Assyria. By the Rev. C. H. W. Johns, Litt.D. Methodism. By the Rev. H. B. Workman, D.Lit. Rocks and their Origins. By Prof. G. A.J. Cole. The Origin of Earthquakes. By C. Davison, Sc.D. Spiders. By C. JVarburton, M.A. The following volumes have already been published : The Coming of Evolution. By Prof. Scotland. By the Rt Hon. the Lord J. W. Judd, C.B., F.R.S. BalfourofBurleigh,K.T.,G.C.M.G. Heredity in the Light of Recent English Dialects from the Eighth Research. By L. Doncaster, M.A. Century to the Present Day. By The English Puritans. By the Rev. the Rev. Prof. W. W. Skeat, John Brown, D.D. Litt.D., D.C.L., KB. .4. The Idea of God in Early Religions. The Administration of fustice in By Dr P. B. Jevons. Criminal Matters (in England and Plant-Animals: a Study in Symbiosis. Wales). By G. Glover Alexander, By Prof F. W. Keeble, Sc.D. M.A., LL.M. Cash and Credit. By D. A. Barker, An Introduction to E.xferi mental IC.S. Psychology. By Dr C. S. Myers. The Natural History of Coal. By The Ground Plan of the English Dr E. A. Newell Arher. Parish Church. By A. Hamilton Early Religious Poetry of the Hehrivs. Thompson, M.A., F.S.A. By the Rev. E. G. King, D.D. The Historical Growth of the English The History of the English Bible. Parish Church. By A. Hamilton By the Rev. John Brown, D.D. Thompson, M.A., F.S.A. Plant- Life on Land. By Prof. P". O. Aerial Locomotion. By E. H. Harper, Boiver, Sc.D., F.R.S. M.A., and Allan E. Ferguson, B.Sc. An Historical Account oj the Rise and Electricity in Locomotion. By A. G. Development of Presbyterianism in Whyte, B.Sc. 20 CAMBRIDGE MANUALS OF SCIENCE AND LITERATURE Volumes already published (continued) New Zealand. By the Hon. Sir Life in the Sea. By James Johnstone, Robert Stout, K.C.M.G., LL.D., B.Sc. and J. Logan Stout, LL.B. {N.Z.). The Moral Life and Moral Worth. King Arthur in History and Legend. By I'rof. Sorley, Litt.D., F.B.A. By Prof W. Lrwis Jones, M.A. The Migration of Birds. By T. A. Early Religious Poetry of Persia. Coivard. By the Rev. Prof. J. Hope Moulton, Earthworms and their Allies. By D.D., D.Theol. {Berlin). F. E. Bcddard, M.A., F.R.S. Greek Tragedy. By /. T. Sheppard. Prehistoric Man. By Dr W. L. H. M.A. Duckivorth. The Wanderimrs of Peoples. By Dr The Modern Locomotive. By C. A. C. Haddon, F.R.S- Edgar Allen, A.M.L.Mech.E. Links with the Past in the Plant- The Natural History of Clay. By World. By Prop. A. C. Seward, Alfred B. Scarle. F.R.S. Primitive Animals. By Geofirey Smith, M.A. EXTRACTS FROM PRESS NOTICES Athenaeum. The five new volumes comprised in this issue maintain the high standard set by their predecessors, and bring the total number puMished to date up to thirty-two. The volumes on Migration of Birds and Earthworms each contain new material based upon the observations of the authors. Mr Allen's book — the third in the series on Locomotion — is exceptionally well-illustrated, and, while mainly devoted lo ihe actual '' working of the locomotive, contains an exciting chapter on ' Performance :; and Speeds.' In the Natural History of Clay Mr Searle has a subject with many aspects, but makes them all interesting. Finally, in Dr Duck- worth's book we have a careful study of the relics of our ancestors, giving up-to-date results of the work of the leading investigators. Spectator. A very valualile series of books which combine in a very happy way a popular presentation of scientific truth along with the accuracy ot treatment which in such subjects is essential. High among them for importance of subject and for thoroughness we should rank Prehistoric Man, by W. L. H. Duckworth. The descent of man from the ape is a theory which does not seem to gain ground ; many thii gs seem to point to "a greater antiquity of the higher type of human skeleton. "...A very interesting volume is The Migration of Birds, liy T. A. Coward, with its curious demonstrations of the mechanical side of the sulject. Observer. A series notable alike for quiet scholarship and simplicity of statement.... The foitnat of this library is most tasteful, the volumes are written by experts who know their subjects well enough to exen ise easily the art of compression without loss of limpidity, and the price of each book is readily within reach of any book-laiyer. 2 1 CAMBRIDGE GEOGRAPHICAL TEXT-BOOKS General Editor: G. F. Bosworth, F.R.G.S. Crown 8vo. Bound in Cloth. Junior: By A. JOUDAN, M.Sc. {In preparation) Intermediate: By A. J. DiCKS, B.A., B.Sc. {Noiv ready) Senior: By G. F. BOSWORTH, F.R.G.S. {In preparation) The Cambridge Geographical Text-books, a series of three volumes planned on the concentric method, are now in course of publication. They will be so graded as to cover the whole course of geographical instruction, and each book will show a proper appreciation of the principles which should form the basis of a good text-book. The books are to be provided with numerous illustrations and diagrams of various kinds. The maps are of a special character and show features not usually found in the school atlas. There will be no attempt to supply ordinary topo- graphical maps, as it is felt that students should always use a good atlas with the text-books. Photographic illustrations showing important typical scenery will also be freely used, for it is now generally recognised that this feature, though some- what novel in English text-books, is of considerable and increasing importance. The books, written by practical teachers, will be found of value in preparation for the various University and Govern- ment examinations in general and for Local examinations in particular ; and for this purpose each volume will contain a useful selection of exercises and questions based on the text or from those set at various competitive examinations. Intermediate Volume. By A.J. Dicks, B.A., B.Sc. Crown Svo. pp. xii-(-362. With 84 illustrations, maps, and diagrams. Price 3^. Extract from the Preface This text-book of Geography aims at presenting the main features of the subject in a manner suitable for pupils in the middle forms of secondary schools, the ground covered being approximately that required for the University Junior Local Examinations. 22 CAMBRIDGE GEOGRAPHICAL TEXT-BOOKS— Continued The earlier chapters deal with Mathematical Geography and the various forms of land and water, so as to provide data for the elucidation of the chief factors determining climate. The importance of climatic conditions in deciding the flora and fauna of a particular region is recognised throughout the book. Brief histories of the peoples from the geographical stand- point are included, and their industrial development is asso- ciated with the underlying geographical advantages of the country. The results of the recent Census and Trade Returns are introduced, but, as a rule, statistics are sparingly used. The maps deal with climate and emphasise special features relating to rainfall, winds, etc., which would not be shown in an ordinary topographical atlas. The views illustrate physical features, important industries, and the fauna and flora of certain areas. Physical Geography for South African Schools. By Alex. L. dn Toit, B.A., F.G.S. Crown 8vo. pp. xii-l-250. With 66 illustrations and a Physical Map of South Africa (folding). Price 4^. 6d. net. Extract from the Preface This little work has been prepared in order to furnish a concise and somewhat condensed account of the processes of Physical Geography in general and applied to South Africa in particular. Although there are a number of excellent class- books on this subject, the instances and e.xamples cited in them are to no small extent European and American, and the student in a distant land is not only likely to fail in appreciating at their proper value the illustrations given, but may find some trouble and uncertainty in applying the principles of the science to his own environment. An attempt has therefore been made in the following pages to meet this natural difficulty and to assist the student in South Africa to a knowledge of the physical geography of the land in which he is residing. 23 CAMBRIDGE COUNTY GEOGRAPHIES A series of County Geographies, price i^. 6d. each, suitable for general use as hand-books to the various counties and also intended for use in schools. Each volume gives an account of the history, antiquities, architecture, natural history, industries, and physical, geological, and general characteristics of the county, and each has two coloured maps (one physical and the other geological) and a large number of photographic illustrations. The latest additions to the series are; — Breconshire, By Christopher J. Evans. West London. By G. F. Bosworth, F.R.G.S. Oxfordshire. By P. H. Ditchfield, M.A., F.S.A. The following volumes have already been published, viz. : — Aberdeenshire. By A. Mackie. Huntingdonshire. By W. M. Noble. Ayrshire. By J. Foster. Kent. By G. F. Bosworth. Berkshire. By H. IV. Monckton. Lanarkshire. By F. Mart. Buckinghainshirc. East Loudon. By G. F. Bosworth. By A. Morley Davies. The Lsle of Alan. By J. Quine. Catnbridgeshire. By Prof. T. McK. Midlothian. By A. McCalluni. Hughes and Mary C. Hughes. Monmouthshire. By H. A. Evans. Carnarvonshire. By J. E. Lloyd. Norfolk. By IV. A. Dutt. Cheshire. By T. A. Coward. Northatnptonshire. Cormvall. By S. Baring-Gould. By M. IV. Brown. Cu7nberland. By /. E. Marr. Nottinghamshire. Derbyshire. By H. H. A. Bemrose. By H. H. Swinnerton. Devonshire. By F. A. Knight and Somerset. By F A. Knight. Louie M. Dutton. Suffolk. By IV. A. Dutt. Dorset. By A. L. Salmon. Surrey. By G. F. Bos7vorth. Essex. By G. F. Bosworth. Sussex. By G. F. Bosworth. Fifeshire. By E. S. Valentine. Westmorland. By / E. Alarr. Gloucestershire. By H. A. Evans. Wiltshire. By A. G. Bradley. Hertfordshire. By R. Lydekkcr. Worcestershire. By L. J. Wills. Volumes on Dtimfriesskire, Perthshire, Renfrezvshire, and North Lancashire will be ready shortly, and volumes on the remaining counties of England, Scotland, and Wales are in an active state of preparation ; arrangements for a series of Irish geographies have also been made. Country Home. The entire series ought to find a place on every country house booksheh'. A motor tour of a county with one of these Httle volumes as companion will add enormously to its enjoyment and give an idea of the places worthy of note. 24 Byways in British Archaeology. By Walter Johnson, F.G.S., Author of Folk- Memory, etc. Demy 8vo. Cloth, pp. xii + 530. With 99 illustrations. Price \os. bd. net Extract from the Preface The following chapters, though superficially presenting the appearance of disconnected essays, really possess a strong bond of continuity. Running through the whole, implied, where not actually expressed, will be found an insistence on the principle which, in a former work, I ventured to call folk- memory. To a large extent the studies are connected with the church and churchyard. The sections which treat of pagan sites, orientation, and burial customs, embody the results of observations relating to some hundreds of buildings in all parts of England and Wales. The chapters on "The Folk- Lore of the Cardinal Points " and " The Labour'd Ox " partially, at least, break virgin soil. In "The Churchyard Yew" are set down inferences drawn from many years of investigation, the literary side of which has been rendered difficult by the existence, in various modern works, of unfounded statements and hypothetical references. The remainder of the book treats of somewhat more familiar themes, though it is hoped that fresh outlooks are suggested. Since some of the matters here brought forward have been, and indeed still are, provocative of keen, and even heated controversy, to anticipate agreement with all the con- clusions would be sheer folly. Nevertheless, it may be claimed that the facts collected have been carefully sifted, the refer- ences conscientiously verified, and the opposing theories honestly presented. CONTENTS ■ ■ ■ ■' Churches on Pagan Sites — The Secular Uses of the Church Fabric — The Orientation of Churches — The Orientation of Graves — Survivals in Burial Customs — The Folk-Lore of the Cardinal Points — The Churchyard Yew — The Cult of the Horse— "The Labour'd Ox," Athenaeum. In these 500 pages Mr Johnson has brought together a series of essays on archaeological subjects, each of which shows considerable reading and accurate research. ...The amount of information compactly presented is remarkable, and it may fairly be said that every reasoning British archaeologist ought to read these pages.... Throughout the volume is well illustrated. 25 The Hevoic Age. By H. Alunro Chadwick, Fellow of Clare College, Cambridge. Cambridge Archaeological and Ethnological Series. Demy 8vo. Cloth, pp. xii + 474. With 3 maps. Price I2J-. net. Extract from the Preface The type of poetry commonly known as heroic is one which makes its appearance in various nations and in various periods of history. No one can fail to observe that certain similar features are to be found in poems of this type which are widely separated from one another both in date and place of origin. In view of this fact it has seemed worth while to attempt a comparative study of two groups of such poems with the object of determining the nature of the resemblances between them and the causes to which they are due. The first part of the book deals with the early heroic poetry and traditions of the Teutonic peoples, more especially with those stories which were the common property of various Teutonic peoples The subjects discussed include the distri- bution of the stories and the relationship between the various versions of them, the antiquity of the earliest poems and the conditions under which they were produced. Lastly, an attempt has been made to estimate the significance of the various elements, historical, mythical and fictitious, of which the stories are composed. The second part deals with Greek heroic poetry and traditions. These relate to a period for which little or no external evidence is available ; and consequently they present many problems, the bearings of which can hardly be estimated without reference to the existence of similar phenomena else- where. In general I have followed the same plan as in the first part, and made use throughout of the results obtained there. In the third part attention has been called to the existence of a number of somewhat striking characteristics common to the two groups of poems and an attempt made to account for them. The conclusion to which I have been brought is that the resemblances in the poems are due primarily to resem- blances in the ages to which they relate and to which they ultimately owe their origin. 26 The English Provincial Printers, Stationers and Bookbinders to I557> '^^''^ Sandars Lectures, 191 1. By E. Gordon D^ijf, M.A. Oxon., sometime Sandars Reader 171 Bibliography in the University of Cambridge. Crown 8vo. pp. x+153. With 4 plates. Price a,s. net. Extract from the Preface The work of the provincial printers, stationers and book- binders forms a subject of the greatest interest, and one which has hitherto hardly received adequate attention. The presses of the two University towns, Oxford and Cambridge, have been very fully treated, and, in a lesser degree, those of St Albans and York, but with these exceptions the remaining towns have been curiously neglected, and our knowledge concerning such important printing centres as Ipswich, Worcester and Canterbury seems to have advanced but little since Herbert issued the third volume of his Typographical Antiquities over a hundred and twenty years There is still much to be learned about these provincial presses. 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Pattern Adaptation of Fishes and the Mechanism of Vision. V. On Some Facts and Principles of Physiological Morphology. VI. On the Nature of the Process of Fertilization. VII. On the Nature of Formative Stimulation (Artificial Parthenogenesis). VIII. The Prevention of the Death of the Egg through the Act of Fertilization. IX. The Role of Salts in the Preservation of Life. X. Experimental Study of the Influence of Environment on Animals. The Cambridge University Press Agents for the British Empire London, Fetter Lane Volume II NOVEMBEE, 1912 No. 3 THE CHROMOSOMES IN THE OOGENESIS AND .^.^^, SPERMATOGENESIS OF PIERIS BRASSICAE, tm\y AND IN THE OOGENESIS OF ABRAXAS GROSSULARIATA. By L. DONCASTER, M.A., Felloiu of King's College, Cambridge. rS In a recent note' on some stages in the spermatogenesis of Abraxas grossulariata I showed that there is apparently no inequality in the chromosomes of the spermatocyte divisions, corresponding with the heterochromosomes which have been found in other orders of insects. The same result has been found by others in Lepidoptera. I know, however, of no careful study of the oogenesis in this order, and since in Abraxas the sex-limited character is transmitted by the female only to her male offspring, it seemed possible that there might be inequality in the chromosomes of the eggs, corresponding with the male-deter- mining and female-determining eggs, which are shown to exist by the facts of sex-limited inheritance. In Abraxas the chromosome number is large (the reduced number being 28), and in my first attempts to investigate the subject I failed to find oogonial mitotic figures which were suitable for accurate observation. On searching for other Lepi- doptera which might provide more suitable material, I found that the Large White Butterfly (Pieris brassicae) has a much smaller number of chromosomes, with clearer mitotic figures. After following out the available stages in Pieris, the experience so gained, and especially the fact, unknown to me in my earlier attempts with Abraxas, that the oogonial divisions take place chiefly in the la^/va, enabled me to return to the study of Abraxas with more success, and to work out the earlier stages of oogenesis with some pompleteness. In the following I' ' Journal of GeHiHjps, Vol. i. p. 179. Journ. of Gen. ii 14 ■'■J 190 Cliromosomes in Pieris and Abraxas account I sliall describe first the behaviour of the chromosomes in the oogenesis and spermatogenesis of Pieris brassicae in which the phenomena are more easily followed, and then return to the oogenesis of Abraxas. Pieris brassicae. Ovaries and testes were dissected out of fresh adult larvae and young pupae (1 — 5 days) fixed immediately in Flemming's fluid, cut into sections of about Gfi in thickness, and stained with Heidenhain's iron haematoxylin. Some also were stained with Breinl's process' for comparison, especially for the study of nucleoli. A point of some interest is the fact that in adult larvae in August and September, from which the imago will not emerge until the following spring, the testes have attained their full size, and contain every stage of spermato- genesis from spermatogonia grouped around a conspicuous Verson's cell in each compartment to practically mature spermatozoa. The ovaries in adult larvae, on the other hand, are extremely small, consisting of four parallel tubes or rather columns of cells showing as yet no division into egg-chambers, and with no deposition of yolk in the eggs. That almost fully formed spermatozoa should exist in the larval testis before the six months' hibernation of the pupa is a somewhat surprising fact. Oogenesis. In the tubes of the ovary — if they may be called tubes when they are in no sense hollow — when the tube is cut longitudinally, a continuous series may be seen from early oogonia through multipli- cation stages to the earlier growth-phases of the oocytes before the deposition of yolk. Since all the stages occur in fairly regular order from the apex of the tube downwards, they are easier to follow than are the corresponding stages of spermatogenesis, for in the testis the cells are grouped in follicles which are very irregularly arranged. An examination of the stages of spermatogenesis, however, shows that they are closely similar to the series found in the egg-tubes. The apex of the tube is packed with small oogonia, of which the nucleus in the resting stage shows a faint reticulum and a conspicuous nucleolus. The latter in favourably-stained cells appears to consist of a double or bilobed chromatin mass associated with a plasmosome, or enclosed in a mass of achromatic material ; not infrequently the two halves of the chromatin mass may lie apart, and sometimes appear compound. Division figures commonly occur in gi-oups; when equatorial ' Ann. Trop. Med. and Parasitology, Vol. i. 1907, p. 470. L. DONCASTER 191 plates are seen in face, 30 chromosomes are easily counted (Fig. 1). They include eight which are smaller than the rest, and 22 larger chromosomes. The larger ones, however, are not all of exactly equal size, so that it is not easj' to separate the smallest of them from the larger members of the eight small ones. The eight small ones usually appear to be graded into two smallest, four rather larger, and two somewhat larger still, but these pairs cannot always be recognised with certainty. Pairs similar in size often but not always appear near to- gether in the equatorial plate ; this is most conspicuous in respect of the two smallest. Some figures give the appearance of an odd number of small chromosomes, but more careful study suggests that this is due to one member of a pair being seen end-wise, and the other more side- ways. I conclude therefore that there is no evidence for the existence of an unequal pair, and still less for an unpaired chromosome in the female of Pieris brassicae. Outside the circle of chromosomes in the equatorial plate, two or more small chromosome-like bodies are often visible ; their position and size usually distinguish them without difficulty from true chromosomes. Miss Cook' has described similar " chromatin granules " in the spermatocytes of Lepidoptera. After the last oogonial division, the nucleus begins to enlarge, the reticulum becomes more clearly visible, and then, apparently suddenly, the " synizesis " stage supervenes. The nucleus now contains a very fine thread or group of thi-eads, tightly coiled on one side of the cavity ; the chromatin nucleolus at this stage is single, small, with sharp outline (Fig. 2). The synizesis condition ceases as suddenly as it began, giving place to nuclei with the chromatin thread in separate segments, much inter- twined, and noticeably thicker than in the preceding stage (Fig. 3)- The transition from this to the following stages is gradual ; the nucleus enlarges, the threads become less interwoven, and finally become ar- ranged not quite regularly but approximately in a meridional manner round the nuclear membrane (Fig. 4). In the earlier stages it is im- possible to count them, but in favourable cells at this stage it is sometimes not difficult to see that there are 14 separate threads, and as the unravelling of the segments is a quite gradual process there are probably 14 at the close of synizesis, although some of the earlier cells give the impression of a larger number (possibly twice as many). The nucleolus during this pi'ocess has enlarged and finally again become conspicuously double ; occasionally the two parts are separated ; it is 1 Proc. Acad. Sci. Philadelphia, 1910, p. 294. 14—2 192 Chromosomes in Pier is ami Abraxas now more obviously composed of an achromatic sheath enclosing a double mass of chromatin. There are thus at this stage fourteen chromatin threads and a double inicleolus. The last stage represented in my series is the contraction of the threads into short thick chro- mosomes, which at the close of the process are conspicuously split (Fig. 5), so that the ordinary chromosomes are no longer clearly dis- tinguishable from the " chromatin nucleolus " which must be regarded as a double, equally paired, heterochromosome such as is described by Miss Cook {luc. cit.) in the spermatogenesis of .several species. I have not been able to determine with certainty how the doubleness of the thick chromosomes ari.ses ; in Abraxas, and also in Pygaera bucephala, the ovary of which I have examined for comparison, and in which the double chromosomes are most beautifully shown, the appearance strongly suggests that the doubleness is produced by the contraction of looped threads, which break apart at the bend of the loop and give rise to a double rod. Certain exceptional conditions should be mentioned. At various stages from the oogonia onwards degenerating cells, singly or in groups, are not infrequent, in which the nucleus develops into a more or less conipact staining mass. The same thing is not infrequent in spermato- genesis of various insects. Among cells shortly after the synizesis stage in one ovary a single nucleus is present in which, in addition to chromatin-nucleolus and plasmosome, there are about 25 short thick chromatic threads like those of the last stage in the production of the 14 double chromosomes de- sciibed above. As will be seen below in the description of Abraxas, such cells with the diploid number of shortened chromosomes are abundant in the latter insect, and appear to arise by the more or less complete separation of the chromosomes which have paired in synapsis. In Abraxas these cells probably do not give rise to eggs, but become nutritive or follicle- cells. In Pieris the nuclei of all cells at this stage, whether they will ultimately become eggs or follicle-cells, normally show the reduced chromosome-number ; the single cell found with the double number is quite exceptional. Finally it should be mentioned that in cells of the ovarian epi- thelium enclosing the developing oocytes, mitotic figures occur with many more than thirty chromosomes ; a similar reduplication of the chromosomes in the ovarian sheath appears also in Abraxas, and has been seen in other orders of insects. L. DONCASTBR 193 Spermatogenesis. The testis is divided into about three compart- ments, and at one side of each of these is a large Verson cell round which the spermatogonia are packed, not as yet visibly arranged in follicles. Here and there groups of spermatogonia may be found in division, indicating that the grouping which later shows itself by the arrangement in follicles already exists. The equatorial plates of the spermatogonia are so crowded that I have found no case in which accurate observation of the chromosomes is possible ; the best figures merely indicate that the number is about 30. A little distance away from the Verson cell, beyond the zone in which mitoses are found, the early spermatocytes, now clearly grouped in follicles, are seen to pass through phases comparable with those described in the young oocytes. Since the arrangement of the follicles is irregular, and all the cells in any follicle are nearly at the same stage, it is less easy to place the stages in their right order, but by comparison with the oocyte stages no doubt remains that the cells pass through a similar synizesis followed by a stage with long intertwined chromosomes, and then appear to contract into chromatic bodies round the nuclear mem- brane, connected by a fine reticulum. I have not found anything exactly comparable with the short double chromosomes found in the oocytes, but the last stage mentioned, which persists until the sper- matocyte is ready for division, doubtless represents it. The chromatin nucleolus is also similar to that of the oocyte at the corresponding stage. During these processes the cells enlarge considerably, and the follicles grow still more rapidly, so that each comes to contain a considerable cavity. In some testes, perhaps occasionally in all, certain follicles and their contained cells fail to grow, and when these cells come to divide in the spermatocyte divisions, the mitotic figures are irregular and very similar to the abnormal divisions which I have described in Abraxas. They are much less frequent in Pieris, and I have not followed the subsequent fate of the spermatids in this form. The normal spermatocyte divisions are remarkably regular and clear, and show with great regularity 15 chromosomes when the equatorial plate is seen in face (Figs. 6, 7). Three of these are always smaller than the rest, and usually one somewhat less small is distinguishable ; these four correspond with the eight smaller chro- mosomes observed in the oogonial equatorial plates. Side views of the metaphase and early anaphase stages of the first division show that the chromosomes divide in the heterotype manner, the separating halves being connected for a time by two strands. 194 Chromosomes in Pier is and Abraxas The second spermatocyte division is easily recognisable by the smaller size of the cells and of the chromosomes (Figs. 8, 9). Fifteen chromosomes can always be seen in well-placed equatorial plates, of which usually four, sometimes only three, and occasionally as many as five, are noticeably smaller than the rest. The two smallest are often, but not always, lying side by side. In some figures, these two small ones are very conspicuous ; in others, often in the same follicle, only one very small one is found. This led me at first to suppose that in the first spermatocyte division there must be an unequal pair of beterochromosomes such as Wilson has described in Lygaeiis and Euschistus, but if it exists, the difference in size between the two members of the pair is not sufiicient to reveal itself in a side view of the metaphase and early anaphase. I have examined many such figures with great care, and have never found a dividing chromosome in which the two halves were certainly unequal. In some figures a very slight inequality is suggested occasionally, but in others, where every chromosome is visible, no inequality can be seen. Further, the fact that there may be three or four all equally small, and in other equatorial plates in the same follicle only one (or rarely none at all) which is conspicuous by its small size, makes the interpretation of these differences as being due to unequal beterochromosomes very doubtful. It may be concluded therefore that in both sexes of Pieris brassicae the somatic number uf chromosomes is 30 ; these vary in size and include one pair which differ from the rest in the growth-phases in constituting a " chromatin-nucleolus," so resembling beterochromo- somes. The reduced number in both sexes is 15, and although there is a suggestion that the beterochromosomes form an unequal pair in the male, the evidence for this is quite inconclusive, and the appearance is very probably deceptive. Abraxas grossulariata. The material consisted of ovaries removed from larvae varying from somewhat more than half-grown up to nearly full-grown, and treated similarly to those of Pieris. The ovarian tubes are shorter, but the stages follow each other nearly as regularly as in Pieris. The oogonia contain a nucleolus more or less conspicuously double, which consists chiefly if not entii'ely of chromatin. Among the oogonia, especially near the apex of the tube, groups of cells are constantly found under- going degeneration; their number is often considerable. Oogonial mitoses, even in rather young larvae, are less numerous L. DONCASTER 195 than in Piens, and it was not easy to find examples cut so that the chromosomes could be counted with perfect accuracy. Counts were always made by drawing the chromosome group, not by eye. In the most satisfactory figures the number appears to be .56, i.e. twice the number found in the spermatocyte divisions. Two of these equatorial plates are figured in Figs. 10 and 1 1 ; the only doubt about the number 56 in these cases consists in the facts that in Fig. 10 a pair of chromo- somes (at the left upper edge, apparently consisting of a larger and smaller member) might possibly be two halves of a dividing chromo- some, but the only reason for this suggestion is that they are at slightly different levels; and in Fig. 11 the double body outside the circle at the bottom might conceivably not be a chromosome, for other stained bodies occur in the cytoplasm outside the spindle. Careful examination has convinced me, however, that in fact there are .56 in each figure. The same number has been found in three other figures in which the number 56 is quite clearly seen, and in a further three in which part of the equatorial plate was seen in the next section to the main group, so that a chromosome might possibly be cut so as to appear in two sections, although this is very improbable when they are so small. In a number of other figures it was impossible to decide with certainty between 56 and 55, and in some only 54 were clearly visible. Since in the best figures obtained there is no reasonable doubt that 56 is the true number, and since an even number is certainly present in Pieris hrassicae, it may be concluded with some confidence that in the female Abraxas grossidariata the unreduced number of chromo- somes is 56. With regard to the variety lacticolor I am less certain ; in all my figures of this form counts may be interpreted as 55 or 56, according to whether a double chromosome is regarded as one or two. As de- scribed in my paper on the spermatogenesis, the lacticolor male does not differ recognisably from the grossidariata, ^ in its chromosome group, the spermatocyte number being 28 in each. It is to be ex- pected therefore that the number in the female should not differ from that of grossidariata. That the number in lacticolor is either 55 or 56 is certain ; a final decision on the matter can only be arrived at when more material is available. It should be said that the chromosomes of the oogonial divisions in both forms are not all equal in size ; in some cases two are noticeably larger than the others, but these two are not always recognisably different from the next in size, so that accurate identification of chromosomes is hardly possible. 196 Chromosomes in Pier is and Abraxas After the oogonial stage, the nuclei begin to enlarge and pass through a synizesis stage closely similar to that of Pieris, except that the nucleolus is less conspicuous and is sometimes difficult to find. On emerging from this condition the nuclei, now considerably enlarged, contain interlaced chromatic threads, the number of which cannot be accurately determined. The nucleolus at this stage varies somewhat in appearance ; it usually consists of an achromatic mass enclosing a double mass of chromatin, but may be almost or completely divided into two parts, and each half is sometimes seen to contain a compound mass of chromatin. In the rather later stages this com- pound nucleolus, consisting of a number of globules or irregular lumps of chromatin, and usually clearly divided into two more or less separate parts, is very commonly seen in sections from which the stain is rather thoroughly washed out or which are stained with Breinl's stain (Figs. 13 a, 15«). The individual chromatin globules sometimes appear double, but I doubt whether this is more than accidental. The chromatin threads contract and thicken, but do not in general assume the meridional arrangement often seen in Pieris. They appear to become bent into loops (Fig. 12), and these shorten to form horse- shoe or even ring-like figures (Fig. 1.3). The nuclei are now so large as to extend through two sections, but careful counts show that the number of the contracted loops is not far from 27. From this stage onwards, or possibly from one somewhat earlier, a differentiation appears to set in among the cells. In the majority, the chromosomes contract still further and appear to break apart at the bend of the loop, giving rise to a double body, the halves of which are commonly completely separated, so that the nucleus contains about 27 pairs of short, thick chromosomes, and an additional larger pair apparently derived from the chromatin-nucleolus. Each member of a pair may itself show signs of doubleness, possibly owing to the precocious appearance of the longi- tudinal split of the next division, traces of which may sometimes be seen in an earlier stage (Fig. 13). In many nuclei the two members of each pair are completely separated, giving the diploid number of small irregular chromosomes scattered in the nucleus (Fig. 14). I was at first inclined to believe that the.se single chromosomes came together in pairs, giving rise to the stage in which the reduced number of doubles is seen, but a careful study of the various stages has convinced me that in the nuclei here described the paired condition precedes that with the full number of singles. The nuclei just described are the most numerous class at the lower L. DONCASTER 197 end of the egg-tube, but are not, I believe, true oocytes. Among them, fewer in number, are somewhat larger nuclei, which always lie in the middle of the egg-tube, either surrounded by those of the type just described, or extending further down the egg-tube than the latter. I believe these larger nuclei are those which will give rise to the egg-nuclei ; the kind described just previously probably belong to the cells of the egg-follicles or the nutritive cells. The large nuclei, which appear to be those of the true oocytes, contain a very large nucleolus and interlaced chromatin threads, which have not contracted into short loops. Their number is difficult to count, but appears to be the haploid number (27) rather than the diploid (o-i). The nucleolus appears to consist chiefly of chromatin ; it is either double or divided into two separate parts, and each part consists of a number of masses of chromatin apparently embedded in achromatic material, which, however, is not very easy to demonstrate. The irregularity of the chromatin masses composing the two parts of the nucleolus makes it difficult to determine whether the two parts are equal or unequal ; in some nuclei no difference in size is visible, in others one mass is certainly larger than the other. The nucleolus appears rather as a store of chromatin than as a definite chromosome. In addition to the two classes of cells described in the lower region of the ovary-tube, there are cells of varying size with many scattered chromatin granules in the nucleus. These are occasionally found in division, and show about 56 chromosomes ; if the cells described above give rise to the nutritive cells and true oocytes, these last are probably the follicle-cells. In conclusion, then, it appears that Abraxas, like Pieris, has an even number of oogonial chromosomes, with no evidence of an un- equal pair. In the early stages of the meiotic phase two of these give rise to a double chromatin-nucleolus, and the remainder undergo synizesis, from which they emerge in the haploid (reduced) number of chromatin threads. In cells which probably do not become true oocytes, these threads then become contracted into short loops, which break at the bend and give rise to the reduced number of pairs of chromosomes. The members of the pairs may then separate. In the true oocytes the bivalent threads persist to the latest stage observed — possibly till the prophase of the polar divisions. The halves of the chromatin-nucleolus, though not always identical in size, do not show any constant differences which would justify the assumption that it may be regarded as an unequally paired heterochromosome. The 198 Chromosomes in Pier is and Abraxas chromosomes in the earlier stages of oogenesis therefore do not pro- vide any visible basis for the sex-limited transmission of characters. If Spillman's suggestion be correct, that in the normal grossulariata male there are two (r-bearing chromosomes, while in the female one of these is replaced by a sex-chromosome ("X ") which does not bear G (the factor for grossulariata), this is what would be expected ; but since, in the male at least, the variety lacticolur has the same number of chromosomes as grossulariata, the G'-beariug chromosomes would have to be supposed capable of losing the factor G without becoming visibly different. Note. — Since the above was written, I find that Payne (Journ. Morphol. Vol. XXIII. 1912, p. 331) has come to conclusions closely similar to mine about both the constitution of the nucleolus and the origin of the oocytes in Reduviidae ; and Miss P. H. Dederer has published a preliminary note on the maturation of the eggs of Philo- samia cynthia {Biol. Bull, xxill. p. 40, June 1912) in which she finds no dimorphism among the egg- chromosomes. Postscript, Sept. 26, 1912. In ovaries of larvae derived from tlie 1912 pairings, although I have no perfectly trustworthy figures in individuals derived from the cross tact. X lact., I have several which show 56 chromosomes quite clearly in larvae from the cross gross. % x lact. (/. Since this cross always gives only lacticolor females, it may be concluded with confidence that the chromosome number in the lacticolor female is not different from that in the grossulariata female. EXPLANATION OF FIGURES. All the figures except Via were drawn from sections stained with iron-haematoxylin ; for all Zeiss apochromat n. a. 1.40, 3 mm. and oc. 12 were used. In figs., 3, 4, 5, 13a, l-5a the shaded area round the nucleolus represents the non- chromatic portion from which chromatin stains are easily washed out. Figs. 1 — 9. Pieris hrassicae. 1. Oogonial division, equatorial plate. 2. Synizesis stage. 3. Shortly after synizesis. The upper half of the nucleus is not included in the section. 4. Rather later stage ; complete uucleus with 14 threads and chromatin-nucleolus. 5. Contraction of threads to form double chromosomes ; only 13 of these are visible In this nucleus, the fourteenth is probably hidden by the nucleolus. L. Dongas PER 199 //I ) 200 Chromosomes in Pieris and Abraxas 6, 7. 1st spermatocyte equatorial plates ; four small chromosomes in fig. G, three in fig. 7. 8, 9. 2nd spermatocyte equatorial plates : three small chromosomes in fig. 8, only one conspicuously small in fig. 9. Figs. 10 — 1.5. Ahraxaa grossulariatii. 10, 11. Two oogonial equatorial plates, each with .56 chromosomes. 12. Oocyte after synizesis. BeduceJ number of chromatin loops. The nucleolus and a number of loops are not included in the section. 13. Slightly later stage ; not all the chromosomes are shown. (26 double chromo- somes and two nucleoli were visible in this nucleus.) 13a. Nucleolus of similar nucleus stained with Breinl. 14. Later stage, probably a nutritive cell. Somatic number of short chromosomes, most of them split, some lying in pairs. (54 chromosomes and two nucleoli were visible in this nucleus.) 15. Oocyte, at about the stage of fig. 14, with reduced number (approximately, not all shown) of chromatin threads. 15a. The two halves of the nucleolus of a nucleus in about the same stage, from which the stain is so far washed out that the chromatin threads were nearly colourless. SOME EECENT WORK ON MUTATION IN MICRO-ORGANISMS. By CLIFFORD DOBELL. Much work has been done in the last few years upon mutation" in several different groups of micro-organisms. This work has been published in many different places, and has been largely carried out in connexion with investigations of a medical nature. The records are therefore somewhat diffuse, and not always easily accessible to the biologist who applies himself mainly to the study of genetics. In the compass of the following few pages I shall endeavour to chronicle — • in a somewhat critical spirit — some of the more important observations which have been recently recorded in this branch of biology. I. Mutations in Tkypano.somes. In this first section, I shall describe some recent work upon mutation phenomena observed in several species of flagellate Protozoa belonging to the genus Trypanosoma. The mutations may be grouped in two different classes — morphological and physiological. A. Morphological Mutations. In several cases, structural modifications have been induced in Trypanosomes, and found to be permanent and transmissible for a variable number of succeeding divisions. These cases will now be described. 1 I use this term — as others have ah-eady done — to denote those heritable modifications which have been induced in various ways in various micro-organisms. I believe that a " mutation " in a Trypanosome is essentially the same sort of thing as a "mutation " in a multicellular organism. But I must also point out that I use the words "inheritance," " heritable," and similar terms in the customary manner — applying them to the trans- missible characters of such organisms as Trypanosomes, Bacteria, etc. I do not wish to assert, however, that "inheritance" in Trypanosomes means exactly the same thing as " inheritance " between parent and offspring in sexual multicellular organisms. 202 31 ut at ion in Micro-Organisnis The Trypanosomes are Protozoa possessing a very remarkable structure. It is necessary, therefore, to recall at the outset the structures present in a typical animal of this sort. This can be most clearly done with the aid of a diagram (Fig. A), an inspection Fig. A. Structure of a typical Trypanosome. (1) Trophonucleus, or chief nucleus. (2) Kinetonucleus, or smaller nucleus, in connexion with locomotory apparatus. (.3) Blephai-oplast — a minute basal granule at the root of the flagellum. (4) Undulating membrane, used in locomotion. (5) and (6) Flagel- lum — marginal (to undulating membrane) and free parts. Aiit., anterior or flagellar end. Post., posterior or aflagellar end of organism. of which will, I think, make further explanation unnecessary. The terminology of the parts is that of Minchin. To avoid any confusion I should mention that the organ which is called kinetonucleus through- out tliis paper is called centrosome by Laveran, and hlepharoplast^ by the majority of German workers. It shoidd also be added that Try- panosomes reproduce by longitudinal division — both nuclei dividing into two. I will now describe the curious structural changes which have been brought about in certain Trypanosomes, and will begin with the work of Wendelstadt and Fellmer (li)lO). It has been found by these workers that Trypanosomes — they used two species, Trypanosoma brucei and T. lewisi — which normally live in the blood of certain mammals (e.g. rats) may be inoculated into cold- blooded vertebrates and invertebrates, in which they can live for a certain time. The Trypanosomes used were from well-known strains which had been cultivated in rats and under observation in the laboratory for several years. Trypanosoma brucei was, after some difficulty, passed from the blood of rats into the blood of grass snakes {Tro}ndonotus natrix)". In the snake's blood, the Trypanosomes become smaller (Fig. B, 2), as compared with the initial forms in the blood of the rat (Fig. B, 1). > Frequently — and incorrectly — also written " blepharoblast." ' The authors refer to the snake merely as the " Ringelnatter," but presumably this animal is meant. C. DOBBLL •203 Frequently no parasites could be demonstrated microscopically in the snake's blood, although subsequent inoculation experiments proved them to be present. The small forms were apparently formed by the divisions of the original larger forms, and themselves underwent Fig. B. (1) Normal T. hrucei iu blood of rat. (2) T. brucei in blood of grass snake — eight days after inoculation. (3) T. brucei, giant form produced by inoculation from grass snake back into rat. (4) T. lewisi, normal form during chronic infection in blood of rat. (5) T. letoisi, form produced by passing the strain from rat through grass snake, then frog, and then back into rat. Fourth rat passage, five days after inoculation. [From Wendelstadt and Fellmer (1910), slightly diagrammatized.] The organisms are all drawn to the same scale, so that the differences in size are correctly shown. division. They showed a slight change in their staining capacity. When these small forms in the snake were inoculated back into rats, they became very large, thus giving rise to a race of giant Trypano- somes (Fig. B, 3). The increased size persisted for many divisions, during passage through sevei-al rats^ In later passages, however, the Trypanosomes diminished in size, and returned to their normal dimensions. Closely similar results were obtained by passing the Trypanosomes through tortoises ("europaische Sumpfschildkrote") and lizards ("graue und Smaragdeidechsen ") : but no difference in size was observed after passage through the salamander ("Erdmolche"). A temporary increase 1 When Trypanosomes (or other micro-organisms) are passed into a fresh host, or culture medium, the new race which thus arises is frequently termed a new "generation " — a vicious usage of the word borrowed from bacteriology. 204 Mutation in Micro- Organisms in the size of the Trypanosomes was also brought about by passing them through beetles {Cychrus rostratus and Ajyhodius sp.), or through a slug (Avion impiricoruvi), and then back again into rats'. Several other passages (axolotl, caterpillars, etc.) were unsuccessfully attempted. Wendelstadt and Fellmer made similar experiments with T. lewisi. They succeeded in passing this species from the rat through lizards, frogs, and grass snakes. In the cold-blooded host, no Trypanosomes could be found microscopically after inoculation : but inoculation of the blood back into uninfected rats gave rise in them to an infection with parasites of increased size''. When the normal Trypanosomes (Fig. B, 4) from the rat were passed through a snake, or through a snake and then a frog, and then back into a rat, a remarkable modifi- cation was finally produced. The Trypanosomes were not only much larger, but they were also greatly elongated at the aflagellar end^ (Fig. B, 5). No divisions were observed in these forms. Moreover, they showed certain differences in their staining properties as compared with the original forms. It may be added that no results similar to these of Wendelstadt and Fellmer have been recorded by other workers. A much more interesting — because more thoroughly investigated — morphological mutation in Trypanosomes has been discovered by Wer- bitzki (1910). In the course of some researches on the effects of certain organic dyes upon living Trypanosomes, this worker made the following observations. (The researches were carried out in Ehrlich's laboratory, on a strain of T. brucei known as " Nagana ferox," and cul- tivated in mice.) When certain dyes were injected into infected mice, the Trypanosomes (Fig. C, 2) lost their kinetonuclei (Fig. C, 1). The modified Trypanosomes were found to remain permanently devoid of this organ during subsequent divisions. They divided normally and actively, and could be passed in the usual way through other mice by subinoculations. A race of Trypanosomes with a permanent morpho- logical modification has been thus produced. The dyes used successfully ' Tlie blood contaiuiog the Trypanosomes was injected into the body of the invertebrate, which was subsequently ground up in salt solution and the licjuid so obtained injected into a rat. It is somewhat surprising that any positive results were obtained by such crude methods. Besides the Trypanosomes, very many other things must have been injected into the rats. 2 The incubation period in the rat was also found to be shortened. ' Forms similar to these are of constant occurrence during the multijilication period of normul T. lewisi in the rat (Minchin). They have been described as a distinct species (" T. longocaudense ") by Lingard. C. DOBELL 205 by Werbitzki were chiefly substances belonging to the pyronin, acridin, and oxazin groups (vide infra) — the best results having been obtained Fig. C. T. brucei, strain "nagana ferox." (1) Form without kinetonucleus, after treatment with pyronin. (2) Normal form. [From Werbitzki (1910), slightly diagrammatic.] with oxazin. The action of the dye upon the Trypanosomes is rapid. In one experiment in which oxazin was injected into a mouse on the second day after infection with the Trypanosomes, the following ob- servations were made : — Hours after injection Number of Trypanosomes of dye witliout kinetonucleus 1 — 2 Isolated specimens 4 10—12 % 6 25—30 % 8 40—50 °/o 10—12 70—80 % 24 80—90 °/o The strain containing about 80% of individuals devoid of a kineto- nucleus, when inoculated into other mice, shows a smaller — but still large — percentage of the modified organisms. By passing this strain through mice 6 — 10 times, however, and treating with oxazin each time, a strain of Trypanosomes in which every individual is devoid of a kinetonucleus has been obtained. This strain remains constant after numerous sub- sequent passages through untreated mice'. The Trypanosomes devoid of kinetonuelei are — as regards motility, general appearance and behaviour, etc. — indistinguishable from normal organisms save in this one feature. Their rate of multiplication is, moreover, unchanged. They show, however, a slight difference in resistance. ' Kudieke (1911 A) reports that one such strain has been passed through 115 mice, without any treatment, and still retains its moi-phological peculiarity unaltered. Joum. of Gen. ii 15 206 Mutation in Micro- On/anisms It should be noted that it is the kinetonucleus only which has been removed from these organisms. The blepliaroplast (end-knob, or basal granule) and the rest of the locomotory apparatus remain intact'. Werbitzki endeavoured to obtain a race of Trypanosomes vnth kinetonuclei bj- further treatment of the race from which thi-s organ had been removed. The parasites were treated with various dyes, and passed through various animals (rats, guinea-pigs, rabbits) ; but the results were not always the same. In one case, passage through 50 animals, and treatment with dyes, left the strain cpiite unaltered. In another case, however, it was found that 7 "/^ of the Trypanosomes had acquired kinetonuclei at the 16th passage: and this percentage increased during subsequent passages, until at the 27th practically every individual possessed a kinetonucleus. How the kinetonuclei were " regenerated" was not determined. Microscopically, the individuals of the new race did not differ in any way from normal Trypanosomes. But it was found that their new kinetonuclei were susceptible to the action of drugs which were without effect upon ordinary organisms. For example, the kinetonuclei in the new race were removed by the action of arsacetiu — a drug which has no action in this respect on normal Trypanosomes. An important question now arises as to the exact way in which the kinetonucleus is removed from the strain of Trypanosomes which has been subjected to the action of dyes of a certain sort. Werbitzki suggested that its disappearance might be accounted for in three different ways. First, the kinetonucleus might have been destroyed by the dye, or eliminated from the organism ; secondly, it might have fused with the trophonucleus ; thirdly, it is possible that the kineto- nucleus has really not been removed, but its apparent absence is due to the fact that it no longer takes up chromatin stains in the usual way — owing to the action of the drug — and therefore is invisible in microscopic preparations. The second and third suppositions were shown by Werbitzki to be unsupported by any direct evidence. He inclined to the supposition that the kinetonucleus had been destroyed in some way. He figured, moreover, dividing forms of the Trypano- somes in which one daughter individual contained a kinetonucleus, whilst the other contained none. The suggestion therefore seemed justified that the new race arose in this manner — by an irregular distribution of the organ during division. No definite conclusions in this respect were arrived at, however, by Werbitzki. ' This is stated on the authority of Dr v. Prowazek, to whom the strain was submitted for a careful eytological examination . C. DOBBLL 207 Kudicke (1911) made a further attempt to discover how Werbitzki's strain had lost its kinetonuclei. He says that even in normal races of Trypanosomes — that is, in organisms untreated with dyes — as many as 5 % of the individuals may lack kinetonuclei. It is therefore possible that the drug selects these organisms : they may be more resistant to the drug, and therefore survive after treatment and so give rise to the new race. Kudicke was unable, however, to discover exactly how the kinetonucleus disappeared. He found that acridin would remove the kinetonucleus from T. letvisi — in a certain percentage of cases — but here again he was unable to decide with certainty how the removal was brought about. Kudicke's work, on the whole, did not show whether the races of Trypanosomes without kinetonuclei were pro- duced by selection, by an irregular division, or in some other way. An important sequel to Werbitzki's work has been furnished by Laveran and Roudsky. Laveran (1911) obtained the " nagana ferox " and " Werbitzki " strains of T. bvucei from Ehrlich. He was able to confirm Werbitzki's observations on the structure of the individuals composing these strains. In collaboration with Roudsky (1911), he reinvestigated the action of oxazin upon T. hrucei. These workers found that the dye removed the kinetonucleus — as Werbitzki had stated. They were able to extend the investigations, moreover, to seven other species of Trypanosomes {evansi, soudanense, gambiense, dimorphon, pecorum, congolense, leivisi). In all of these, oxazin caused a disappearance of the kinetonucleus : and the peculiarity was trans- mitted hereditarily in subsequent divisions, so that strains were produced in which the individuals were — to a greater or less extent — deprived of kinetonuclei. Laveran and Roudsky (1911, 1911 A) appear to have decided how the kinetonucleus is removed. They have found that when oxazin' is injected into a mouse infected with Trypanosomes, the kinetonuclei of the latter are stained pink or violet with the dye. The rest of the Trypanosome is uncoloured, and it remains actively motile — provided that the dye is not present in such concentration as to kill. The action of the dye can be observed in a drop of infected mouse's blood under the microscope. It seems certain, therefore, that the dye has a special affinity for the kinetonucleus. It can be seen further that the kineto- nuclei which have been stained by the dye — in the living Trypanosomes — dwindle in size, and finally disappear. Laveran and Roudsky ac- cordingly believe that the dyes used have a direct and specific action ^ Similar results were obtained with acridin. 15—2 208 Mutation in Micro-On/anisms upon the kinetonucleus, which they attack and finally remove. They suggest further that the actual destruction of the kinetonucleus is brought about by autoxidation in situ. Certain experiments appear to support this view. It is known that potassium cyanide and alka- loids— when present in very small quantities — retard autoxidation processes in the tissues. Laveran and Roudsky made a number of different preparations of heavily infected mouse blood. To some they added oxazin alone : to others oxazin with minute quantities of KCN or certain alkaloids'. The results were very striking. Oxazin alone coloured and removed the kinetonuclei of tiie Trypanosomes (as usual): oxazin + KCN, or oxazin + alkaloid, did not affect the kinetonuclei, which remained quite colourless. It appears certain, from the above observations of Laveran and Roudsky, that the production of a race of Trypanosomes devoid of kinetonuclei by the action of dye-stuffs, is due to the specific action of the dye upon the kinetonucleus. The latter is attacked by the dye — as is shown by its becoming coloured — and then removed, probably by autoxidation. Laveran and Roudsky find no evidence to show that the kinetonucleus is ever removed by an irregular division — as sug- gested by Werbitzki and Kudicke. They suggest that " if in certain cases the kinetonucleus does not divide at the moment of bipartition, it is probably because it is already dead or altered" — through the action of the dye. Werbitzki (1910) found that the only difference — save as regards the nuclei — between his strain and normal 2\ brucei was that the former was less resistant to pyronin. Laveran (1911, 1911a) and Laveran and Roudsky (1911) found that the two strains differed in that the Werbitzki strain had an attenuated virulence for laboratory animals. They also found that injections of oxazin caused the appear- ance of giant forms of the Trypanosomes in infected mice (T. hrucei, T. evansi, T. soudanense). All the species of Trypanosomes without kinetonuclei appear to possess a diminished virulence. Laveran and Roudsky (1911 A), by imitating Werbitzki's procedure, have now obtained by oxazin injections a strain of T. evansi which has no kinetonuclei and is apparently fixed in this respect. It breeds true in untreated mice. From T. soudanense, however, they have only suc- ceeded in obtaining a race which — at the 50th passage — contains 66 % of individuals without kinetonuclei. ' The authors Jo not state which alkaloids they used. C. DOBELL 209 There is a point of considerable interest in connexion with the dyes which bring about the disappearance of the kiuetonucleus in Trypanosomes : for there appears to be a definite relation between the chemical structure of the dye and its action upon the Trypanosoma. Werbitzki found that those dyes which destroy the kinetonucleus are substances belonging to the pyronin, oxazin, and acridin groups (" ani- line " dyes with acid chromophores). These dyes all possess a structure which Ehrlich (1909) calls an ortlLoquinoid structure. Orthoquinoid substances possess a structure which is essentially* thus : That is to say, they consist of two benzene rings united together as shown. Dyes of the pyronin series have the general structure : c Those of the acridin series have the structure ; c H Both the pyronins and the acridins are derivatives of diphenylmethane. This is not the case with the dyes of the oxazin group, however, which have the general structure : and are diphenylamine derivatives. 210 Mutation in Micro-Organisms The orthoquinoid linkage appears to be the important thing in these substances. Those drugs with it act upon the kinetonucleus : those without it have no action. (Many dyes and other substances were tried in this respect, e.g. atoxyl, arsenophenylglycin, trypan-red, etc.) It must be noted, however, that dyes with a structure which Ehrlich (1909) terms paraquinoid {e.g. parafuchsin) also have a slight action upon the kinetonucleus. These dyes have the general structure : parafuchsin being a derivative of triphenylmethane with the structure : NH, NH^CI NH, When parafuchsin is employed in doses large enough to affect the kinetonucleus, it also injures the rest of the Trypanosome, and finally kills ii\ ' The parafuchsin-resistant strain of Ehrlich, kept at the Speyer Haus, has its kineto- nnclei intact. The strain was produced by acting upon normal T. briicei with increasingly large doses of the dye. C. DOBKLL 211 It seems legitimate to conclude, theretore, that dyes with an ortho- quinoid structure have a specific action u}]on the Trypanosome kineto- nucleus'. They fix themselves to it in some way, and bring about its disappearance. Concerning the Trypanosoraes without kinetonuclei there are but a few additional facts of importance to record. These are results of the work of Kudicke (1911a). He has not found it possible to obtain from the Werbitzki strain — either by drug treatment or transplantation into other animals — a strain in which the kinetonucleus is present once moi-e. (But compare Werbitzki, p. 206, supr-a.) From certain immunity experiments, he has concluded that the original strain of " nagaua ferox " and the Werbitzki strain derived from it, are — as regards immunity reactions — alike. Kudicke has also made some interesting observations on relapse strains of " nagana ferox." He inoculated a mouse with the strain together with trypan-blue-. Four days later, all the Trypanosomes had disappeared from the blood of the mouse. But four days after this, many Trypanosomes were found in the blood — that is, a relapse race arose. Nearly all the individuals of this race were devoid of a kinetonucleus. After passage through a second, and then a third mouse, all the Trypanosomes were without kinetonuclei. They persisted in this condition during 79 subsequent passages. An explanation of this phenomenon was not arrived at, but it seems that something different from what occurs in the case of ortho- quinoid drugs must have happened^ It is perhaps of some interest to recall here — in connexion with the experiments just recorded — certain observations which liave been made upon some flagellate Protozoa closely related to the Trypanosomes. Several observers have found occasional individuals which have lost their trophonuclei. Hartmann and Prowazek (Arch. Protistenk. X Bd. 1907) noted, for example, that 5-day cultures of the kala-azar parasite contain individuals which have lost this organ. Similarly, Flu {ibid. XII Bd. 1908) and Berliner {ibid. XV Bd. 1909) describe the occurrence of individuals with a similar defect in Crithidia melophagia and 1 Ehrlich has found tliat Trypanosomes which have become resistant to orthoquinoid substances are also resistant to arsenic compounds — a very curious phenomenon. He also found, conversely, that races resistant to arsenic are resistant to the orthoquinoid diphenyl- methane derivatives. 2 Not an orthoquinoid substance, and usually without action upon the kinetonucleus. ^ The relapse race may have been formed by selection — a chance individual with no kinetonucleus having been more resistant to the drug than the norrnal forms, and having survived the injection and given rise to the new race. •212 Mutation in Micro-Organisms Herpetomonas jaculum respectively. It is unfortunate that the origin of these forms is as yet quite unknown \ Probably they were merely degenerate individuals. B. Physiological Mutations. It has now been known for some years — largely through the work of Ehrlich aud his collaborators — that drugs and antibodies may modify profoundly the physiological properties of Trypanosomes. As early as 1907, Ehrlich showed that treatment of Trypanosome-infected animals with atoxyl- might cause — under certain conditions — the Trypanosomes to acquire an immunity to the drug. By subjecting the Trypanosomes to the action of minute but increasing quantities of atoxyl or other drugs, Ehrlich has succeeded in obtaining strains of the parasites which are highly resistant' to these poisons. In 1909 he stated that he had pro- duced an arsenic-resistant strain of T. hriicei, which had, in the course of three years, undergone passages through some four hundred untreated animals — without any loss of resistance to arsenic. Many similar ob- servations have since been recorded, so that it may now be stated as a fact that physiologically modified races of Trypanosomes can be made by artificial means from the races which occur normally in nature. Mesuil and Biimont (1908) also succeeded in obtaining a race of Trypanosomes resistant to ato.xyl. But they pointed out that the re- sistance was only manifested " in a given organism " (i.e. host). More definite in this respect, however, were the statements of Breinl and Nierenstein (1908)^ From inoculation experiments, they concluded that a Trypanosome's resistance to the drug is manifested in that . 1 It should be remembered that Trypanosomes which have grown in artificial culture media frequently display morphological peculiarities — as regards size, shape, relative position of nuclei, etc. These modifications are, however, transitory : they do not persist after the organisms have been reinoculated into the animals which are their normal hosts. - Atoxyl is sodium arsanilate— the Na salt of ^j-aminophenyl-arsenic acid (Ehrlich and Bertheim). ^ A Trypauosome which tolerates the action of a drug is generally said to be " fast " to the drug in question, e.g. a Trypanosome which has been rendered tolerant to atoxyl or other organic arsenicals is spoken of as "arsenic- fast." The word "fast" has, however, an older and very different usage in bacteriology. For instance, tubercle Bacilli — and certain others— are called "acid-fast." This does not mean that the living organisms tolerate, or are resistant to, acids: it means that lUad organisms wlien stained with carbol-fuchsin are stained " fast " (in the dyer's sense) against mineral acids. I therefore prefer to use "resistant" rather than "fast" when discussing the phenomena of living Trypanosomes. ■* These workers, it may be noted, give an incorrect account of the results of Mesnil and Brimont. C. DOBELL 213 species of host animal alone in which it was acquired. Fur example, they found that T. brucei in donkeys became resistant to atoxyl after injections of the drug. Transplanted into rats, however, it rapidly lost its resistance and became susceptible again. Races of Trypanosomes with a changed virulence, produced by passages through a different host, have several times been recorded. Fellmer (1907), for example, stated that the virulence of T. brucei was diminished by passage through the hedgehog. The structure of the parasites was also stated to be modified by a sojourn of the race in this animal. Fellmer's experiments were repeated by Gonder and Sieber (1909), who used both T. brucei and T. eqidpej-dum. They com- pletely failed, however, to produce any change in either the virulence or the structure of these Trypanosomes in this way. Wendelstadt (1909) and Wendelstadt and Fellmer (1909, 1910) also announced that the passage of T. brucei and T. lewisi through cold- blooded vertebrates — to which reference has already been made — greatly modified their virulence. They found, for example, that T. lewisi when passed through the grass snake becomes modified into a race which is pathogenic for rats — in which the infection is normally harmless. Inoculation of Trypanosomes from the snake back into the rat kills the latter. Twenty-four passages with a similar result were thus made. Laveran and Fettit (1909) repeated these experiments. They injected both T. lewisi and T. evansi from rats into snakes, and then back into clean rats. But they failed entirely to produce any change in the virulence of the Trypanosomes. They state, moreover, that the blood of the snake is very toxic to rats — which may account for the results of Wendelstadt and Fellmer. It seems, therefore, that these experiments in which ciianges of virulence are said to have been produced in Trypanosomes should be regarded with considerable scepticism for the presents Levaditi and Mutermilch (1909) found that they could produce races of T. brucei which were resistant to certain antibodies. Later, Levaditi, in collaboration with Twort (1911), has shcnvn that a race of T. brucei can be made which is resistant to the toxin produced by Bacillus subtilis — a substance which is usually very toxic to T. brucei. If a normal race of this Trypauosonie (from the blood of the mouse) is subjected in vitro — even for only a few minutes — to the action of ' It should be recalled, however, that the Werbitzki races of Trypanosomes have undergone a diminution in their virulence — a fact which appears to be established (Laverau and Eoudsky). 214 Mutation in Micro- Orr/anisms the toxin, it is found, after reinocalation into a mouse, to have acquired a marked resistance to it. A subtilis-toxin-refiisto-nt strain of T. bnwei has been thus produced which remains as such during subsequent animal passages — that is, the acquired resistance of the Trypanosomes is trans- mitted hereditarily. Most important and extensive work in this direction has been recently published by Gonder (1911), whose results may now be con- sidered in some detail. The work, was carried out in Ehrlich's laboratory, where it was begun by Werbitzki. In his experiments, Gonder used two strains of T. lewisi. These were, first, a strain from wild rats, grown in tame laboratory animals and susceptible to arsenic. An injection of 01 gm. of arsenophenyl- glycin per kilogram body-weight of rat sufficed to kill all the Trypano- somes in its blood. Tliis strain, after numerous passages through normal rats, always remained susceptible to arsenic. The second strain was one which had been made arsenic-resistant'. It was made by accustoming the Trypanosomes to minute but gradually increasing doses of arseuophenylglycin. Finally — after two years — a strain of T. lewisi was obtained which was resistant to the drug to such an extent that it was unafifected by injections of 0"2 gm. per kilo. Passage of this strain through untreated rats showed that the arsenic -resistance had become fixed, and was transmitted hereditarily. At the twentieth passage, the resistance was unchanged". As regards structure, and behaviour in other ways, the Trypanosomes were found to be indis- tinguishable from the normal race. Gonder found that both the non-resistant and the resistant race could be transmitted from rat to rat by the rat louse, Haematopinus spinulosus — which is supposed by some workers to be the usual inter- mediate host of T. lewisi in nature. The incubation period in the louse was found to be 15 — 17 days in the case of the normal race (3 rats); 25 — 30 days (6 rats) in the case of the arsenic-resistant race. The two races of Trypanosomes were then tested as regards their resistance to arsenic. And the results showed that all the Trypanosomes — whether they had previously been resistant or not — were non-resistant to arsenic after development in the body of the louse. ' Arsenic-resistant strains of Trypanosomes can be rapidly prodaced by treatment with a number of different organic arsenic compounds, and also by the action of dyes of an ortlioquinoid type (Ehrlich, 1911). - Similar arsenic-resistant races of other Trypanosomes had, of course, been previously produced by Ehrlich and others. C. DOBELL 215 In two cases, where mechanical transmission by the louse was believed to have occurred — that is, where no development of the Trypanosomes in the louse intervened — it was found that the transmitted Trypanosomes had retained their power of resisting arsenic. The incubation period in the louse in these cases was only 5 days. By daily injecting emulsions made from the bodies of lice — in which Trypanosomes were developing — into uninfected rats, Gonder was able to determine how long the arsenic-resistance of the Trypanosomes persists. He found that it persists for 12 days in the body of the louse. After this period, the Trypanosomes lose their resistance to arsenic, and become normal. Cultures of normal and arsenic-resistant races of T. lewisi were made in artificial media'. Both races behaved exactly alike. The non-resistant races, when reinoculated into rats, were still non-re- sistant: the arsenic-resistant races remained arsenic-resistant. Both races underwent similar structural changes in the cultures — being gradually converted into Crithidia-Vike forms in the course of some 3 months. These forms, when injected back into rats, assumed the normal Trypanosome form once more — the incubation period being 3 — 11 days. Multiplication occurred in the artificial cultures. Ehrlich (1911) and Gonder (1911) have interpreted the foregoing facts in the following way. They suppose that the development which T. leiuisi xmdergoes in the louse constitutes a sexual cycle in the life- history of this species. They suppose that the resistance to arsenic, which the Trypanosomes have been made to acquire, persists only so long as the asexual cycle endures — that is, during the period when the Trypanosomes are in the blood of the rat, or in artificial culture media. When the sexual cycle takes place in the body of the louse, the acquired resistance of the race is lost, and the individuals revert to their original non-resistant condition. The "acquired character" is thus "inherited" in asexual reproduction only-. This extremely interesting and suggestive idea cannot be regarded at present as anything more than a hypothesis. For in the first place. ' T. leioisi was first successfully cultivated in an artificial medium by Novy and MacNeal, in 1903. Since then, many other workers have succeeded in cultivating a number of other species. ° Far-reaching conclusions regarding " the inheritance of acquired characters " can be di'awn from these experiments only by those who are content with words and unable or unwilling to analyse the facts. 216 Miitation in Mlcro-Organisms it lias not been proved that the louse is the normal intermediate host of T. lewisi. There is much evidence to show that it is the flea, and not the louse, which is the normal carrier of the Trypanosome from rat to rat: though the louse may occasionally be the means of infection. Secondly, it has never yet been proved that the development which the Trypanosomes undergo in the gut of the louse is a sexual development. A sexual cycle in the louse was first described by Prowazek, and has since been alleged to occur by Baldrey, Rodeuwaldt, and others, whose results Gonder says he can confirm "almost entirely." To prove the existence of a sexual cycle in the louse, however, something more than the arbitrary seriation of certain stained specimens is requisite. Until the publication of more convincing evidence — derived from a study of the living organisms, and from careful cytological research — it is not justifiable to conclude that conjugation of the Trypanosomes occurs in the body of the louse. It is, moreover, obvious that Gonder's own results cannot be held to prove that conjugation occurs in the louse: his interpretation is based on the supposition that conjugation does occur. And there is really no reason why the development — which the Trypanosomes appear undoubtedly to undergo — in the louse, should be regarded as necessarily of a sexual nature. Since it has been found (Mesnil and Brimont [1908], Breinl and Nierenstein [1908]) that the resistance of a race of Trypanosomes to arsenic is manifested only so long as the race remains in a given host, it is not impossible that Gonder's results are explicable on the same principle. T. leivisi niay remain arsenic-resistant so long as it con- tinues in the blood of the rat, or in an artificial medium : but a change of host {i.e. from rat to louse) may abolish the resistance — just as T. brucei, arsenic-resistant in donkeys, becomes non-resistant when trans- planted into rats. (Of. p. 213.) If one substance can bring about arsenic-resistance, it is at least conceivable that another substance can remove it. And it is possible that the body of the louse may furnish such a substance. At all events, there is no need to assume the existence of sexual phenomena to account for the results of the experiments. Ehrlich and his followers regard resistance to di'ugs or sera as a direct consequence of the action of the substances in question upon tlie living protoplasm. That is to say, they suppose that when a Trypanosome is treated with a minute quantity of arsenic, its proto- plasm becomes changed in such a way as to make it resist the drug when applied subsequently. New races of Trypanosomes are thus C. DOBBLL 217 supposed to be directly produced by a modification of the individuals of the old race'. Erhlich's views in this respect are not shared by some other workers. Levaditi, with Mutermilch (1909) and Twort (1911), interpreted his own results as due to selection b}' the poison employed. The toxin of B. suhtilis was found to kill or affect many Trypanosonies, when observed in vitro. And it was concluded that " certain races of Trypanosonies, considered as homogeneous, are only, in reality, a mixture of a large number of individuals endowed with unequal susceptibility towards a given trypanocidal poison." (Levaditi and Twort [1911].) In other words, resistant pure lines may be formed from a mixed population by the selective action of a poison — only those naturally most tolerant Trypanosonies being able to survive, and to perpetuate the race. It therefore seems uncertain how resistant races of Trypanosomes arise. It is possible, however, that both a direct action of the drug and an indirect selection by it play a part in their formation. In conclusion the more important results noticed in the foregoing pages may be very briefly summarized. I will limit myself to only those conclusions which appear to me to be justified at the present moment. (A) It has been stated that the passage of certain Trypanosomes, which normally occur in mammals, through cold-blooded vertebrates and certain invertebrates, causes them to undergo certain structural changes which persist during subsequent divisions (Wendelstadt and Fellmer). This work has not yet been confirmed. It has further been stated (Werbitzki) and confirmed (Laveran and Roudsky, Kudicke) that certain dyes can destroy a definite organ (kinetonucleus) in a Trypanosome, without killing or injuring it or impairing its power of propagation. Thus new races of Trypanosomes may be produced which completely lack this organ. It has, moreover, been rendered highly probable that the dyes which have this power possess a certain chemical structure (ortboquinoid substances of Ehrlich): 1 According to Ehrlich (1911), resistant races of Trypanosomes are of two quite different sorts: (1) Serum-resistant, i.e. resistant to specific antibodies; (2) Chemo-resistant, i.e. resistant to various chemicals. Such races are supposed to arise in different ways. In the terms of Ehrlich's theory, a serum-resistant race is formed by the serum causing a certain receptor (uutriceptor) to disappear, when it is replaced by an altogether new kind of receptor. A chemo-resistant race, on the other hand, is produced, not by the replace- ment of one receptor by another, but by the diminution (" Herabminderung") of a certain chemical function. 218 Mutation in Micro-Organisms and that the dyes have a specific action upon the kinetonucleus — but upon no other organ in tlie Trypanosome — and bring about its destruction by autoxidation (Laveran and Roudskv). New races of Trypanosomes are thus produced by modifying the individuals of the old — not by selection. (B) Races of Trypanosomes without kinetonuclei possess a hnveied virulence (Werbitzki, Laveran and Roudsky). By the action of various drugs and antibodies, races of Trypanosomes may be obtained which are resistant to these substances (Ehrlicli, Mesnil and Brimont, Breinl and Nierenstein, Levaditi and Twort, etc.). These races subsequently breed true — though it may be a necessary condition of this that they be kept in the same sort of host as that in which they originally acquired their resistance. Races of Trypanosomes with a changed virulence are said to be pro- duced by passage through certain animals (Wendelstadt and Fellmer) : but this lias been denied (Gonder and Sieber, Laveran and Pettit). By treating T. leiuisi with arsenophenylglycin, a race may be obtained which is resistant to this drug. This race breeds true — retaining its resistance during numerous passages through untreated rats. Resistant and non-resistant races remain unchanged, as regards this character, when grown in artificial cultures. When the resistant race undergoes a development in the louse — the exact nature of which is not determined, though it is possibly sexual — resistance is gradually lost, and the race returns to the original non-resistant condition (Gonder). It has not been definitely determined whether resistance is brought about by the direct action of the poison on the living Trypanosome (Elirlich, etc.), or whether it is the result of selection (Levaditi, etc.). That some of the observations noticed in the course of this review are of great interest, I think nobody would deny. And that they may lead to a better comprehension of the phenomenon of mutation in general is at least possible. In his Dresden address in 1911 Ehrlich said: "...Aber, meine Herren, in der Natur ist nichts spontan, alles hat seine Ursache, und wenn es sich um biologische Fragen handelt, meistens eine chemische Ursache. ...So glaube ich, dass gerade diese Studien an Parasiten, an kiinstlich herbeigefiihrten Mutationen durch bestimmte biologische Eingriffe, deren Mechanismus genau erklarbar ist, uns auch ein belles Licht iiber die so dunklen Fragen der Mutation iiberhaupt bringen werden." (Ehrlich [1911], p. 95.) Though all may C. DOBBLL 219 not take so confident and hopeful a view, this expression of opinion is noteworthy, and indicates the vast possibilities which the futui-e still holds for one branch of biological research. LITERATURE. 1908. Breinl, a. and Nibrenstein, M. "Weitere Beobachtungen iiber Atoxyl- festigkeit der Trypanosomcn." Deutsch. med. Wocheiischr. No. 27. 1907. Ehrlich, p. "Cliemotherapeutische Trypanosoiuenstudien." Berliner klin. Wochenschr. XLIV. p. 233, etc. 1909. . " Ueber die ueuesten Ergebiiisse auf dem Gebiete der Trypano.somen- forscbung." Arch. Schijfs- u. Trupenhyg. Beih. VI. p. 91. 1911. . "Ueber Chomotherapie." Ber. iib. 5 Tagung d. Freien Vereinig. f. Mikrobiol. i. d. lutertiat. Hygiene- Austellung Dre.sdeii, in : C. B. Bakt. Beil. z. Abt. i. Bd. l. (Ref.), p. 94. 1907. Fellmer, T. " Veranderuiigeu an Nagaiiatrypanosomen durt-h Igelpassage." C. B. Bakt. I. Abt. (Orig.), Bd. xlv. p. 512. 1911. GoNDER, R. " Uutersuchuiigen Uber arzneifeste Mikroorganismen. I. Tri/- panosoma lewisi.'" C. B. Bakt. I. Abt. (Orig.), Bd. LXI. p. 102. 1909. and Sieber, H. " Experimentelle Untersuchungen liber Trypano- somen." C. B. Bakt. i. Abt. (Orig.), Bd. xlix. p. 321. 1911. KuDlCKE, R. " Die Wirkung orthochinoider Substanzen auf Rattentiypano- somen." C. B. Bakt. i. Abt. (Orig.), Bd. lix. p. 182. 1911a. . "Beitriige zur Biologie der Trypanosomen." C. B. Bakt. i. Abt. (Orig.), Bd. LXI. p. 113. 1911. Laveran, A. " Contribution ii I'etude du Tri/panosoma brucei sans bldph- aroplaste de Werbitzki." Btdl. iSoc. Path. exot. No. 4, p. 233. 1911 A. . "All sujet de Trypanosoma brucei sans blepharoplaste de Werbitzki." Bull. Soc. Path. exot. No. 5, p. 273. 1909. and Pettit, A. " La virulence des trypanosomes des Mammiferes peut-elle etre moditiee apres passage par des Vertebres k sang froid ? •' G. a. Acad. Sci. Paris, Tom. CXLIX. p. 329. 1911. and Roddsky, D. "Au sujet de Taction de I'oxazine (chlorure de triaminophenazoxonium) sur les Trypanosomes." C R. Acad. Sci. Paris, Tom. CLiii. p. 226. 1911a. . "Au sujet de Faction de I'oxazine (chlorure de triaminopWn- azoxonium) et de I'akridine (diphcnylmethane) sur les Trypanosomes." C. R. Acad. Sci. Paris, Tom. cliii. p. 916. 1909. Levaditi, C. and Mutermilch, S. " Le mecanisme de la creation des varietes de Trypanosomes resistants aux anticorps." C. R. Soc. Biol. Tom. Lxvii. p. 49. •220 Mutation in Micro- Organisms 1911. Levaditi, C. and Twort, C. " Sur la trypanotosin dii Bacillus suhtilU, etc." A series of seven papers, in C. R. Soc. Biol. Vol. Lxx. pp. 645, 753, 799, 927, 962, 1024, and Vol. Lxxi. p. 127. 1908. Mesnil, F. and Brimont, E. " Sur les proprietes des races de trypanosomes rtsistantes aux mt'dicaiuents." Ann. Inst. Pasteur, Tom. xxil. p. 856. 1909. Wendelstadt, H. " Ueber Form- und Virulenziinderungen von Trypano- sornen durch KaltblUterpassage." Med. KHn. Nr. 16, p. 608. 1909. and Fellmee, T. " Einwirkuug von Kaltbliitcrpassagen auf Nagana- und Lewisi-Trypanosomen." Zeitschr. f. I'lnnnmitatsforsch. Bd. III. p. 422. 1910. . " Einwirkung von Kaltbliiterpassagen auf Nagana- luid Lewisi- Trypanosomen. II. Mitteilung." Zeitschr. f. Immunitatsforsch. Bd. v. p. 337. 1910. Werbitzki, F. W. " Ueber blepharoblastlose Trypanosomen." C. B. Bakt. I. Abt. (Orig.), Bd. Liii. p. 303. INHERITANCE OF COAT-COLOUR IN RABBITS. By R. C. PUNNETT, M.A., F.R.S. CONTENTS. PAGE Introduction . 221 General scheme of the experiments 222 The Fi generation 223 The F2 generation 223 Agouti from black x black 225 The Hypothesis 227 The Fs generation ........ 229 The synthesis of agouti bearing blacks .... 233 The test of the coupling between D and E . . . 234 The chocolate series ........ 235 The Himalayan pattern 236 Introduction. When the following experiments were started ia 1907 we were already familiar, through the work of Castle (1) and Hurst (.5). with certain phenomena in the inheritance of coat-colour and pattern among rabbits. These investigators had shewn that the wild grey, or agouti, is dominant to black, and that these tw(j full colours are respectively dominant to the two dilute forms, yellow and tortoise (= the " sooty- yellow " of Castle). Moreover with regard to pattern Hurst had published a brief statement (6) to the effect that Dutch marking is recessive to self-colour, the heterozygote being variably marked, and that the Himalayan pattern is recessive to the self-coloured form. Castle also(l) had given an account of a few experiments with the Himalayan in which this form was shewn to be dominant to the pure albino. More recently (1909) Castle has published a general account (3) of the colour varieties in the rabbit that have so far been analysed. With that account m}' own work is iu general agreement, and in so far as is possible I have adopted his system of nomenclature for the various factors concerned'. ' Of the four colour varieties agouti, yellow, black, and tortoise, the two former are regarded as containing the agouti factor A which is absent from the black and the tortoise. The agouti and black again differ from the yellow and the tortoise in containing a factor E for the extension of the pigment. Melanic pigment occur.s also in the tortoise and the yellow but in much smaller amount and is chiefly localised in the nose, ears, tail, and feet. Journ. of Gen. 11 16 ooo Coat-Colonr in Rabbits General Scheme of the Experiments. My own experiments were started with the idea of investigating more fully the genetics of the Dutch and Himalayan patterns, but they had not proceeded far when it became evident that certain phenomena in connection with the inheritance of colour were unlike any hitherto met with, and promised results of unusual interest. It is with these colour phenomena, that the present paper is concerned. At the same time I can confirm Hurst's statement as to the recessive nature of the Himalayan pattern, though with regard to the nature of the Dutch marking and its relation to the self-coloured form I am inclined to think that the matter is more complicated than his account appears to imply. Experiments on the inheritance of coat-pattei-n are still in progress and I hope to publish them when more complete. Pattern and colour appear however to be t[uite independent of one another and in the present paper the results will be treated solely from the standpoint of colour. The subjoined scheme provides a general view of the experiments. The qualitative result of the various matings is alone indicated. The quantitative results will be found in the various tables to which reference is given. Fi F2\ fA Tort. X Him. Him. x Yel. Yel. x Him. [?7] [> TABLE VIII. No. of Female Male E 31 (heterozygous yellow) Male 74 (pure tortoise) Agouti Black Agouti Black , B 76 — — 2 6 B 151 — — 2 4 B 191 — 5 1 G C144 — — 2 10 D 20 4 4 — — F., Agouti-black ? '{ D 21 IJ133 3 2 4 — — Z)145 2 G — — K156 — ^ 3 3 Din — — 1 14 D237 — — 2 4 \E 35 — — 2 4 Totals 9 21 15 51 Expectation 11-35 18-75 w-s 49-5 R. C. PUNNETT 233 Eight of the agouti-blaek does were also crossed with a pure tortoise buck (j/* 74), and the uumbers obtained, 51 black and 15 agouti, tally closely with the expected 3 : 1 ratio. It may therefore be fairly claimed that the constitution of the F-, generation from ^ 28 as tested by further breeding from them is in accordance with the hypothesis framed above. The Synthesis of agouti-bearing blacks. So far the evidence that a rabbit, visibly pure black, can carry the agouti factor rests entirely upon a single individual — the Fi ^ 28. But if our hypothesis is correct, there should be no difficulty in synthe- sising the agouti-bearing black from the material to hand, and as a matter of fact this has actually been done within the past year. Reference to Fig. 3 (p. 232) shews that of the five blacks resulting from the mating of agouti-black with yellow three carry the factor A, two being heterozygous and one homozygous for that factor. Neither of the two remaining blacks carries A. The simplest way to find these blacks would be to test them by crossing with a pure black of the constitution ddEEaa. As however I had not such an animal ready to hand, I used for testing purposes a chocolate J" which had previously been shewn to be homozygous for E, but to contain neither D nor A^ In this way 13 black does ex agouti-black x yellow have been tested, with the result that three proved to be homozygous for A, four proved to be heterozygous, while in the remaining six A was absent. The details are given in Table IX. .' TABLE IX. X Male E 31 X Chocolate male (ddEEaa) Blk. (heterozygous yellow = ddeeAa) No. of Female Blk. Ag.-Blk. Ag. (ffim.) Ag. YeUow Tort. (Him. F 63 — 4 3 (3) 2 — 2 — (1) DdEeAA F 67 — 4 5 (i) 1 — 2 — — [ F\iS, — (1?) 5 — 2 — 4 — — , F 22 6 1 — 4 — 1 1 — F 62 3 1 (4) 1 — 1 1 (1) DdBeAa ^ g^_ 1 2 1 (1) 3 — 2 2 (1) F 69 2 1 — — 2 — 4 3 (1) F 9 10 — — — F 10 11 DdEeaa j,, ^^ 9 — "^ \ FQO 5 ddEeaa ^ g^ 7 — — (2) F 64 5 — — — ' For a further account of this animal see later, p. 235. 234 Coaf-Colour hi Rabbits At the same time five black {/'J' bred similarly to the above black $ J were also tested. Of these one turned' out to be homozygous for A, two turned out to be heterozygous, while the reniaiuiug two did not carr}' A. In all therefore 18 blacks from the mating of agouti-black X yellow were tested for tlie presence of A, and as the subjoined list shews the proportion of those houiozygou.s for A, heterozygous for A, or homozygous for its absence tallies closely with expectation: AA Aa aa Proportion found by testing 4 6 8 Proportion expected 3-6 7-^ 7-2 The test of the couplinr/ between D and E. The possession of a number of agouti- bearing blacks renders possible the carrying out of a critical test to decide whether the suggested coupling between D and E occurs. On tliis hypothesis the gametes produced bj' the agouti-bearing black are DEA, DEa, deA, dea if it is heterozygous for A, and DEA, deA if it is homozygous. Such animals when mated with yellows or tortoises should be able to give yellow offspring but no agouti. And as one of the parents in such a mating lacks the factor E, no agouti-blacks should appear from such matings. In Table IX are shewn the results of crossing the agouti- bearing black % $ with a heterozygous yellow j/' {E 31). Hitherto from such matings have come 15 blacks, 16 yellows, and 7 tortoises, but no agoutis or agouti-blacks. A few families have also been raised from agouti-bearing black (^^^ and tortoise % $, viz. : Black Agouti Yellow Tortoise :p. ZooL, 1911. (8) Woods, F. A. " Mendel's Law and some records in Rabbit Breeding " Biometrika, 1903. JOURNAL OF GENETICS, VOL. II. NO. 3 Fig. 1. Agouti-black (heterozygous for black). Fig. 2. Agouti-black (homozygous for black). PLATE XII 'r:. k Si -i'^^ 1 4^ Fig. 3. Deep cinnamon-agouti. Fifj. 4. Cliocolate. JOURNAL OF GENETICS, VOL. II. NO. 3 V ,,^ \ ¥ ,1 *> ■^ Fig. 1. Orange. Fi!-. 2. Yellow. PLATE XIII H ... '■ ' I Fig. 3. Cinnaraou-agouti. Fig. 4. Tortoise. JOURNAL OF GENETICS, VOL. M, NO. 3 PLATE XIV * V Fig. 1. Fig. 2. ON THE INHERITANCE OF CERTAIN CHARACTERS IN THE COMMON GROUNDSEL — SENECIO VULGARIS, LINN.—A.^D ITS SEGREGATES. By a. H. trow, D.Sc, F.L.S. Introduction. The common groundsel is a plant of world-wide distribution and one might reasonably expect that its various forms would be well known to botanists. In Koch's Synopsis, Ed. ill. 1902, two varieties only are recognised, sordidus and radiatus, and the descriptions are unfortunately too brief and too vague to be of much value. Rouy, in the Flore de France, Vol. viii, p. 343, adds two more — crassifolius and Motelayi, which are also badly defined and inadequately investigated. The majority of botanists recognise two forms only : (a) the type form S. vulgaris, Linn, which is non-radiate, and (6) a variety of this with ligulate ray florets, S. vulgaris, Linn., var. radiatus, Koch. It is noteworthy that although the Compositae constitute about one-tenth of the phanerogamic flora of the world, they have received comparatively little attention so far from those who are engaged in experiments on plant breeding. Moreover, numerous plant hybrids are rec(jgnised in every modern flora, but comparatively few of them have hitiierto been tested by the methods of genetics. Certain plant genera, such as Hieracium, Rosa and Rnbus have been studied intensively to such an extent that old well-known species \\ke Rubus fruticosus and Rosa canina have been split up into numerous smaller units recognisable with certainty only after much painstaking study, yet there has been practically little effort, except in Hieracium, to trace by experimental means the genetic relationships of such forms. Indeed the stiidy of "critical" species is carried on still almost entirely 17—2 240 Inheritance in the Groundsel by morphological methods alone. Such methods, valuable and even indispensable though they may be, are nevertheless inadequate for the complete solution of such intricate problems as need investigation in these cases. Few weeds, moreover, have been as yet studied by experimental methods ; the classical work in genetics has been done on species and varieties of plants long cultivated in gardens — peas, sweet peas, snap- dragons, stocks, etc. Such considerations as these induced me, six years ago, to undertake a genetic study of the common groundsel and its segregates. Although it soon became obvious that I should have to register annually two to three thousand plants, and sacrifice the greater part of each long vacation, the results were of sufficient interest to cause me to extend the work year by year. Although the investigation, as a whole, is still very incomplete, it seems desirable that some of the chief results of the last six years' work should now be placed on record. Origin of the Experimental Material. Methods. The Radiate Character RR. In the year 1891 or 1S92 I observed and examined hundreds of specimens of a groundsel growing in abundance near Cardiff and Penarth, which was chiefly remarkable for its conspicuous capitula, each of which bore from eight to 13 large ray florets. In January, 1894, Dr C. T. Vachell called attention to this plant at a meeting (if the Biological Section of the Cardiff Naturalists' Society and specimens were submitted to W. B. Hemsley, who reported on them as follows; — "I cannot make anything of this but vulgaris b. radiatvs." I had already expressed the .same view, with certain reservations ; based on the fact, that although these plants were clearly radiate gmundsels, they did not agree well with the description and figure of the Channel Islands plant in Sowerby's Botani/. The same groundsel occuis in abundance near Swindon, Cork, and Northwich, where, as at Cardiff, it is frequently accompanied by 8. squalidus. It has also been sent to me from the Cambridge Botanic Gardens by Mr I. B. Pole-Evans and Prof Yapp. It has spread widely in the counties of Glamorgan and Monmouth in recent years, and specimens have been received recently through Dr Moss from North- wich, Cheshire, and Freshfield, Lancashire. The only other locality recorded for it in Great Britain appeal's to be Bigbury, S. Devon. It A. H. Trow 241 certainly flourishes in localities where S. squalidus does not occur, and as we shall see, these two species appear to have no necessary association with each other. A capitulum of this radiate groundsel, from one of 49 plants of the pure strain cultivated in 1912 (7th Generation) which I have named erectus, radiatus, is represented in PL XVI, fig. 8. This strain occurred originally as a weed in my own garden along with a non-radiate form, indistinguishable from it until the opening of the flowers, when of course the difference is very obvious. The non-radiate type may be styled e^-ectus. Its capitulum is shewn in PI. XVII, fig. 14. Either form may thus be regarded as a true variety of the other, using the term variety in the sense suggested by De Vries. In the year 1904, I noticed a single plant whose capitula differed from those of the two preceding. Each capitulum had eight to 13 ligulate ray florets, but the ligules were only one-half the usual length and were conspicuously three-toothed at the apex (PL XVI, fig. 5 and text-figure 29, p. 274). Perhaps influenced by the prevalent view that groundsels are autogamous plants (self-pollinated), this was regarded as a mutation, and the supj)osed mutant was allowed to seed freely, but no seeds were collected. In 190.5, as a result of the natural sowing, a small crop of groundsels appeared in which the three types were present, and I resolved to start a set of pedigree cultures to determine their relationships to each other. It will be convenient to denote the three types as follows: — ■(!) the radiate plants with the ray character fully developed by RR (PL XVI, fig. 4), (2) the non-radiate plants by NN (PL XVI, fig. 6), and (3) the intermediate plants with the ray character partly developed by NR (PL XVI, fig. o). The figures apply equally well to the erectus and midticaulis types. In all the experiments methods were employed to secure the absence of all foreign seed from the cultures. The soil and seed-pans were sterilized by submission to one hour's steaming. So effective were these precautions that from 1905 to 1911 I have only found two invading seedlings in the seed-pans; one of a Trifolium, the other of Foa annua, while the controls were invariably sterile. Preliminary experiments, Nos. 1, 2, 3, 4 and 5. The first experi- ments were more or less tentative and were made to test the inheritance of the full ray-character in RR plants. Exp. 1. A single head of seeds (really fruits) was collected from a plant growing as a weed in the garden in September, 1905, and the seeds were sown at once. Thirty- 242 Inheritance in the Groundsel six seedlings were raised, eight of these ultimately flowered, and all proved to be RR. Exp. 2. One of these eight plants was isolated in the greenhouse, and from its seeds one hundred and nineteen seedlings were raised in the following year. Of these one hundred and sixteen flowered, and all were RR. Exp. 3. Another experiment carried out under somewhat different conditions gave the following result. Five plants flowered in 1905, all RR. Exps. 4 and 5. From two of these five plants seeds were obtained (a) after isolating in the greenhouse, {h) after selfing in the open air. These seeds produced respectively 74 and 13 plants, all RR. Altogether 216 plants were raised in two generations, and all were RR, breeding perfectly true to the parent type. Exps. 6, 7 and 8. Further experiments were set up to test the inheritance in all three types under natural conditions — cross polli- nation by natural agents being possible. Thi-ee plants growing close together, but not in contact, in the open garden, of types NN, RR and NR were marked down for seed-saving on September 16th, 1905. Seed was collected as follows : — From NN. From Oct. IGth to Nov. 17th. 33 Heads on 17 separate days. From ER. From Sept. Kith to Nov. 17th. 43 Heads ou 20 separate days. From NR. From Sept. 20th to Nov. 17th. 30 Heads on 14 separate days. The results are summarised in TABLE I. Seeds Date of Sowing No. ot plants raised No. of plants flowered Distribution of Ty]ies Exp. NN HE NR Exp. 6 NN 11.4.06 463 439 436 0 3 Exp. 7 ER 3.4.06 660 617 0 616 1 Exp. 8 NR 3.4.06 491 449 109 114 226 • The interpretation of these three experiments is clear: NN and RR are homozygotic forms so far as concerns the ray character, and NR is the corresponding heterozygotic form. In addition to this main con- clusion it may be noted that cross-fertilization, with the production of natural hybrids, takes place in both ways, N^ x R and R x N, and may produce an error of about 1 °/^ unless measures are taken to prevent it. This error is so small that it might be neglected, if constant. Sub- sequent experiments, however, shew that the error due to the absence of selfing may reach 10 °/^ or more. Such free natural crossing as is represented by a 10°/^ error is due to (1) vicinism in its various forms, (2) msits hy honey-bees — in a bad honey season, the groundsels, radiate and non-radiate, are freely worked by these insects, (3) Aphis, the A. H. Trow 243 wino-ed form of which doubtless carries pollen freely, and (4) various other insects. Selfing is therefore necessary and has been carried out in various ways; viz. (1) under a framework covered with muslin, (2) inside muslin bags, the mouths of which have been carefully closed with cotton wool — the most effective open-air method, (3) by isolation in the greenhouse — the most effective method of all, and perhaps abso- lutely safe when muslin bags are used as well. Before making crosses, it is of course necessary to self both parents— a precaution neglected in some of the earlier experiments. Constant handling of groundsels soon trained the eye to the per- ception.of comparatively slight differences of form, and at an early stage in the investigation (1904) distinct strains were collected and separated which can be regarded provisionally as elementary species. Three of these, named lyraecox, latifoliits and multicatdis, were non-radiate, and were soon subjected to the test of experimental culture. Praecox was first noted in 1904, growing in the Cathays Park, Canliff, in a colony of about a hundred plants, associated with an erectes-like and much larger form. In 1905 a single head of seeds was collected, and the type has since then been cultivated and main- tained as a pure strain for six generations (1906 to 1911). The plants are early and dwarf, with dark-green slightly cut leaves and reddish glabrous stems with long internodes and few nodes. (PI. XV, fig. 1 and PL XVII, fig. 13.) Latifoliiis is of garden origin and has been maintained pure in type for five generations. It has broad incurved leaves, glabrous and shining above, and is a tall erect plant like erectus. Multicaulis was first observed near Ba,rry, and has been cultivated for five generations. It is rather late, generally produces many strong branches from the axils of the basal rosette of leaves, has glabrous green stems, dark-green leaves, yellowish-cream coloured flowers, and large capitula. (PI. XVII, fig. 12.) Genevensis is the name given to a non-radiate type which occurs abundantly, apparently unmixed with other forms, in the vineyards about Montreux, and which resembles praecox. It has small capitula. (PI. XVII, figs. 15 and 16.) ,,: ," ' . - \ . ,•• ■. : •. The full pedigrees of these types and a more detailed consideration of their characters are not required for our immediate purposes. But it seemed to me of some importance to test whether the rayed character RR was transferable to these lour non-radiate types.^ If one 244 Inheritance in the Groundsel could produce the hybrid in each case and from its progeny select the corresponding radiate form, one would be able to demonstrate two facts of importance: (1) the general transmissibility of the RR character, and (2) the realitj' and permanence of the characters which serve to define the four types. This transference has been successfully made and the new types thus produced have been maintained as pure cultures for various periods. a. Praccox, radiatus was produced in 1908 and has been kept pure for 3 i,'enerations. (PI. XVI, fig. 7.) b. Latifolius, radiutus ,, 1908 „ ,, 3 ,, c. Multicaulis, radiatus „ 1909 ,, ,, 2 „ (PI. XVI, fig. 4.) d. Genevensis, radiatus ,, 1911. (PI. XVI, fig. 9.) Methods of crossing adopted to secure the F^ generation in each case. It is of course possible to cross radiate groundsels by removing the disc florets while they are still young and crossing the ray florets with foreign pollen. Seeds have been actually obtained from 8. viscosus and fi-om S. squaUdus when endeavouring to obtain hybrids in this way, but the plants raised from them were in each case identical in character with the mother plants. There are two possible inter- pretations of such results : — either (1) the ray florets are apogamous and are thus independent of fertilization, or (2) pollen of the same type as that of the mother plant accidentally reached the stigmas. It is quite likely that the ray florets of one of these species are apogamous. Though then it may be possible to cross the individual flowers of the common groundsel, it is not practicable in the open air, and in the green- house it is quite unnecessary to do this in order to secure the best result. The two plants selected as parents are isolated as much as possible, and the flowers protected from insect visits. If the capitula are then rubbed together cross-fertilization is efifected in both of the possible way.s, seeds are set freely, and the parentage of the offspring is readily determined. All the seeds of a crossed head are used to produce a fresh colony of the next generation. Two kinds of plants are to be expected in this : — (a) plants like the mother produced by self-pollination, and (b) hybrids produced by the crossing. The hybrids when praecox is the mother plant are much larger and later plants than their pure-bred neighbours. In the large number of crosses so far made, there has never been any difficulty in distinguishing the hybrids soon after the plants are bedded out. When praecox is cue of the parents, the hybrids may often be A. H. Trow 245 distinguished at a very early stage. When two forms of the types NN aud RR are used for crossing, as in the cases under consideration, the ray florets in the hybrids are of the NR type and the previous recogni- tion is amply confirmed. Hybrids are formed quite readily in tliis way as Table II shews. TABLE II. Total No. No. of Percent, of plants Fi hybrids of Exp. Date Cross raised secured hybrids Exp. 9 190G Praecox x erectus, lailiatiis 16 9 56 Exp. 10 1906 Latifolius x erectus, radiatus 19 1 5 Exp. 11 1907 Multicaulis x erectus, radiatus 172 40 23 - Exp. 12 1909 Genevensis x erectus, radiatus 36 12 33 The number of hybrids produced averages 2.5 °l^. The F, plants derived from any cross are always very much alike and so are the pure-bred plants. In the beds the two types have invariably been very obvious, so much so that inexperienced visitors to the garden easily recognise them. Hence provided tliat both parents have been adequately protected there is no difficulty either (1) in raising hybrids or (2) being certain of their parentage. It is scarcely possible to secure absolute certainty as to the effectiveness of the isolation and protection, but generally there would be no great difficulty in recognising the introduction of some foreign strain by the agency of a misplaced pollen grain. There can only be doubt as to the paternal parentage. One must remember that the ordinary method of selfiug, involving castration, is at least as fallible as the one outlined above. Hence the labour of crossing individual flowers is not only tedious and unprofitable but unnecessary. Analysis of the F., generation. The second generation, so far as concerns the characters RR and NN, in the four crosses under con- sideration, is very easily analysed. In each case the three types of plant — RR, NN, and NR — are recognisable at the first glance. We have before us a very simple case of segregation without dominance, as the ray florets of the heterozygotes, A^R, are typical intermediates. With respect to the other characters, of which there are several, one finds, as a rule, even after days of analysis, a variety which seems at first to defy classification. For the present it will be well to confine our attention to the ray character. The results of the analysis are given in Table III. The only remarkable feature of this analysis is the constant tendency to a slight excess of NN forms. This may have some importance and is at any rate interesting, as the typical groundsel is also NN. Exp. Date Exp. 13 1908 Exp. 14 1908 Exp. 15 1909 Exp. 16 1911 246 Inheritance in the Groundsel TABLE III. Nos. actually found, Nos. calculated, q, , . distributed amongst distributed amongst lotal ^jjg three types the three types plants ' * ^ ' ^ ^ Type flowered NN ER NK NN BR NR i<'2 of praecox x erectus, radiatus .548 161 117 270 137 137 274 F.2 of latitoliu.s x erectus, radiatus 108 39 23 46 27 27 54 Fa of multicaulis X erectus, radiatus 401 121 122 218 115 115 230 F-> of geneveasis x erectus, radiatus 234 60 53 115 58 58 117 Totals ... 1351 387 315 049 337 337 075 The radiate groundsel of the Channel Islands. Mr Maiquand, to whom living specimens of e^-ectus, radiatus were forwarded, with a request that he would send back the corresponding Channel Islands form, obliged me by forwarding in April, 1907, several living specimens in fruit. These were, as he also recognised at that time, quite distinct from the Glamorgan erectus, radiatus. The ligulate ray florets (see PI. XVI, fig. 10 and text-figure 30, p. 274) are not only shorter and so less conspicuous, but more distinctly S-touthed at the ape.x. Moreover, the plants were nearly covered with a somewhat coarse type of hair, and hence distinguishable by that character alone from all the preceding types, which are glabrous. The plants had obviously been obtained from a sandy habitat and consequently it was anticipated that there would be some difficulty in raising normal colonies in the heavy soil of my garden. Exps. 17 and 1i"iJs. This constant hairy, radiate type has been named lanuginosus. It seemed desirable to test once more the inheritance of the RR character (and also of course its relations to other characters) in the hybrids between lanuginosus on the one hand and praecox, erectus and multicaulis on the other. It was certainly advisable to prcjiliice, if A. H. Trow 247 possible, a non -radiate lanuginosus. The necessary crosses were made in 1908 and the Fi generation was raised in 1909. The result appears in TABLE IV. Distribution between Exp. Cross Plants flowered Lanuginosus Hybrid t\ Per cent, of Hybrids Exp. 19 Lanuginosus x jiraecox 99 53 46 46 Exp. 20 Lanuginosus x erectus 100 61 39 39 Exp. 21 Lanuginosus x multicaulis 42 18 24 57 Totals 241 132 109 45 Owing to the ease with which ci'ossing talv.es place in this type, not anticipated, and of course unknown in 1908, an une.xpected result came to light with the flowering of the hybrids : sotne of these xuere of RR type. The re.'^ults were similar in each of the three cro.sses. In Exp. 19 (lanuginosus x praecox) witla 46 Hybrids there were 38 NR and 8 RR plants In Exp. 20 (lanuginosus x erectus) ,, 39 ,, 34 NR and 5 RR ,, In Exp. 21 (lanuginosus x multicaulis) ,, 23 ,, 20 .NJi and 3 iJ/J ,, As it was important to determine whether the appearance of the RR plants was due to inefficient selfing, and it was desirable for other reasons to repeat the experiment, the cross lanuginosus x praecox was again made in 1910 (Exp. 22) with plants very carefully isolated and protected in the greenhouse, with the result that, in 1911, 31 plants of the second generation were raised, cmd all of them were hybrid and the thirty which Jloiuered were of NR type. In this case praecox pollen completely supplanted the much more abundant pollen of lanuginosus. We have therefore, however vexatious the conclusion may be, no alter- native but to suppose that the mixture of RR and NR hybrids in the first three experiments was due to pollination with two kinds of pollen grain of R and N type respectively. It is of interest to note that these RR Fi hybrids had the large ray of erectus, radiatus and that the plants were of intermediate hairiness. The R pollen grains were probably already on the inadequately selfed NN plants used for pollination. The analysis of tlie F.^ and F^ generations of the NR hybrids. In these cases the analysis even of the ray character presents some diffi- culty. The RR type varies considerably, — some plants have rays as conspicuous as those of erectus, radiatus ; others have the rays of lanuginosus. The clue to the solution of the difficulty is furnished when one notices that hairiness appears to have a depressing influence 248 Inheritance in the Groxmdsel on the development of the ray florets. The ER plants, the original i^i hybrids, as well as those appearing in F„ and F.^, have the rays so feebly developed that each head must be examined under a lens. With this help and when sjiecial attention is paid to very hairy examples, the results need not be ambiguous. (See notes on the illustrations, p. 275 and PI. XV, figs. 25, 26, and 27.) There were seven beds altogether in 1910 and 1911 in which the segregation of the ray character could be followed, and the result of their examination is given in Exp. Cross Exp. 23 Lanuginosus x praecox Exp. 24 Lanuginosus x praecox Exp. 25 Lamigiuosus x erectus Exp, 26 LamiginosHs x erectus Exp. 27 Lanugiuosus x multicaulis Exp. 28 Lanuginosus x multicaulis Exp. 29 Lanuginosus X multicaulis Totals ... 702 185 173 344 175 175 350 The only noteworthy d(!viation from the normal ratio occurred in the last bed, where the plants were uniformly hairy (homozygous for hair) and where it might be suspected that some BR plants had been counted as NN. It is just possible (not probable) that some of the apparent iViV plants were in this case really heterozygous for the ray character. If R be taken as recessive in this case, we get the proportion for tliis bed of Dominant : Recessive :: 77 : 20. The complete result of the analysis of the segregation of the ray character is summarized in f lABLE V. Ye.ar Parent Type Plants flowered Nos. found, of the three types NN RR NR Nos. calculated, of the three types Gen. NN BB NB F., 1910 NR 83 22 26 35 21 21 42 i'\ 1911 NR 92 25 26 41 23 23 46 F; 1910 NR 88 22 23 43 22 22 44 Fs 1911 NR 92 17 23 52 23 23 46 F; 1910 NR 202 49 44 109 50 50 100 i-':, 1911,1) NR 48 12 11 25 12 12 24 ^3 1911,2, NR 97 38 20 39 24 24 48 Experiment Exp. 8. Table I. Exps. 13 to 16. Table III. Exps. 23 to 29. Table V. TABLE VI. Plants floweretl Nos. found of the three types Nos. calculated of the three types D.ate NN RR NR NN RR NR 1906 449 109 114 226 112 112 224 1908—11 1351 387 315 649 337 337 675 1910—11 702 185 178 344 175 175 350 Totals ... 2502 681 602 1219 625 625 1250 While these results prove that the radiate character is generally transmissible, they also shew that the theory of dominance has to be accepted with some reserve. The experimenter who analysed only the A. H. Trow 249 results summarized in Table III wciuld be impressed with the obvious rays of the NR plants, and adopting the theory of dominance would count the NR and RR types together, and regard R as dominant; but in the analysis of the results summarized in Table V, he might quite easily overlook the NR individuals altogether and ceunt them as NN, in which case he would be obliged to regard R as recessive. The association of the factors for hair and rays probably effects a reduction of the ray character. It appears then to be of little consequence whether we regard N or R as dominant, or neither. Whatever signs we adopt, the interpretation remains the same. The theory of domi- nance has probabl}' been often pushed too far. Under these circumstances it will suffice to choose the most convenient system of nomenclature. The simpler ratios associated with the theory of dominance often give the clearer view of the experimental results. Neither is it quite clear in such cases as these whether the presence and absence hypothesis strictly applies. The original type of flower in the Compositae was doubtless actinomorphic. In the section Tubuli- florae we recognise the introduction of the radiate character or zygo- morphy into the outer florets, and in the Liguliflorae, possibly the same character, certainly a similar character, into all the florets. At least two factors would be necessary to effect this. In the genus Seiiecio the presence of typical ray florets is the rule, but the common groundsel is generally described as non-radiate, the radiate type being regarded as a variety. The groundsel must have assumed its peculiar non-radiate character either by the loss of the factor for rays (absence) or by the acquisition of some new factor (presence) which made itself manifest by suppressing the rays. We have at present no experimental means of testing the relative value of these two hypotheses. It seems fairly certain however that the non-radiate type of the common groundsel is more recent than the radiate types found in the related species, Senecio viscosus, sqvalidus and sylvatious. Ad- mitting this, we are still unable to decide whether the radiate groundsels lannginosus and erectus, radiatus are newcomers or relicts of the older original type : they are apparently aggressive invading forms and are certainly, to a considerable extent, replacing the non- radiate forms. This kind of mutability is not confined to the common groundsel. In Senecio Jacobaea there is a comparatively rare non-radiate form. It is abundant in one part of Ireland, according to Praeger. Exp. 30. A single specimen was collected near Cardiff, and was cultivated in my 250 Inheritance in the Groundsel garden for two or three years, crosseil with a local radiate form in 1908, aud 48 plants were brought to the flowering stage in 1911. As the results of analysis are peculiar and difficult of interpretation, it is necessary to state that of the 112 specimens which were originally planted, 64 perished of a disease induced probably by the rich soil and close planting. The disease had no selective action ; it simply destroyed the plants in the middle of the bed. The 48 plants which matured consisted of two types : 24 were RR and 24 NR plants. The seed-bearing plant was certainly NN in appearance ; the pollen was from an ordinary RR plant specially introduced into the garden for the purpose of making this cross. The expectation was, as self-pollina- tion was not excluded, that a large number of non-radiate {NN) plants would be secured and a few Fi hybrids, NR in type. It was rashly assumed that the non- radiate type would produce non-radiate plants only, if selfed, as is invariably the case in non-radiate forms o{ Senecio vidgans. This ambiguous result may be tentatively explained by assuming (1) that the non-radiate (NN) plant produced equal numbers of R and N ovules, was indeed in reality a heterozygote (NR), and (2) that the pollen of the radiate type (RR) is prepotent and, in the presence of both types, is the only one that is effective. Accepting these assumptions, all the N ovules would be fertilized by R pollen grains and produce NR plants, and all the R ovules by R pollen grains and produce RR plants. The explanation is purely provisional, and not the only possible one. The experiment is recorded at this stage to show how necessary it is to avoid the inference that what is proved to be true for one species is also true for other.s, however closely allied the species may be. The ray character has hitherto been examined experimentally in Senecio vulgaris and *S'. Jacobaea only. Gentaurea nigra, as is well known to many botanists, possesses radiate and non-radiate forms, and the mode of occurrence of these in Glamorgan suggests that the ray character segregates as in the groundsel. Other similar variations are by no means infrequent in the Compositae, and are well worth in- vestigation by the experimental methods of genetics. The problem of the inlieritance of the ray character in groundsels can, however, be regarded as solved, and it seems desirable, with a view to securing uniformity and brevity of notation, to adopt the theory of dominance to the extent of using the signs RR, Rr and rr instead of RR, RN and NN for the three types of ray character. R signifies radiate, r non- radiate. A. H. Trow 251 Investigation of a Colour Character in the Flowehs. The colour of the mnlticaulis flowers was, in the first generation raised, appreciably different from that of the other forms, and it was described in 1908 {Flora of Glamorgan) as of " a soft yellow." It was not anticipated that so subtle a distinction wovdd admit of further analysis. However it can now be shewn that the ray florets may, in 'certain types at least, be either yellow or cream coloured, and that cream behaves towards yellow as a recessive. It will be of interest to produce the evidence fnr this statement, especially as it demonstrates that there must be a second factor which acts when present along with that for cream colour in such a way as to inhibit more or less completely the development of the cream-colour character. Exp. 15. Multicaulis was crossed by erectus, radiatus in 1907, and 461 plants of the F^ generation were examined in 1909. At a late .stage in the examination, some of the RR plants attracted notice on account of the cream colour of the flowers. At first the colour was not treated as a character deserving of much attention, especially as it was not perfectly uniform in all the cream-flowered individuals. The total number of creams of which a definite record was kept is five, but there were certainly more. Fortunately seeds were saved from the two most typical creams — Nos. 174 and 346. These plants, however, had not been properly selfed. The nature of the progeny of these two plants is given below in the form of genealogical tables. 1909. Fo. No. 174. Cream, not selfed. I . . .■ 1910. F^. E.rp. 31. 33 plants, o£ which 5 were NR hybrids due to ordinary crossing. 5 Deducting these, there were left 28 plants, all Cream, of which No. 5 was selfed. No. 5 I 1911. Fi. Exp. S'2. 47 plants, all cream. 1909. F.,. No. 346. Cream, inadequately selfed. I 1910. ^3. Erp.SS. 108 plants, of which 4 were J^iJ hybrids. 4 Deducting these, there were left 104 plants, all HE. I r 1 97 plants, Cream 7 plants. Yellow, no doubt due to the inadequate I selling. No. 8. Selfed. I 1911. F4. E.rp. 3i. id plants all cream. 252 Inheritance in the Groundsel These experiments indicate that cream is recessive to yellow ; the seven rogues in Exp. 33 must have been heterozygous for yellow and cream, and due to an accidental cross with a yellow RR form. Seeds were also saved from several of the yellow types of the F2 generation, and as it sometimes proved advisable (colour was not the sole problem under investigation) to select other parents than those originally selfed, the results must be read with the necessary caution. 1909. F., . No. 2. Yellow, selfed. I 1910. F3. Exj). 35. 108 plants. I r: — 1 85 yellows 23 creams ; of these Nos. 9 and 37 were selfed. I 1 I I No. 9. No. 37. Slight yellow tinge in cream, I I and tested for that reason. 1911. F^. Exps. 30 and 37. 49 plants, cream. 49 plants, cream. This result proves the dominance of yellow. No. 2 was clearly a heterozygote. Two other yellows, Nos. 24.3 and 297, were tested and proved to be homozygotes. The record for one is given below ; that for the other is similar. 1909. Fn. No. 297, yellow, not selfed. I 1910. F3 . Exp. 39. 30 plants, of which 3 were NR and were destroyed. 3 Deducting these, there were left 83 plants, all yellow, of which No. 34 was selfed. I No. 34. I 1911 F4. Exp. 40. 49 plants, all ydhm. We can now accept the following notation, GG, Gc, cc, for the three types found, cc signifies creams; 0(7 yellows. The progeny of a sixth plant, however, was the means of elucidating the cause of the rarity and variability of the creams in the i^j generation. If there is a factor X dominant over another *• and cream colour can only appear in the plant when cc is associated with arx, being wholly suppressed by XX and almost wholly by X.r, then it is clear that in a generation where these two pairs of factors are segregating normally, there will be one-fourth of the individuals of the type xw and one-fourth only of these xx individuals also of the type cc, and therefore one- A. H. Trow 253 sixteenth only of the individuals constituting the whole colony will be of the type xxcc. These xxcc plants will alone be pure creams. The progeny of this sixth plant is shewn below. 1909. fo. 1910. Fi. Exp. 41. No. 368 yellow, not selfed. 37 plants, of which 4 were NR and 2 others did not flower 6 Deducting these, there were left 31 plants I 24 yellows I 7 creams No. 13, selfed No. 30, selfed 1911. Fj. Exps. i2 and iS. 90 yellows, CC. No. 1 selfed. Exp. 44. 98 creams, {ccxx) 88 plants, which seemed at first all yellow. No. 96 was a typical cream, and close examination led to the dis- covery of three types of plant 7 Creams. (ccxx) Cream to Yellow, the colour difficult to estimate, but certainly with some cream. Xxcc 77 Yellows, the colour rather faint and some- times shewing a creamy tinge on the under side of the corolla As one-sixteenth of 88 may be taken as 6, the result corresponds fairly with the view that the recessive cream only appears as a definite character as the result of the association of the cream factor with some other recessive factor. At first, I suspected foliage-leaf colour to be concerned in producing this result, but the observations so far made seem to shew that cream-coloured flowers may appear on plants with either dark-green or yellow-green foliage leaves. For the present we must be content to assign to this unknown pair of factors the signs X and X. X, when f)resent, more or less prevents the development of the cream-coloured character. Mutation. A Fimbriate Type. The 461 plants of the F^ generation of multicaulis x erectus, radiatus (Exp. 15) included one plant — No. 43 — which was not only markedly unlike all the others, but unlike any other radiate groundsel that I had ever seen. The ray florets, in this case, were of the usual number, but Journ. of Gen. ii 18 254 Inheritance in the Gh'oimdsel instead of being veiy obscurely 3-toothed at the tip, the ligules were often divided down to the basal tubular portion into three (sometimes two) long narrow segments. The capitula, as a whole, thus acquire a tasselled or fimbriate character. (PL XVII, figs. 19 and 20.) The study of the inheritance of this character is beset with diffi- culties. Although these have not yet been surmounted, it will be of interest to record the results hitherto obtained. No. 43 was selfed and a few seeds ultimately collected. It was noteworthy that the basal branches of this plant produced normal flowers, causing me to suspect that the anomalous fimbriate appearance was due to Aphis attack. Fortunately the experiment wa,s carried on, and it was soon found that perfectly healthy plants quite free from Aphis might be fimbriate. The nature of the progeny of this plant is given in the following table : 1909. F.. . 1910. F3. Exp. 4.5. No. 43, fimbriate, sulfed. 17 plants, of these three were Rr plants. 3 Deducting these, there were left 14 plants, all RR 9 fimbriate I I No. 4 selfed I No ripe seeds obtainable. There- fore self-sterile 1911. Fj. Exps. idandil. I 5 non-fimbriate I No. 17 selfed. Exp. 47. Exp. 46. No. 6 not selfed 49 plants 47 plants, all nun-finibriate I 22 fimbriate 27 nou-fimbriate It is clear that the fimbriate character is inherited, and it may be assumed that a corresponding ftictor F suddenly dropped out of the constitution of the original plant. No. 43. The new character, repre- sented let us say by the recessive factor/", as far as known, does not occur in any other local form of Senecio. Yet it probably occurs in many Compo.sitae, e.g. in chrysanthemums. Ultimately time may be found to trace its development and to make the necessary comparative studies. In the meantime, we may safely assume that we have to deal in this case with a mutation (and possibly a segregation also). It is clear that the plants are either self-sterile or very infertile to their own pollen. In this connection it may be stated that on A. H. Trow 255 several occasions during this study of groundsels, the difficulty of self- sterility has been encountered. Exp. 48. In one case, that of a plant isolated in the greenhouse (it was a monstrosity with fused cotyledons and other malformations) which did not set a single seed, it was note- worthy that all the flowers wei'e long-styled. Examples of long-styled capitula are reproduced in PL XVII, figs. 16, 17 and 18. Long-styled flowers have been frequently observed during the last three years, and there is little doubt that the further study of them and their distribution will help to clear away several difficulties. In another case, which occurred in the F^ generation of lanuginosus x praecox, the plant was a giant, the only one of the kind, and provided with very large ray florets. Exp. 49. Yet not a single perfect seed was obtained from it, although ultimately exposed to the pollination of all the other plants in the garden. ' How are we to explain the results detailed in the table on page-254? The 47 non-fimbriate plants of the Fi generation, as well as the parent plant No. 17, were all clearly homozygous and FF plants. No. 6, one of the parents ($) of the 49 plants of the Fi generation, was certainly a,ff plant. If we suppose that the chance pollen grains which in this case effected 'pollination were either / (22) or F (27), we get an ex- planation of the mixed offspring. This provisional explanation is to be tested in 1912 by isolating two_^' plants and obtaining seed from them'. It is quite possible that the fimbriate character is such that we shall always get under ordinary conditions nearly equal numbers of_;y and FF individuals. We have to assume in this case that the ray character depends not only upon the factor / but also upon the en- vironment. The heredity would follow the same rule as prevails in teazels with twisted stems, and in_ other " umschlagende Sippen." Hairiness. Hairiness is one of the most interesting and puzzling of the characters which serve to define these elementary species of groundsel, and has been investigated sufficiently to justify the publication and discussion of some of the results. In the last edition of Koch's Synopsis, 1902, a single hairy variety is described under the name of sordidus, with the brief description " Pfl. ganz spinnwebig-woUig." Rouy, in the ' This was done, but the plants produced no ripe pollen. The 1912 examination leads simply to the conclusion that all the fimbriate plants are female ? . It remains doubtful whether it is possible to secure male fimbriate plants. 18—2 256 Inheritance in the Gronndsel Flore de France, 1903, recognises no hairy forms. Until colonies of lanuginosus had been grown in my own garden, I had assumed, like most other botanists, that hairiness in groundsels was the result of a more or less direct response to changes in the external conditions, be- longed, in short, to the category of modifications. Lanuginosus, however, is always very hairy, whatever the external conditions may be. It is almost certainly impossible to raise a colony of these plants in the glabrous condition. Most of the other types are normally so glabrous that hair can, as a rule, only be found by looking carefully for it. The most glabrous forms, however, produce a little hair in the leaf axils and the buds are consequently often slightly hairy. Such hair is, however, soon lost, and the plants appear to be, as indeed they practically are, quite glabrous. lu this sense praecox, genevensis, erectus, vmlticaulis, latifolins and erectus, radiatus are glabrous. Intermediate between these two types are two other forms of hairiness. In these hair is constantly to be found on most parts of the plant until full maturity is reached, when it generally becomes greatly reduced in amount. The hair, even when abundant, however, is never dense enough to mask the stem-colour, and appears white at a distance, as in lanuginosus, yet it is generally recognisable with certainty, except perhaps in very old plants. These forms of hairiness occur in several incompktely investigated types that have been cultivated for several years in the garden. We thus have to recognise four standards of hairiness : — (1) very hairy {H'^), as in lanuginosus ; (2) distinctly hairy {H-), as in three types from Burry Green, Hoiton, and Cross Common respectively ; (3) slightly hairy (//'), as in two types from Cardiff and St Bride's respectively, and (4.) the glabrous types (H"). (PI. XVIII, figs. 21, 22, 23 and 24.) Grown under constant conditions, side by side in the same garden, the standard of hairiness is maintained for generations. It naturally varies a little in response to seasonal changes, but as all the plants are subject to the same change, the same relative differences appear year after year. It may perhaps be advisable to put on record the extent of the experiments which have led to these generalizations. The lanuginosus type of hairiness is very distinct, and so is the glabrous condition of such types as praecox and erectus. The inter- mediate types — H'' and H' — are more variable. They are sufficiently definite to admit of classification when pure colonies are examined. When segregation of hair factors is taking place, however, it is almost A. H. Trow 257 impossible to arrange the forms in their respective groups with strict accuracy. The observations summarized in Table VII suffice to demonstrate that hairiness and its opposite are transmissible characters, and there- TABLE VII. standard of Hairiness Exp. Type Exp. 48 Lanuginosus H^ Exp. 49 Burry Green type H- Exp. 50 Horton type H~ Exp. 51 Cross Commou type H- Exp. 52 Cardiff type H' Exp. 53 St Bride's type H^ Exp. 54 Praecox H" Exp. 55 Ereotus, &c. IP No. of generations maintained in pure culture 3 3 3 3 5 (possible cross in 2nd generation) 3 6 a very long Date of tirst generation 1907 1909 1909 1909 1907 Years in whicli iiairiness was tested 3 2 last 2 last 2 last 1st and last 1909 1906 series of 2 last 6 experiments, the agreeing with those opposite praecox No. of plants examined 234 135 122 89 209 111 361 results fore probably represented in the constitution of tiiese plants by at least one pair of factors. We shall therefore make use of the signs HH, Hh, and /;// to represent the three types of constitution. Glabrous forms are hh. We shall find that the variability of the hairy character is due (1) to the influence of other factors, and (2) to a second pair of hair factors'. Exps. 19, 20 and 21. In 1908 lanuginosus was crossed hy praecox, erectus and riudticaulis. Lanuginosus is hairy {HH) and radiate {RR). The other three types are each glabrous (hh) and non-radiate (r?-). The objects in view were: — (1) to secure the non-radiate form of lanu- ginosus, (2) to secure hairy varieties of praecox, erectus and multicaulis, and to determine whether the hair factors could be transposed from type to type with the same facility as the ray factors, and (3) to note the effect on each other of the factors for hair and rays. The results were unexpected. At the close of the examination even of the F3 generations of these three crosses, it was still somewhat doubtful whether either of the first two objects had been secured: the third however had been investigated with at least considerable success. The F^ hybrids in each of these three crosses are of intermediate hairiness ; in the F^ generation segregation takes place, and at least three types of hairiness are noticeable. Taking the hairiness of the Fi hybrid as the standard, we find (1) some plants conforming to this, See notes to the illustrations for evidence of a third pair of hair factors. 258 Inheritance in the Groundsel while others are either (2) more, or (3) less hairy. Arranging the plants in three groups accordingly, and commencing our analysis with the F^ generations of three RR plants (probably the result of an accidental cross of lanuginosus by erectus, radiatus (see p. 247)), we get the following result : TABLE VIII. Cross Eay Character in Fi No. of Plants Types Exp. HH Hh hh E.'cp. 5G Lanuginosus x erectus, radiatus ? MR 108 21 51 35 Exp. 57 LauuginosuB x erectus, radiatus? RR 166 45 79 42 Exp. 58 Lanuginosus x erectus, radiatus? RR 160 41 78 41 Totals ... J Found 434 107 208 118 Expected 434 108 217 108 Segregation apparently takes place normally in each of these three cases. If we now examine in the same way the F„ generations of the three NR types of known parentage, we get the result shewn in TABLE IX. Cross Ray Character in Fy No. of Plants 'HH Types Exp. Hh ///, Exp. 23 Lanuginosus x praecox Rr 84 22 47 15 Exp. 25 Lanuginosus x erectus Rr 88 19 43 26 Exp. 27 Lanuginosus x multicaulis Rr 203 61 79 63 The result of Exp. 27 is clearly aberrant. Deferring its con- sideration, we may summarize the results in the other five experiments, thus : — Types Exp. No, of plants HH Hh Nos. 56, 57 and 58 434 108 208 Nos. 23 and 25 172 41 90 Totals ( Found I Expected 606 606 149 151 298 303 hh 118 41 159 151 No thoroughly satisfactory explanation can be given of the result in Exp. 27. Not only are the numbers very aberrant, but the mode of obtaining them is liable to criticism. All the HH plants were certainly more hairy than the original F^ heterozygote. There were certainly 61 HH plants present. But all the other plants had some hair, and at the first examination only 20 were marked as hh. Ex- tracting these and re-examining the remainder, this was found to A. H. Trow 259 include apparently two types more and less hairy respectively; the less hairy were added to the hh group, and the more hairy constituted the presumed Hh heterozygotes. Under these circumstances, it should be understood that the result shews little more than that segregation actually occurs in this case. The aberration is probably due to trans- gressive variability, which makes it impossible to fix exactly the limits of the three types. A nearer approximation is gained by applying the law of dominance, but this procedure reveals nothing new. All groundsels, even the most glabrous types, vary a little in hairiness, and in such sunny weather as that of last summer (1911) to a con- siderable extent. It is possible that the midticaidis strain introduced an unknown disturbing factor. We may now turn our attention to the relation of the factors for rays and hairiness when they act together. Lanuginosus {RRHH) xpraecox {rrhh), erectus {rrhh) or multicaulis {rrhh) might be expected to produce nine t3'pes of plants in the F„ generation. Table X shews both the expectation and what was actually found. TABLE X. Cross No. of plants flowered HH 9 Types )■;■ RR Hh hh Rr Exp. HH Eh "m BH Hh hh Exp. 23 Lanuginosus x praecox 83 Found 13! \ 10 3! 6 23 6 2 1 14 6! — Expected 5 10 5 10 21 10 5 10 5 Exp. 25 Lanuginosus x 1 88 Found 14! 8 1! 4 25 14 1! 10 11! erectus j" — Expected 5 11 5 11 22 11 5 11 5 Exp. 27 Lanuginosus x ) 202 Found 34! 6 3! 25 51 24 1! 22 26! multicaulis j" — Expected 12 2,5 12 25 50 25 12 25 12 Confining our explanations to Exps. 23 and 25, in which Hh and Rr taken separately segregate normally, we note that the heterozygotes for hair are distributed fairly, according to the usual law, among the three types RR, Rr and rr. There are, however, too many plants of HHRR type and too few of lihRR, and also too many plants of hhrr and too few of HHrr. In other words, hairy radiate types and smooth non-radiate types are produced in greater relative abundance than glabrous radiate or hairy non-radiate types. In Exp. 27, which although anomalous, agrees with Exps. 23 and 25 in these respects, only one plant was HHrr and could therefore be of the type of a hairy multicaulis or non-radiate lanuginosus. In Exp. 25 there was only one HHrr plant, and in Exp. 23 only two. Hence it is clear that the production of a hairy praecox, erectus or multicaidis, or of a non-radiate lanuginosus. 260 Inheritance in the Groundsel is a matter of difficulty, for the factors for hair and rays are by no means the only ones present. There are at least two possible explanations of this behaviour, viz. (1) that the four types of gamete RH, Rh, rH, rh are not produced in equal numbers — gametic coupling ; and (2) that whether produced in equal numbers or not, certain unions are preferred to others, e.g. RH X RH and rh x ?•/(. to r-H x rH or Rh x Rh. This is not an im- probable explanation, for certain combinations might easily have special advantages ; e.g. more rapid growth of the pollen tube or quicker response to the chemotactic stimulation of the ovule. Let us assume that R and H are really dominant, and simplify Table X to TABLE XL No. of plants 4 Types Eip. Cross raised HR Ut hll hr Exp. 23 Lanuginosus x piaecox 83 Found 52 IG 9 6 Katio 9:3:3:1 — Expected 4.5 15 15 5 Ratio 22 : 5 : 5 : 4 — Expected 51 11 11 9 Exp. 25 Lanuginosus X erectus 88 Found 51 11 15 11 Eatio 9:3: 3:1 — Expected 50 IG 10 55 Katio 22 : 5 :5 :4 — Expected 54 12 12 10 Exp. 27 Lanuginosus X multicaulis 202 Found 116 23 37 26 Eatio 9:3: :3 : 1 — Expected 113 37 37 12 Eatio 22 : 5 : 5:4 — Expected 123 28 28 22 Totals 373 Found 219 50 61 43 iatio 9:3:3:1 — Expected 210 70 70 23 ;atio 22 : 5 : 5 : 4 — Expected 228 52 52 41 The agreement with the latter ratio is remarkably close, and the inference may fairly be drawn that coupling takes place according to the system 2HR: IHr :lhR -.^hr. There is, however, more than this to be deduced from the experiments. The excess of HHRR plants suggests that the presence of R helps the factor H to assert itself more effectively in the development of the hair character. The analysis of the F^ generation of these lanuginosus hybrids made it desirable that further tests should be made by utilizing the F3 generation. The following cultures were therefore undertaken in 1911, with seeds produced on selfed plants of 1910 (F^). The three objects already described were still in view — to secure new hairy and non-radiate types, to test the general transmissibility of hairiness, and to determine the relationships of the factors for hair and rays — -but there was now a further one, viz. to test the accuracy of the A. H. Trow 261 analy.'sis of the F„ generation. It is well known that the .safest test (as well as the most troublesome) for a presumed heterozygote is to raise a colony of plants from it. Ten of the eleven colonies raised shewed that the constitution of the parent plants had been correctly estimated with respect to hairiness. TABLE XII. Eip. Culture No. for 19U Cross Hair type of parent Fj Hair type of progeny F3 Ray type of parent No. of plants required Exp. 59 28 1 hh — RR 100 Exp. 60 29 Lanugiuosus x praecox Eh Hh rr 100 Exp. 61 30 31 1 32 J HH HH Rr 100 Exp. 62 Exp. 63 Lanuginosus x erectus Hh HH HH HH rr Rr 100 100 Exp. 64 33 \ Hh Hh Rr 100 Exp. 65 34 Hh Hh rr 100 Exp. 66 35 Hh Hh RR 100 Exp. 67 36 Lanuginosus x multieaulis HH HH RR 50 Exp. 68 37 HH HH Rr 100 Exp. 69 38 • HH HH rr 100 Exp. 70 39 / HH HH RR 50 The eleventh (Exp. 62) marked Hh, proved to be constant for hairi- ness, all the F3 plants conforming to the standard H\ The plants were all rr; if we assume that the non-radiate condition has the effect of depressing hair development, we secure at least a provisional explanation of this case. The original analysis, however, becomes as a whole subject to an error of 10 °/^, and one must admit that the results are to be accepted only with such reservations. Let us now note the result of the examination of the segregation of the hair in the Hh types of Table XII, and take in order the rr, RR and Rr groups. The results are presented in Table XIII. The numbers accord fairly well with the expectations. The divergences are partly due to the attempt to recognise the heterozygotes. The most hairy types in No. 29 were as hairy as lanuginosus — in the three cultures Nos. 34, 35 and 33 this was not the case. We may assume that typical multieaulis carries a factor Y which depresses the development of the hair character. In its absence (y) hair is fully developed if the factor for hair, H, is present. Pure praecox is a yy plant, midticaulis is YY. This hypothesis will also enable us to explain the interesting result of Experiment 36. Two types of hairy plants appeared in this case : (a) very hairy — H^ — like lanuginosus, and (6) hairy— //=— like the HH plants of No. 35. The 13 very hairy 262 Inheritance in the Gh'oundsel TABLE XTII. Types Eip. Exp. 60 Exp. 65 Exp. 6G Exp. 67 Exp. 64 Wo. 29 34 35 Cross Lanuginosas x praecox Lanuginosus x multieaulis Lanuginosus x multieaulis Hair type Hh Hh Ray No. of - — type plants HH rr 97 22 90 23 Hh hh 49 26 44 23 36 Lanuginosus x multieaulis Hh RR 96 Hh RR 49 31 (H-) 33 32 Remarks Very hairy individuals present in HH The hair in HH plants relatively weak The hair in //// plants well developed The H^ plants as hairy as lanuginosus 33 Lanuginosus > multieaulis [ Hh Rr 49 14 20 15 Hair fairly well veloped de- plants were apparently of the same phy.siological constitution as lanu- ginosus— the soil did not suit them — the 36 hairy individuals were fairly well adapted to their environment. It was doubtless no accident that caused one-fourth of the plants of this colony to behave in this way. The plant selected as the parent for this colony happened to be an individual with the constitution Yy. The thirteen very hairy plants were yy in constitution. This explanation may possibly suffice to account for the occurrence of a certain percentage of weakly plants in other cultures derived from the cross lanuginosus x multieaulis. Tiiese weaklings are recognisable in the seed-pans and boxes, and invariably perish when planted out. May they not have been to a great extent the yy plants of the different generations ? They are always so hairy that the possi- bility has always been kept in mind that ill health in itself, whatever its cause, promotes hair development by its indirect influence on certain regulating factors. These weak, hairy plants were carefully grown and watched in 1912, and proved to be invariably long-styled and relatively infertile. Fig. 17, PI. XVII shews the capitulum of one of them. TABLE XIV. Variability in hairiness Exp. Culture No. Cross Hair type Ray tyiie m m H' Remarks Exp. 61 30 Lanuginosus x praecox HH Rr 34 i'llUR H)Rr : ( iRR 12 \ 21Rr ( ORR 3 iRr No n-plant was very hairy, although 2rr i21)-)- •2rr 2 were placed under H-' Exp. 63 32 Lanuginosus x 1 ereetus J HH Rr 0 92 0 Bather weak type of H- hair. Unaf- fected by segre- gation of Rr Exp. 6H 37 Lanuginosus ■• ^ multieaulis ) HH Rr 0 98 0 Hair tending to dis- appear with age ; unaii'ected by the segregation of Rr A. H. Trow 263 Let us now examine the variability of the hair character in the six remaining groups of Table XII, in which the parents were all homo- zygous for hair (HH). Table XIV gives the result for those groups whose parents were R7\ Table XV for those whose parents were MR or rr. In Exp. 61 the hairiness varies in degree, shewing the three grades H', H" and H\ and the RR, Rr and rr types are irregularly distributed amongst these. There are so few H^ types and these are so loosely distinguished from H- types that the colony may be arranged thus : — 92 plants I — I I 34H3 58H2 1 I 1 I — I 1 III ill 2'21tR WRr 2rr 4RR 31Rr 23n- The numbers, although 58 : 34 might represent 9 : 7, shew that there is apparently no real segregation of hair factors in this case. The difiSculty of arranging the plants in definite groups according to their hairiness supports this view. We have therefore to explain as best we can the remarkable association of RR and W, and rr and H-. We are perhaps justified in assuming that the greater type of hairiness — H' — is due to the association of the hair factor H with R. On this assumption HHRR plants should be very hairy and of the type H^, HHRr „ „ „ less hairy „ „ „ ,, H", and HHrr „ „ „ slightly hairy „ „ „ „ HK The facts revealed by Exp. 61 agree very well with this assumption. Applying the hypothesis to the explanation of the results of Exps. 63 and 68, we are at once met with a difficulty, the standard of hairiness is constant at the grade H" and the segregation of the ray character does not affect it. This difficulty may be removed by amplifying the original hypo- thesis. Let Z be an unknown factor which when present nullifies the stimulating effect oi R on H. Then, since the presence o{ R promotes hairiness in Exp. 61, praecox is probably a sz plant, and since the hair character is constant in Exps. 63 and 68, erectus and multicaulis are probably ZZ plants. Such a hypothesis is somewhat involved and perhaps unnecessary ; but as it explains the results hitherto obtained and can readily be tested 264 Inheritance in the Groundsel by experiment, it deserves provisional acceptance. It is possible that the presence of the Y factor alone in Exps. G3 and 68 might serve to explain the result. Further experiments are necessary. The remaining three experiments are of greater interest, as they were intended to test the behaviour of the progeny of plants homo- zygous for hair and rays. An unexpected segregation occurred in one of them. TABLE XV. Variability in hairiness Exp, Culture No. Cross Hair type Ray type H' H' HI Exp. 62 31 Lanuginosus x [ erectus J HH IT " " 93 ry Exp. 69 88 Lanuginosus x [ multicaulis J IIH rr ^Oyy in-y 271'! Exp. 70 39 Lanuginosus x multicaulis HH RR — 491'!' — Remarks Hairiness of the lowest type and constant. Hairiness probably de- pressed by IT 271'!' All H^ plants unhealthy. Hairiness upon the whole less than in the praecox cross. Exp. 61 Hairiness not quite equal to//'. Hence yy plants. R raises the grade of hairiness The plants of Exp. 62 were all of a very low standard of hairiness. This may be partly accounted for by the absence of R and the presence of F. Exp. 69 is comparable with Exp. 67. The Y factor is involved, and the heterozygotes are recognisable. The slight loss of hair may be due to the absence of R. The numbers found correspond very well to the expectation. Found :— YY : Yy : yy :: 27 : 49 : 20 Expected:— :: 24 : 48 : 24 In Exp. 70 the plants shewed constant hairiness ; they were probably of YY type, the presence of R raising the grade of hairiness from H^ The study of the inheritance of hair is no doubt incomplete ; but it is clear that (1) the transmissibility of hair from one type to another is possible ; (2) that two pairs of factors at least are involved, H, h and Y, y ; (3) that consequently there must be at least several grades of hairiness ; and (4) the pre.sence {R) or absence (r) of the ray factors modifies the hairiness due to the proper hair factors. The difficulties of the study are accentuated by the transgressive variability of tlie segregating characters and by the direct influence of the environment in producing slight non-heritable modifications. A. H. Trow 265 Observations on Stem Colour. At an early date in the course of these experiments it was noted that some of the pure tyj^es were green-stemmed, viz. erectus, erect us, radiatus and multicaulis; others had stems which were more or less reddish in colour, viz. praecox, genevensis and lanuginosus. No attempt was made to study the behaviour of this pair of characters in segregation until 1911, when certain families of the F^ generation of the crosses lanuginosus x erectus and lanuginosus x multicaulis were found to consist either of green-stemmed individuals only, of red-stemmed individuals only, or of individuals of several types of stem-colour. It seemed that stem-colour varied independently of the other characters under investi- gation, and was therefore probably represented by definite factors in the constitution of the plants. There are very great difficulties in arranging the plants in definite categories according to stem-colour, for green-stemmed plants tend, under certain conditions (exposure), to develop some red colour, and red-stemmed plants lose some of their red colour in shade. Moreover, the red-stemmed types are not red-stemmed throughout — the upper internodes are apt to be green, although these parts are subject to the most intense illumination. Green-stemmed plants, if they develop red colour at all, do so most freely on the lowest internodes. Let GG denote red-stemmed and gg green-stemmed plants. When G is present (GG) and certain standard conditions are maintained, at least one-half of the main axis should be of a reddish colour ; if (? is absent (gg), there should be little more than traces of red colour except at the very base of the main stem ; the intermediate condition (Gg) is represented by varying degrees of redness, both as regards the intensity of the colour and its extent. The pure types grown in adjacent beds under similar conditions furnish a convenient standard of reference. Perhaps the simplest proof of the existence of factors for stem colour is furnished by the investigation of the i^, generation of genevensis X erectus, radiatus. Both parent plants are glabrous, but differ with respect to two pairs of characters. Genevensis is red-stemmed and non- radiate (GGrr) ; erectus, radiatus is green-stemmed and radiate (ggRR). Exp. 16. A colony of 234 plants was raised and brought to the flowering stage without the loss of a single plant. 266 Inheritance in the Groundsel Segregation took place as follows : — For stem colour:— GG : Gg : gg :: 53 : 124 : 57 For the ray character : — RR : R?- : rr :: 53 : 115 : 6G The expectation in eacli case was :: 58 : 117 : 58 But nine types should be present in the F., generation. If these occur in the expected proportion, we have a fair proof that there are two pairs of factors and that they not only segregate normally, but that the method of investigation is fairly accurate. Table XVI gives the result of the analysis made from this point of view. TABLE XVI. RR Rr rr GG Ga 'I'J GG Gu mi GG Grj an Nos. found 10 30 13 28 57 oO 15 37 11 Nos. calculated 15 29 15 29 58 29 15 29 15 Differences -5 +1 -2 -1 -1 +1 0 +8 -1 The approximation is as close as could be reasonably expected. The greatest difference amounts to a divergence of 33 "/^. A similar result was obtained with the F, generation of the cross lanuginosus x erectus, the F„ parent plant having apparently the con- stitution HHYYRrGg. The F^ generation in this case consisted of 92 plants, and the segregation proved to be as follows : — For the ray character :—i?i? : Rr : rr :: 23 : 52 : 17 For stem colour :— GG : Gg : gg :: 20 : 4^S : 24 For both characters, see Table XVII. TABLE XVII. GG Gg tig (VG Gg .,„, „„ ,,. ._ 7 : 1 : 1 : 7in onesex. Ratio:— S'9 : 9 : 9 : 7 | "'"^ "" '^ *' Further experiments are necessary to determine which of these forms of coupling is actually operative in such cases. In Primula, such experiments would be comparatively easy ; in Senecio, they would be somewhat difficult If the Fi plants are crossed with the recessive parents, thus (1) F, ? (HRhr) X P (/ (hr) and (2) P ? (hr) x F, J' (HRhr), ER Er hR hr 128 36 :3i 18 132 32 25 26 260 68 56 44 262 59 59 48 A. H. Trow 273 we should expect in each case (if the coupling occurs in both sexes in the form 2:1:1:2) families of the constitution 2HR : iHr : IhR : 2hr. If, however, coupling occurs in one sex only in the form 7:1:1:7, one family should have the constitution IHR : \Hr : IhR : Ihr, and the other the constitution IHR : IHr : IhR : Ihr. In Senecio, the ^i $ plants would need isolation, and the bisexual disc-florets would have to be removed while in bud. The P ^ plants unfortunately have no J flowers, and it is practically impossible to remove the stamens without injury to, or accidental pollination of, the stigmas. It would therefore be necessary to allow self- and cross- pollination to take place, and to allow for the additional hr types produced by self-pollination. The ratios to be looked for are : — 2:1:1:2; 7:1:1:7; 1:1:1:1; 2:1:1:2-1- a;; 7:1:1:7+*; and l:l:l:l-f a;, where x represents the additional hr types produced by self-pollination. In Primula, where the necessary castrations are easily made, the three ratios 2:1:1:2, 7:1:1:7 and 1:1:1:1 should alone occur. Small families of 16 to 32 plants should suffice to determine the type of ratio. I regret to say, however, that the pure strain of lanuginosus has become so weak and unhealthy — perhaps by successive selfings — that it is no longer available for experiment. The experimental proof in the case oi Senecio cannot be furnished before the end of 1915 \ The assumption of dominance, although often of great assistance, as in this case, in giving a clear and condensed view of an experimental result, often tends to obscure facts of importance. The nine types which result from the interaction of two pairs of characters are, I think, recognisable in these cultures. The following table gives the numbers found and the expectation on the assumption of coupling of the form 2:1:1:2 in both sexes. Compare also Table X, p. 259. RR Rr rr BB Eh hh EB Eh hh BE Eh hh Culture 23 35 11 1 15 67 30 3 33 18 Culture 24 47 5 0 17 63 25 2 30 26 Total (23 and 24) ... 82 16 1! 32 130 55 5 ! 63 44 Expectation. Coupling of the form 2:1:1:2 48 48 12 48 119 48 12 48 48 • I find that Gregory (Proc. Roy. Soc. B., Vol. 84, p. 14) has made the necessary crosses and proved that coupling takes place in each sex. The exact form of the coupling, however, still remains somewhat uncertain. Primula sinensis appears to be a somewhat difficult type for such a determination. Upon the whole, the evidence clearly points to the occurrence in this case of the 2:1:1:2 ratio in each sex. 274 Inheritance in the Grotmdsel Some of the discrepancies may be due to the difficulty of recogaisiug the various types. RRhh plants cannot however be mistaken, yet there was only one and not 12 as expected. Although five plants are marked rrHH, not one of these was a typical non-radiate lanuginosus — the production of which was one of the chief objects of the experiment. The single RRhh plant was a perfect example of a radiate praecox. Treating // as dominant over h, the table becomes HH and Hh hh HH ami Hh hh HH and Hh ;,/, 98 1 162 55 68 44 96 12 167 48 60 48 Found Expected ... Treating H and R as dominant over /( and r, we get (compare Table XI) : n h E h 2G0 56 68 44 263 GO 60 48 Found Expected . . . The process gets rid of all discrepancies of importance, but at the same time obscures the very important facts revealed by the fuller analysis — the great dearth o{ RRIih and rrHH plants. This is a point of interest to which students of genetics might pay greater attention. Now that the heterozygotic forms are being more acutely studied, it is probable that many similar results will be brought to light and help to increase materially our knowledge of the actual mechanism of segregation. ■ ^ ;i 1 ■ . T Fig. 28. nn X 3 Fig. 29. Rr x 3 Fig. 30. Er x 3 Fig. 31. rr x 3 Enlarged drawings of individual flowers Iiy Miss M. Brockington. Fig. 28 — a ray floret of erectus, radiatus, RR ; Figs. 29 and 30 — ray florets of the hybrids praecox x erectns, railiatus and lunupiiiosus x erectus respectively, Rr; Fig. 31 — a disc floret of erectus, rr. Note the presence of the five corolla lobes in Fig. 30. A. H. Trow 275 NOTES ON THE ILLUSTRATIONS (Plates XV XVIII). All the photographs were prepared from the crops of 1912, which includeil colonies of all the types refeiTed to in the paper. Certain new features of interest were observed for the tirst time in lyl2, such as the unexpected appearance of the single specimen of a cream coloured, Jiiiihriale, multicaulis represented in Fig. "20, PI. XVII. These are reserved for furtlier consideration and a later rejiort. Two points, dealing with the ray character and hairiness, deserve a brief notice here. The examination of two large colonies of the F2 generation of the cross lanuginosus x praecox shewed that there were present m each, two distinct RR types (Figs. 7 and 10, PI. XVI.) and three Rr types (Figs. 25, 26 and 27, PI. XV.). The difference in the degree of ray development is due doubtless to the presence or absence of the hair factors. Comparison of the figures 25, 20, 27, and of the figures 3, 4, 7, 8, 9, 10, and 11, will prove that the character due to the presence of the same factor may be a variable one. The examination of the F^ generations of the cross lanitfiinosits x muIticauUs, in the current year (1912), led to the conclusion that the four types of hairiness referred to as Hi,, Hi, H-i, and i/3 are mainly due to the existence of three factors for hairiness. In addition to H and Y there is a third factor which made itself evident by certain colonies from a H-^ parent segregating in tlie proportion ffj : Hj :: 3 : 1. Ho, Hi, and H-^ plants do not segregate apparently; Hiy = hh, Hi = HHDD, where D represents the third hair factor, H3 = HHyy. ifj ni^y be homozygotic and is then probably always ffif IT. It is often heterozygotic, and may throw either H\ or i/3 plants, but not both, in the proportions //] : Ko :: 3 : 1 or i/o: JI3 :: 1 : 3. It must not be forgotten that other factors apparently infiuence the development of hair (see p. 263). Fig. 1. Praecox. 45 days old, photographed as it commenced to flower. The neck of the flask seen in Figs. 1, 2, and 3 is 26 mm. in diameter. The whole plant is practically glabrous. Fig. 2. Lanuginosus. 103 days old, photographed as it commenced to flower. The whole plant is very hairy. The flowers are not easily recognisable in the illustration. Most botanists will, I think, be prepared ultimately to concede specific rank to the two types shewn in Figs. 1 and 2. Fig. 3. One of the H2 types of Exp. 67, specially remarkable for the peculiar character of the rays, which were originally recorded as Rr? but proved to be RR. A single head is shewn enlarged as Fig. 11. It will be noted that the plant differs in other respects from praecox and lanurjinosus. Figs. 4, 5, and 6. Microphotographs of single capitula of mufticauUs, radiatus, multicaulis, radiatus x ynulticaulis, and multicaulis. Kadiate and non-radiate forms, if glabrous, produce in all the generations one type of heterozj'gote only, that represented in Fig. 5. All the microphotographs in Plates XV — XVIII, are magnified about four diameters. Figs. 7, 8, and 9. The radiate forms ol praecox, erectus, and generensis. Fig. 10. Capitulum of lanuginosus. Fig. 11. Capitulum with peculiar RR rays, liable to be mistaken for the Rr type. Com- pare this with Fig. 25, which is that of a Rr head. Figs. 12, 13, 14, and 15. Side views of capitula of multicatdis, praecox, erectus, and genevensis to shew size and shape of capitula and normal length of styles. Such types set seed freely when selfed. 276 Inheritance in the Groundsel Figs. 16, 17, and 18. Various long-styled types. These are very sterile, if selfed, but fertile to their own pollen, yielding seed quite freely when pollinated artificially with their own pollen or that of neighbouring long- or short-styled capitula. The eapitulum represented in Fig. 16 was taken from an ordinary plant of genevenHs. Fig. 17 illus- trates the type of head alone found in the sickly, hairy, individuals referred to on p. 262, and was taken from an individual of the F-> generation of lanuginosus xpraecox. Fig. 18 was taken from a plant which may almost be described as a non-radiate lanugi- nosiis {Fi generation oS hiniiginosus x miilticaulis). Fig. 19. Ululticaulix flmbriutiis, yellow. Fig. 20. Multicaulis Jimbriatus, cream. Both these are apparently S3), and evidence in favour of this hypothesis has been put forward by many observers — F. Keeblb and E. F. Armstrong 279 particularly by Palladin and Miss Wheldale. The latter investigator (1910 loc. cit.) has formulated in a clear and schematic manner the following hypothesis as to the course of events which leads to the formation of pigment in plants. The colourless chromogen by the oxidation of which pigment is produced occurs in the plant as the constituent of a g-lucoside. In this combined form it resists oxidation. Enzymes of the cmulsin type hydrolyse the glucoside and liberate chromogen which is then oxidised by atmospheric oxygen made active by the oxydase. Thus an anthocyan or soluble sap pigment is formed. Such anthocyan pigments, which are common in the flowers and other parts of plants, are of very different chemical constitution and origin from the plastid pigments which are also of common occurrence. We are concerned here only with the former. The anthocyan pigments are generally red, violet or blue. The chemical nature of the anthocyan pigments is obscure. They are regarded by Miss Wheldale as flavone derivatives which are known to be widely distributed in plants in the form of glucosides. An illuminating paper suggesting a mode of formation of organic pigment has been published recently by Chodat (1912). He shows that when tyrosinase acts on ja-cresol in the presence of one or other of the products of protein hydrolysis a series of diversely coloured pigments resembling the natural pigments is produced. Chodat believes that a pigment of a given kind is produced by the action (1) of an oxydase on (2) a phenolic compound in the presence of (3) an amino compound, and suggests that, as the compositions of the phenolic compound and the amino compound vary, so the composition and hence the colour of the pigment varies. Gortner (1910 and 1911) working independently has already pub- lished conclusions which in some respects are similar to those of Chodat. In a series of valuable papers Gortner has produced evidence in support of the view, put forward previously by Miss Durham (1904) and other observers, that the black or brown melanin pigments of animals are formed by the action of tyrosinase on a product of protein hydrolysis, namely tyrosine. He holds further, as described in the text, p. 299, that inhibition of pigment formation may be bi'ought about by the con- version of part of the tyrosine into a closely allied substance which is not only itself resistant to tyrosinase but also checks the action of that substance on tyrosine. Gortner applies this hypothesis to the elucidation of the suppression of pigment which is known on genetical grounds to occur in certain white forms of plants and animals. 280 Oxydases and Pigments of Plants Such forms have been investigated by Bateson and are described as dominant whites. Although they may be identical in appearance with true albinos they differ fundamentally from the latter in gametic com- position and hence in geuetical behaviour. The true albino lacks colour, the dominant white possesses the power of pigment formation, but that power is held in abeyance by an inhibitor. Inasmuch as the phenomenon of dominant whiteness is dealt with somewhat fully in the text, we need not devote attention to it here, beyond remarking that attempts to demonstrate by chemical means the truth of the Mendelian hypothesis with respect to dominant whites have not as yet been wholly successful. Miss Wheldale (1910), whose researches have contributed so much to our knowledge of this subject, regards inhibition as due to the action of deoxidising substances such as sugars, tannins, and the like, and has brought forward experimental evidence in favour of this opinion. In cases of partial inhibition, which is illustrated in P. sinensis by the dominance of pale over more deeply coloured varieties, it is suggested that the effect is due to a reductase. Methods. The methods in general use for detecting the presence of oxydase in plants depend on the addition of a colourless chromogen to the solution or extract obtained from the plant. If the result of the operation is to produce a pigment it is concluded that oxydase is present. If the pigment be produced only after the addition of hydrogen peroxide the oxidising substance is described as a pero.xydase. The method has many disadvantages. Certain of the cliromogens used as tests for oxydases undergo oxidation with more or less rapidity when exposed to the air. The extract or solution may contain reducing or inhibitory substances which interfere with the reaction, and in any case the localisation of the oxydase in the tissues of the plant is wellnigh impossible by this method. Clark (1911) has carried out recently an elaborate series of tests with different chromogens and finds that certain of them may be used for the microchemical determination of oxydase in plant tissues. Among the reagents used by Clark are guaiacum, phenolphthalein and ot-naphthol. Pyrogallol in the presence of glucose is employed by Chodat. Schreiner has obtained valuable results with respect to the oxydases of living roots by the use of benzidine. » F. Keeble and E. F. Armstrong 281 As the result of an extended trial of the many reagents which have been employed for the purpose of demonstrating oxydase we find that the most serviceable for our purpose are a-naphthol and benzidine. We make use of the fact demonstrated by one of us (Armstrong, 1910) that substances dissolved in alcohol penetrate rapidly into plant cells, and the method which we employ is as follows : In the case of benzidine, a 1 per cent, solution is made in 50 per cent, alcohol which is then diluted with so much water as not to cause a precipitate. The object to be examined, for example, an intact corolla or a section of a petal of P. sinensis, is taken from the plant and placed immediately in the reagent in a corked specimen tube. The tube is incubated at 37° C, and if no direct oxydase reaction is obtained the material is removed from the tube, washed lightly with water and treated with 1 to 2 drops of 10 vols, hydrogen peroxide, or the latter reagent may be added directly to the tube containing benzidine. In the case of a-naphthol, the solution may be used of even less alcoholic strength. Sections may be prepared either with a dry razor or with one moistened with a solution of cane sugar of suitable strength. No inhibitory action appears to be produced by this substance. The first effect of treating coloured flowers with either of these reagents is a decolourisation of the pigmented parts. This decolourisation appears to be due to the action of a catalase, but we have not made it a subject of special investigation. As we show in detail in Section II. the result of treating a coloured or recessive white flower of Primula sinensis is the demonstration of peroxydase in the epidermal layer of the petals and also in the bundle sheath which surrounds and accompanies the veins in their finest ramifications. Preparations of a considerable degree of permanence may be made for demonstration purposes in the following manner: — The flower in which the oxydase reaction has developed is washed well in running water, the corolla tube is cut away, the pietals floated on water, whence they are transferred by means of filter paper to a glass lantern slide. The superfluous water is removed by means of filter paper, and dry filter papers are placed over the flattened flower. A glass slide is laid on the filter paper, the preparation is placed in the incubator at 37° C. and pressed down by means of a weight. After a day or two, when the preparation has become dry, it is treated as a lantern slide, bound and kept in a dark place. The degree of permanence seems to depend first, on the thoroughness with which the preparations are washed. 282 Oxydases and Pigments of Plants and second, on the extent to which they are preserved from the access of light. Many of our preparations with benzidine retain their colour for months, but the colours produced by the use of a-naphthol may show signs of fading within a sliorter perind. Sections may be mounted either in glycerine jelly or may be taken up rapidly through the alcohols and mounted in Canada balsam. In the case of large objects such as fruits the reagent may be painted on to the surface to be studied and the reaction examined by reflected light. It is noteworthy that, as we show in the text and illustrate in Figs. 4 and 5, Plate XIX, the only reagent which gives a satisfactory reaction with the epidermal oxydase is benzidine, and that benzidine and a-naphthol discriminate as it were between epidermal and bundle oxydases. The former is picked out by benzidine but is untouched or almost untouched by a-naphthol. Tiie latter gives strong reactions with a-naphthol and benzidine. The behaviour of a-naphthylamine is very similar to that of a-naphthol. The colour of the reaction with benzidine is a rich brown due to the deposition of the oxidised product in the cells. Under certain circum- stances, and in early stages, this reagent produces a blue or blue-green colour which however passes more or less rapidly into brown. The i-eactiou with a-naphthol takes the form of a delicate lilac blue or lavender colour, and that with a-naphthylamine, a pink. It remains to mention that the i-eagents should be made up fresh for use and that the flowers or other subjects to be investigated should be fresh, uninjured, and in good growing condition. Late formed flowers, for example, are apt to give uncertain results and this is in conformity with the fact that such flovvers show often considerable departure from their normal colouration. The length of time of exposure to the several reagents varies with the object and can be decided only by trial. In the case of sections, the reaction takes place almost immediately ; but solid objects such as whole corollas require to be incubated for 1, 2 or more hours. F. Kbeblb and E. F. Armstrong 283 II. The Distribution of Oxydases ^ in Plant Tissues. A. The Oxydases in the Vegetative Members of P. sine7isis. The metliods described in the previous section permit of the mapping out of oxydases in the tissues of a plant with very considerable accuracy. Hence it should be possible, by determining the distribution of pigment and of oxydase in a given species, to obtain evidence as to the validity of the hypothesis that the formation of anthocyan pigment depends on the action of an oxydase on a chromogen. For. if oxydase is specifically concerned in pigment formation a certain parallelism is to be expected between the distributions of pigment and of oxydase. Before describing the results of our observations on the localisation of oxydase in the tissues oi Pi'imula sinensis it is nece.ssary to point out that we must not expect to find an exact coincidence of pigment and oxydase in each and every variety of this species. For, as shown by Bateson, Gregory, and others, the range of pigmentation in both vegetative and floral members of P. sinensis is very considerable. Some varieties have white flowers and others have coloured flowers of widely differing depths and shades ; some varieties possess green stems, others reddish stems, and others, again, deep red stems. Certain white-flowered, green-stemmed varieties, such for example as Snow Drift (see Gregory, 1911) are lacking altogether in anthocyan pigment. In other green-stemmed varieties the small amount of sap- pigment which they contain is confined to special parts of the plant, for example the roots, root-stocks, and bases of the petioles where it occurs either in the epidermal cells only or in the sub-ej^idermal cells as well. Of such minimally pigmented varieties, some possess no pigment in their other vegetative parts, for example the flower-peduncle, others, for instance. Sirdars, contain anthocyan pigment in isolated epidermal and sub-epidermal cells of the flower-peduncle. Between the pure green-stemmed varieties and those with reddish stems is a series of forms characterised by a progressively widening distribution of epidermal pigment in the vegetative members ; and in the reddish stemmed plants the pigmentation is wellnigh continuous throughout the epidermal layer. At the other end of the colour series are the dark red-stemmed varieties in which anthocyan pigment is ' For the sake of brevity we use tbe term oxydase to connote both peroxydase and oxydase and reserve for snb-section G (p. 304) the description of the distribution of these bodies in the several tissues. 284 Oxydases and Pigments of Plants much more widely distributed than in the green and reddisli stemmed forms. For example the flower-peduncle of the dark red-stemmed variety Mt. Blanc Star contains pigment not only in the epidermis and in three or more outer layers of the cortex but also in the tissues of the stele (vascular cylinder). If the investigator has these facts of variety of pigment distribution in mind he will not be surprised to discover when he proceeds to determine the distribution of oxydase that, although oxydase is present in every pigmented cell, it is not necessarily confined to these cells. This fact might appear at first sight to militate against the hypothesis which associates pigment formation with oxydase action ; but further consideration shows that it does not. For it is evident that oxydase and chromogen, though they interact to form pigment, may be produced independently one of the other and therefore the failme of certain tissues, rich in oxydase, to produce pigment may well be due to the absence of chromogen. Or, to express the idea in other terms, chromogen and not oxydase is the factor the lack of which limits pigmentation in P. sinensis. The evidence offered b}' the known facts of the Genetics of this species lends weighty support to this conclusion and indeed leads directly to the expectation that one of the two agents concerned in the production of anthocyan pigment is more generally distributed than the other. For if the two agents, chromogen and oxydase, were equally sus- ceptible of restriction of distribution in the plant then it would be reasonable to expect that two types of green-stemmed plant exist; one, green-stemmed because it lacks chromogen, the other, because it lacks oxydase. In point of fact, and in spite of the large amount of breeding work which has been carried out with this species, only one type of green-stemmed plant is known in P. sinensis. The evidence from Genetics in support of this statement is clear. Some plants, for example Stocks and Sweet Peas, show by their genetical behaviour that either of two factors for pigment production may be lacking from a variety. In such plants, as Bateson, Miss Saunders and Punnett (1906) have proved, it is possible, by mating white-flowered individuals of the two types, to bring the complementary colour factors together and thus to produce a reversionary, coloured F^ generation. But with P. sinensis a like result has never been obtained. A pure green-stemmed variety mated with any other similar variety gives rise to a green-stemmed Fi generation, and pure breeding white-flowered varieties, each of which F. Kbeblb and E. F. Armstrong 285 lacks a factor for colour, give rise when crossed with one another to white-flowered offspring only. The simultaneous study of the genetical behaviour of P. sinensis and of the distribution of oxydases in the tissues of the plant provides an explanation of this behaviour. For the latter line of inquiry demon- strates that all varieties of P. sinensis, including the pure green-stemmed varieties, contain oxydase in certain of their tissues. Whence it follows that at least enough oxydase for a definite amount of pigment pro- duction is a possession common to all Chinese primroses. We have in this fact the explanation of the failure of green-stemmed varieties to yield a red-stemmed F^ when crossed with one another. It is also clear why the cross, green-stemmed variety by reddish-stemmed variety, yields a reddish-stemmed F^ generation. Thus if we represent the chromogen producing factor by C, its absence by c, and the oxydase producing factor by O, and its absence by o, then green stem x reddish stem = Oc X OC, and P, = OOCc, and since both chromogen and oxydase are present in F^ the plants of that generation are pigmented. F^ plants of this kind produce gametes OC and Oc, and hence when such plants are self-fertilised the F. generation is of the typical mono- hybrid kind and consists of 30C : lOc, i.e. 3 reddish-stemmed plants: 1 green-stemmed plant. As we shall show immediately there is a similar agreement between the results of genetical inquiry and those obtained from the study of oxydase distribution in the case of red-stemmed varieties. But the broad features of the relation between oxydase and pigment may be seen in an equally striking manner when they are viewed from another .standpoint. If, instead of fixing our attention on one variety only, we consider the distribution of pigment and oxydase in the different coloured varieties we obtain clear evidence of the truth of the hypothesis that oxydases play a part in pigment formation. For when we adopt this procedure we discover that, as we pass stage by stage from the less pigmented to the more pigmented forms, the new additions of pigment occur in those tissues which in unpigmented and pigmented forms alike are most generally rich in oxydase. In other words, the cells which in general contain most oxydase are prepotentially pigment forming cells. Thus, although in pure green-stemmed varieties neither the ordinary Journ. of Gen. it 20 286 Oxydases and Pigments of Plants epidermal cells nor those of the epidermal hairs contain pigment, these elements give pronounced oxydase-reactions and they constitute the tissue to which pigment is confined in those pale reddish-stemmed varieties which have a minimum of pigment. Next to the epidermis, the sub-epidermal layer is, of all tissues outside the stele, richest in oxydase, and it is in the sub-epidermal layer that pigment occurs in the varieties somewhat more jjigmented than those which belong to the category of pale reddish-stemmed forms. In the case of green- stemmed and reddish-stemmed varieties, the distribution of oxydase in a member of the series is indicative of the distribution of pigment in the next higher member of that series. It is only in dark red-stemmed varieties, e.g. Mt. Blanc Star, that the pigment extends to any considerable depth into the cortex. These varieties are remarkable also for the fact that their anthocyan pig- ments are not limited to the epidermal and cortical tissues systems, but occur also in those of the stele (vascular cylinder). As is the case with all pigmented tissues of the epidermis and cortex, the pigmented tissues of the stele give clear evidence of a high oxydase content. Therefore we have a further means of testing the hypothesis ; for by analogy with the distribution of oxydase in the progressively less pigmented members of the colour series we may expect to find that the localisation of oxydase in those forms which are without pigment in their stelar tissues coincides with that of the pigment in the corre- sponding tissues of the dark red forms. Appropriate examination shows that this anticipation is realised. For example, the pigment in the stelar tissues of the flower-peduncle of a dark red-stemmed plant occurs in the pericycle and in patches of pith cells which lie against the protoxylems of the wood ; and these, together with the phloem, are the tissues which are rich in oxydase. In the root of a dark red-stemmed plant, large quantities of pigment occur in the pericycle, in the medullary rays which extend from near the periphery of the stele almost to the centre, and also in the phloem. The distribution of oxydase in the stele of the green and reddish varieties is very similar to that of the pigment of the red varieties. Thus the flower-peduncle of a green-stemmed plant contains oxydase in considerable quantity in the pericycle, phloem, and in the pith cells which abut on the protoxylems. We conclude therefore that those tissues which in non-pigmented forms are richest in oxydase are the tissues in which in coloured forms pigment makes its appearance. F. Kbeble, and E. F. Armstrong 287 Although there can be no doubt but that this broad relation exists between oxydase and potentiality of pigment formation, it is not to be concluded that all varieties of P. sinensis have identical oxydase content. Simple observations and experiments suffice to show that the extent of distribution of oxydase differs in different varieties. For example, in the superficial tissues of the flower-peduncle of Sirdar, oxydase is limited exclusively or almost exclusively to the epidermal layer; whereas the corresponding tissues of other green-stemmed varieties give a well marked oxydase reaction in bobh epidermal and sub-epidermal layers. There is good reason to believe that chloroplasts act as inhibitors of oxydase -formation in a cell and it is noteworthy that the sub-epidermal layer of Sirdar is specially rich in chloroplasts. Again in red-stemmed varieties, the petioles, which together with the roots appear to be the members richest in oxydase, are so rich in both chromogen and oxydase that pigment occurs in practically every cell ; in green-stemmed plants, though the roots are rich in oxydase, the cortical cells of the petioles give no oxydase reaction. These phenomena and others to be referred to immediately lead us to the opinion that such localisation of oxydase as occurs in P. sinensis is at least in large measure a phenomenon of inhibition. We shall see in a later section, that, as postulated by Mendelian.s, flower colour may be inhibited. We know that the result of crossing a dark red- and a reddish-stemmed plant is the production of a reddish F^, and that the F., generation from this cross consists of .3 reddish : 1 dark red-stemmed ; that is, dark red stem behaves as a simple recessive to reddish stem. Nevertheless, as we have just seen, red stem differs from reddish stem in possessing pigment in certain cortical and stelar tissues which are not pigmented in the reddish-stemmed plants. This being so, it would be expected that the presence of pigment would be dominant to the absence and hence that red stem would be dominant to reddish stem. Since the reverse is the case we can scarcely escape the conclusions that reddish stems contain an inhibitor and that this inhibitor is not powerful enough to suppress pigment formation altogether though it suffices to suppress it in certain tissues. It remains to ask whether partial inhibition of pigment formation is to be attributed to inhibition of the action of oxydase on the chromogen or to inhibition of the processes which lead to the formation of chromogen. We are not in a position to answer this question with respect to stem colour though, as we show in the following section, we can answer it 20—2 288 Oxydases and Pigments of Plants with respect to inhibition of pigment formation in the flower (see page 301). Some of the evidence which we possess .as to the nature of the inhibition of pigment formation in the vegetative parts leads us to favour the view that this inhibition applies to the production of chromogen rather than to the activity of oxydase. This evidence is derived from the oxj'dase reaction given by the outermost cortical layer and various tissues of the stele of certain green-stemmed varieties. Instead of no, or at most a weak, reaction, which is to be expected if substances inhibiting oxydase action are present, the tissues just enumerated give a particularly strong oxydase reaction and hence it would appear probable that these cortical and stelar tissues contain an inhibitor which is capable of preventing the production of chromogen. On the other hand the cortical tissues of the petioles of certain green-stemmed varieties give no reaction for oxydase although the corresponding tissues of red-stemmed forms are extraordinarily rich in that substance, and in this instance the failure to give the reaction for oxydase may be due to the inhibition of the latter substance. Whether inhibition be of the nature of the suppression of oxydase activity, as we know it to be in the dominant white Howers of P. sinensis, or whether it consist in the prevention of chromogen production, it follows that negative results with respect to the oxydase content of a given tissue must be accepted with caution : this applies, of course, not only to qualitative results such as those with which we are dealing, but also and with even greater force to those obtained by quantitative estimates of the oxydase content of plant juices. Elaborate methods are in use for this purpose (cf. Buuzel, 1912) but, unless they are asso- ciated with methods for removing any inhibitors which may be present, the results which they yield must be accepted with reserve. To sum up our observations on the distribution of oxydase in the vegetative parts of P. sinensis : We find that the methods described in Section I serve for the faithful mapping out of oxydases in the several tissues of the plant: that this mapping out leads to the conclusion, that although oxydase is more widely distributed than chromogen, the distri- bution is in conformity with that required by the oxydase-chromogen hypothesis and that, owing to the existence of inhibiting substances, caution must be exercised in interpreting the negative results obtained by the use of oxydase reagents as proof of the absence of oxydases. F. Kbeble and E. F. Armstrong 289 B. The Oxydases of the Flower of P. sinensis. (1) Self Coloured Varieties. The oxydases of the vegetative parts of Primula sinensis are located in two groups of tissues ; one group — the epidermal — is superficial, the other — the stelar — is deep seated. The " epidermal " oxydase is con- fined to the epidermis in certain green-stemmed varieties but extends to the sub-epidermal layer in reddish-stemmed varieties and reaches its vi^idest distribution in the dark red-stemmed races in the peduncles of which oxydase occurs not only in the epidermis but also in the two or three outer layers of the cortex. Hence it follows that the epidermal oxydase is separated widely by the intervening cortical cells from the bundle oxydase. The epidermal and bundle oxydases of the vegetative members have their counterparts in the flower ; but, inasmuch as the cortical tissues of the corolla consist only of some two layers of flattish cells, the epidermal and bundle oxydases of the petals lie in close proximity with one another. Nevertheless, and in spite of their proximity, it is possible to demonstrate macroscopically the presence of both oxydases in the petals. The discrimination between the two oxydases is aided by the fact that they do not react in precisely the same way to our reagents — ■ a-naphthol and benzidine. The former reacts much more quickly and in most cases exclusively with the bundle oxydase to produce a lavender blue colour which picks out the veins in exquisite detail and for the most part leaves the epidermal oxydase unaffected. The selective action of benzidine is less precise. This reagent reacts with the epidermal oxydase to produce a rich brown colouration of the superficial layer of the petals and also produces a similar though darker colouration in the veins. Examples of the colour reactions which are obtained by the use of these reagents are given in Figs. 2, 4, 5, 11, 12, 14, Plate XIX. The coloured (blue) flower shown in Fig. 1 yields with benzidine the reaction illustrated in Fig. 2. Recessive whites give a precisely similar reaction (see Fig. 5) with this reagent. Unlike benzidine, which reacts with epidermal and bundle oxydase, a-naphthol reacts with the latter only both in the case of coloured and of recessive white flowers. Hence as shown in Fig. 4 the veins stand out prominently on an almost unstained ground. The central part of the corolla of these varieties is characterised, as are many other varieties of P. sinensis, by a yellow eye, the colour of which 290 Oxydases and Pigments of Plants is due, not to authocyan, but to plastid pigments ; and it is a note- worthy and general fact that the region of the yellow eye shows no oxydase reaction except in the epidermal hairs which give with benzidine a deep brown-black colouration. The failure of the oxydases of this region of the eye to react with a-naphthol or benzidine is to be attributed to the inhibition of oxydase by the chloroplasts. We have investigated the oxydase contents of the corollas of many other colour varieties of P. sinensis, e.g. Crimson King, Coral Pink and Giant Red among the reds ; various magentas and lavenders, e.g. Giant Lavender; and Czar, Cambridge Blue, etc. among the blues, and though the extent of the reactinn of epidermal and of bundle oxydases varies considerably in the several varieties it is characteristic of them all. Of white-flowered varieties of P. sinensis, genetical research has shown that there are two kinds, which are known respectively as Recessive Whites and Dormant Whites. (2) Recessive White Varieties. The Recessive Whites show by their behaviour when crossed with coloured varieties that they lack a factor for colour. When crossed with a coloured variety they yield a coloured F^ which on self-fertilization gives rise to an F^ generation composed of 3 coloured : 1 white. The usual and evidently proper interpretation of this result is that recessive whites lack a factor for colour which is possessed by the pig- mented varieties. The cross is therefore to be represented thus: c X C F, = Cc i^,= 3C:lc = 3 coloured : 1 white. As we should expect from our study of the oxydases of the vegetative members of P. sinensis that which is lacking from recessive white flowers is not the oxydase forming factor but the factor for chromogen produc- tion. Treatment of the petals with benzidine demonstrates that this expectation is correct, for, as indicated already, the result of the treat- ment is a well marked oxydase reaction in both epidermis and veins (Plate XIX, Fig. -5). Whence we conclude that since the corollas of recessive whites contain both epidermal and bundle oxydases their lack of colour is due to the absence of the factor for chromogen pro- duction. Of all the varieties the flowers of which we have examined only those belonging to three categories show any departure from the F. Kbeble and E. F. Armstrong 291 general rule that epidermal and bundle oxydases are present in the corollas. These three categories are the dominant white, blue with white inhibitory patches and the flaked varieties. (3) Flaked {Ever-sporting) Varieties. We will deal first with the flaked varieties. Snow King and Mt. Blanc Star, the varieties of P. sinensis which we have investigated, bear white flowers marked more or less prominently by splashes of magenta. Sometimes a whole petal is magenta coloured and sometimes a magenta flower appears among neighbouring magenta flaked flowers. Although the amount of flaking varies very considerably the races breed wellnigh true to this habit. Thus Mt. Blanc Star produces offspring the great majority of which are flaked ; but it throws occasionally a plant all the flowers of which are magenta coloured. These magenta flowered plants may bear darker flakes of magenta on a lighter coloured ground and the numbers in which they appear are said to be about two per cent. The genetics of these flaked forms which is in course of investigation by one of the present writers (see Keeble, 1910 A) need not concern us here except in so far that it provides evidence of the exist- ence in the petals of a partial inhibitor of pigment formation. Magenta-flaked white flowers of Mt. Blanc Star give much fainter and far less regular oxydase reactions than are exhibited by any coloured or recessive white varieties. They provide also a good illustration of the relation between oxydase and pigmentation. For, as is exemplified in the text-figure (Fig. 1), if, before treating the flower with the oxydase reagent, the pigmented areas are recorded it is found that the distribution of oxydase coincides very closely with that of the pigment. In the case depicted in the text-figure a flower was chosen which had, in addition to certain irregular magenta flakes, one petal of a uniform magenta colour. A comparison of the distribution of pigment with that of the oxydase shows that the magenta petal gave a well marked oxydase reaction, that the magenta patches on other petals were also the seat of a fair amount of oxydase and that the white areas gave no reaction. The absence of oxydase-reaction from the unpigmented parts of the flower is noteworthy because it is the first piece of evidence which we have been able to produce to show that failure to form pigment may be connected with failure to yield the reaction for oxydase. Flowers of this kind, characterised by a considerable degree of fluctua- tion of colour and by the localisation of such colour as they may have 29-2 Oxydases and Pigments of Plants in flakes or spots, are very common among cultivated plants, for example. Azaleas, Sweet Williams, Stocks and Carnations. They are known as evei'-sporting and their genetieal behaviour is difficult of interpretation. The observations of which we have just given a brief account indicate quite definitely that in the case of the white magenta-flaked flowers of Mt. Blanc Star the ever-sporting habit is associated with irregularities in amount or activity of oxydase in the tissues of the petals. Fig. 1. The coincidence of peroxydase with pigment in the white magenta- flaked flower of Mt. Blanc Star. Diagrammatic. The distribution of pigment in the several petals was recorded with reference to the incision indicated at J) («). Petal A was uniformly magenta coloured, B and C indicate the position of magenta flakes. The peroxydase distribution is shown in fig. 6. The copious wound peroxydase is indicated by the black patch, the position of which coincides with D which marks the place of the wound. (See text and Text-figure 5.) Inasmuch as the problems presented by ever-sporting varieties are of considerable interest, we have extended our inquiry with respect to them to other species of plants. We were the more anxious to do so because, except for the difiicult case of white magenta flaked varieties, in which, as we have seen, the amount of oxydase-reaction is small, we had discovered no race of P. sinensis the flowers of which lack oxydase. Now as pointed out already, this fact, though it might be predicated from our knowledge of the genetics of P. sinensis, is less likely to obtain with respect to certain other plants. Thus, the genetieal behaviour of Sweet Peas is such that two distinct factors for colour must be assumed if this behaviour is to be accounted for in terms of Mendelian hypothesis. Hence the suggestion is bound to present itself that the two factors in question are an oxydase-producing and a chromogen-liberating factor. We have therefore an added reason in seeking among plants other than P. sinensis, for an example of a flower which lacks oxydase. F. Keeble and E. F. Armstrong 293 C. TJie Oxydases of Dianthus harhatus (Sweet William). (1) Ever-sporting Varieties. The nearest approach to a flower of this description which we have found so far is that of the Sweet William {Dianthus harbatus). This species presents a wide range of variety of flower colour. Pure white- flowered races as well as races with purple, red and salmon colour are to be found in almost every garden. In addition to races with pure white flowers, others occur in which the flower is white except for a ring of fiae pink dots or lines across the middle of the petals. Ever-sporting varieties are likewise common. They bear on one and the same inflor- escence flowers of very different colours. Thus in the race with which we have experimented the colours of the flowers of a single plant were deep magenta, strawberry, pale and streaked pink on a white ground and white. In some of the white flowers a small amount of rose coloured pigment occurs a little below the middle of the limb of each petal, and in others the amount of pink colouration is so small that the flowers are almost pure white. If this series of differently coloured flowers of an ever-sporting variety of Sweet Williams be examined for oxydase it is discovered that the amounts of oxydase present in the petals of the several members of the series are strictly proportional to the amounts of pigment in those members. As illustrated in Text-figure 2, all the coloured forms contain both Fig. 2. The oxydase (benzidine) reactions of the flowers of an ever-sporting variety of Dianthus harbatus (Sweet William), illustrating the parallelism between pigmentation and oxydase content. Flower-colour : A. Deep red magenta. B. Light red magenta (strawbeiTy colour). C. Pale rose, blotched. D. White with trace of rose in centre. [The limbs of the petals contain no pigment and no oxydase.] 294 Oxydases mid Pigments of Plants epidermal and bundle oxydases; the most deeply coloured flowers contain most, those of intermediate tint, less, and those which approach most nearly to whiteness, contain the least amount of oxydase. The coincidence of oxydase with pigment in the all but white forms of flower is most impressive. In such forms the pigment is confined to three short rosy lines at the base of the limb of each petal and it is only along these lines, which mark the position of the main veins, that oxydase is found. These approximately wliite forms give but a light brown reaction with benzidine ; the pink pigmented forms give a rich brown and the fully pigmented forms give a brown-black reaction. Hence we conclude that in this example of an ever-sporting flower the extent and depth of pigmentation are determined by the quantitative distribution of oxydase. (2) White Varieties of Sweet William. Among the various, non-sporting varieties of Sweet Williams which we have examined are races with fully coloured, white and nearly white flowers. The fully coloured varieties all give pronounced oxydase reactions; the white and approximately white varieties behave to our reagents in one of two ways. The pure white race gives a very definite, albeit limited, oxydase reaction which is most pronounced in the central region towards the base of the petal limb. This variety is therefore colourless because it lacks chromogen. The all but white race, the petals of which bear a ring of rosy dots or lines about one-third of the way from the point of junction of limb and claw, contains no oxydase except in the region which in the fresh flower is occupied by the rosy ring. Hence this variety, unless indeed it prove to be a dominant white, owes its whiteness to lack of oxydase. The final establishment of these conclusions must await the results of breeding-experiments which are being carried out. Should these experiments lead to the production of a coloured Fi generation, we shall have the proof of the hypothesis suggested first by Miss Wheldale, that, where two colour factors are involved in the production of pigment, one is a chromogen producing factor and the other an oxydase producing factor. But apart from these experiments we have in the cases of white, magenta flaked P. sinensis and of the various races of Sweet William clear evidence that pigment formation depends on oxydase action, that depth of colour is determined by amount of oxydase and that a lack of this substance results in an absence of pigmentation. F. Keeble and E. F. Armstrong 295 D. The Oxydases of Geranium sanguineum. We may cite further evidence in favour of the major proposition that the two factors for pigment formation are chromogen and oxydase. As has been shown by genetical research, with such plants as Sweet Peas (Bateson, 1906) and Orchids (Hurst, 1909), so we show by means of chemical methods that albino races are of two kinds. The white flowered races of Sweet Peas (Lathyi-us odoratus) and of culinary peas {Pisum sativum), so far as we have examined them, all contain ox}'dase of the type present in the coloured forms and hence the lack of colour in these races of the two species is due to lack of chromogen. With respect to the former species, however, it should be remarked that we have not yet had an opportunity of investigating thoroughly the two types of white flowered plants which yield when crossed with one another a coloured Fi. So far as our observations go at present we have found, neither in round-pollened nor in long-pollened albino Sweet Peas, no flower from which oxydase is absent. It maybe that further search will discover such flowers or it may of course be that the factors determining pigmentation are other than those suggested above. In any case the evidence provided by the albino of another species of plants. Geranium sangidneum, is favourable to our hypothesis. The petals of the flower of the purple type of G. sanguineum give with benzidine a definite epidermal oxydase reaction and a yet more marked reaction for bundle oxydase. The pure white petals of the albino variety give with the same reagent a distinct bundle reaction, but no epidermal reaction. Hence this white form is either a dominant white or a true albino of the second type, namely one which owes its whiteness to deficiency of oxydase in the epidermal cells. Although we have been unable, owing to lack of material, to determine absolutely to which of these categories it belongs, the fact that the bundles give a definite oxydase reaction appears to indicate that the white G. sanguineum is not a dominant white. The intermediate form, Geranium lancastriense, which is characterised by a flower of pale flesh colour with darker pink veins stands midway between the type and the albino ; for although it gives no or at most a very slight oxydase reaction in the epidermis of the flower, it gives a very distinct (violet-brown) bundle reaction. It would appear therefore from the observations on ever-sporting races Primida sinensis and Dianthus barbatus and on the albino forms of Sweet Peas and of Geranium sanguineum that two types of albino 296 Oxydases and Pic/nwuts of Plants exist. In the one type the white flowers are rich in oxydase and from the other, as judged by the reactions with benzidine and a-naphthol, oxydase is absent. We hope by the application of these methods to the flowers of the many albinos which occur in cultivation and in the wild state to ascertain whether one or the other t^'pe is of more frequent occurrence in nature. E. The Localisation of Oxydases in the Tissues of the Flower {Primula sinensis). We return now to Primula sinensis. In order to complete our survey of the oxydases of the flower, and before proceeding to discuss the oxydase content of dominant white flowers, we will describe briefly the localisation of the oxydases present in coloured and recessive white forms. The distribution of the epidermal oxydase in the petals is definitely circumscribed. The epidermal oxydase is confined to the epi- dermal cells and the hairs which are outgi'owths from these cells. The distribution of the bundle oxytlase is less sharply defined. By treat- ing tangential sections of the petals with the reagent, oxydase may be seen to follow the veins throughout their whole cour.se and to extend to their finest ramifications. If a section which exposes one of the finer veins be treated with benzidine and then examined micro- scopically the brown granular or needle-like products of the interaction of the reagent and the oxydase are seen as dense masses in the elongated cells of the bundle sheath — which cells are more deeply stained than any others. These elongated cells are wrapped around and also extend beyond the tracheids of the veins. They give off short branches which make contact with corresponding branches of the stellate parenchyma of which the body of the petal is composed (see Text-figure 3). In petals rich in oxydase the stellate parenchyma cells, the branches of which abut on those of the bundle sheath cells, also give oxydase reactions, sometimes as marked but generally less marked than those of the cells of the bundle sheath. The reaction in the cells of the stellate parenchyma becomes more faint as the cells of that tissue are traced further from the veins (see Text-figure 3). The appearance presented by the stellate parenchyma and the bundle sheath is as though oxydase were passing from the cells of the latter to those of the former. We have given reason in a former communication (Keeble and Armstrong, 1912 b) for our belief that oxydase may be translated from cell to cell, and have offered the suggestion that the frequency with F. Kbbblb and E. F. Armstrong 297 which lines of colour are seen to demark the veins of petals is attributable to the action of oxydases which pass from the bundle to the epidermis. Fig. 3. The oxydase content of tlie cells of the bundle sheath of the terminal portions of a vein in a petal of P. sinensis. b.s. Bundle sheath — rich in oxydase. s.p. Stellate parenchyma, the cells in contact with those of the bundle sheath are rich in oxydase : those more distant contain less. ()•- Tracheid. i.c.s. Intercellular spaces. If preparations of sections treated with the benzidine reagent are examined microscopically, the localisation of the brown product of oxydase action may be seen in the cytoplasm of the tissues rich in 298 Oxydases and Pigments of Plants oxydase. It happens very frequently that the walls of these cells take on also a brown stain. Although this staining of the wall may be due to diffusion of the oxidized benzidine derivative from the cell, yet the possibility is not precluded that in the living plant oxydase may occur in the walls of the cells. We are not in a position to make a positive statement on this subject but may point out that changes, often of a remarkable nature, go on in cell walls and in some cases, for example, in the macrospores of species of Selaginella very considerable changes of structure and dimensions occur in cell walls which are far removed from contact with cytoplasm. Therefore it would seem not unreasonable to suppose that oxydases may play a part in the growth processes of cell walls, and that the occurrence of wall staining after the treatment of a tissue with an oxydase reagent may be due to the formation in situ of the colour substance indicative of oxydase and not to the passage of that substance from the cytoplasm to the wall. F. Dominant White Varieties. We have now to consider the oxydase content of those varieties of P. sinensis known to students of Genetics as Dominant Whites. As the term implies, Dominant Whites present the appearance of albinism but, as it also suggests, the albino-like appearance masks a distinct and remarkable genetical constitution. Hitherto the only test serving to discriminate between Recessive and Dominant Whites has been the breeding test. Recessive Whites crossed with coloured varieties give a coloured F^ generation ; Dominant Whites when mated with similar coloured varieties yield a white F^ generation. The F^ plants from the cross, recessive white x colour, give on self-fertilization or on inter- breeding an F„ consisting of 3 coloured : 1 white. The F^ generation derived from self-fertilized or inter-bred F-^ plants from a cross between coloured and dominant white consists of 3 white : 1 coloured. The phenomenon of dominant whiteness does not appear to be very common among plants. It is exemplified by the flowers of Primula sinensis (Bateson, 1906), and the Foxglove (Digitalis purpureus, Keeble, 1910 b). Among animals a similar phenomenon occurs with respect to coat colour in certain breeds of fowls, for example White Leghorns (Bateson, 1906). The interpretation which meets the facts of the genetical behaviour of Dominant Whites is well known and involves the existence of a factor which, even though the factor or factors for colour be present, prevents the development of pigment. In other F. Keeble and E. F. Armstrong 299 words the genetical hypothesis of the nature of dominant whites holds that the latter are due to the inhibition of pigment formation. This Mendelian interpretation is so convincing that it scarcely needs the collateral support to be derived from chemical investigation ; but, although this be the case, it is at once evident that the hypothesis suggests a promising line of inquiry into the physiology of pigmentation. Investigations on this subject made by Miss Wheldale (1910) supply confirmation of the hypothesis by indicating that an inhibitor of pigment formation exists in flowers the pale shades of which are dominant to deeper shades. A further advance has been made by Gortner {loc. cit. 1911) who has produced experimental evidence confirming the conclusion reached by previous investigators, that the black pigment (melanin) of various insects and other animals is produced by the interaction of the oxydase, tyrosinase with a chromogen, tyrosin, and has shown that, when these substances are allowed to act in vitro, the addition of certain dihydroxy phenols such as phloroglucinol, orcinol and resorcinol prevents the reaction from taking place. These substances which exercise an in- hibitory action on pigment formation Gortner terms antioxydases. He suggests further that the inhibition of melanin formation in animals may be due to a chemical change in the chromogen (tyrosin). Gortner's views may be expressed schematically thus : Let r=Tyi-osin, and T"^^ = Tyrosinase. Then 2'+ yos^rn Melanin, and T + derivative oi T + T"'" = Inhibition (Dominant White). We proceed now to consider dominant white flowers of P. sinensis with respect to their behaviour with oxydase reagents. The addition of a-naphthol or benzidine and the subsequent addition of hydrogen- peroxide to intact corollas of dominant white plants results in no oxydase reaction whatever. Even after prolonged action of the reagents both epidermis and veins fail to give the colouration characteristic of oxydase. It follows therefore that either oxydase is absent from the flower or it is inhibited from oxidizing the reagents. It so happens that among the Primulas which one of us has been breeding at Reading is a strain derived from a cross between a pure blue-flowered variety and the white, magenta-flaked Snow King to which reference has been made already. Among the descendants of this cross are certain plants illustrated in Plate XIX, Figs. 10 and 13, the flowers of which are 300 Oxydases and Pigments of Plants characterised by fairly regular and symmetrically placed white areas on an otherwise uniformly blue ground. We have ground for believing, both on account of the origin and of the genetical behaviour of these plants, that the white areas represent what may be called inhibitory patches. It is further to be mentioned that these white-zoned blue flowers exist in two forms. In the one form, all the flowers of the plant are marked symmetrically with the white areas and remain in this state as long as they last. In the other form, certain of the flowers and par- ticularly those which are produced late in the season show a blurred, pale blue colour extending from the blue perimeter into the white areas. The plants which exhibit the white areas sharply and per- manently are homozygous, that is breed true to the character ; those in which the areas tend to be blurred are heterozygous for the character ; that is to say, they throw plants which bear uniformly blue flowers as well as others with blotched blue flowers. The results of an investigation of the distribution of oxydase in the corolla of the true breeding, white-zoned blue flowers are depicted in Plate XIX, Figs. 11 and 12, and show in most striking and definite manner that whereas both the epidermis and vascular bundles of the blue areas give well marked oxydase reactions, no such reactions are given by the white areas. Careful observation of the preparations indicates (see Figs. 11 and 12, Plate XIX) that, although they exhibit no sign of epidermal reaction, a faint bundle reaction may be traced in some cases along the veins of the white areas. From the eye of the corolla to the edge of each white patch, the bundle reaction is very distinct ; but as soon as the bundle enters the white area the reaction becomes either imperceptible or at most very faint ; and when the veins pass from the white area into the blue region of the petals, the bundle reaction resumes its distinctness. A comparison of Figs. 11 and 12, Plate XIX with the illustration (Fig. 2, Plate XIX) of the oxydases of a uniformly coloured blue flower shows how remarkable is the definition of the white areas of the blue, white-patched petals. The curious attenuation of the bundle oxyda.se reaction over the white area recalls that which occurs over the yellow eye of the flowers of P. sinensis. Dominant whites and the white areas of the white-zoned blue flowers are alike in that they yield no oxydase reactions, and they stand in this respect in marked contrast with Recessive whites which as we have shown give pronounced oxydase reactions. Recessive whites F. Kbeble and E. F. Armstrong 301 contain oxydase but lack chromogen. Dominant whites would appear from our biochemical investigation to lack oxydase. Such a conclusion however is not compatible with the known results of crossing Dominant and Recessive whites, and we are driven therefore to seek the interpre- tation of the behaviour of the dominant white i-aces in terms of inhibition of oxydase action. It seemed possible that — if inhibition occur — the suppression of oxydase reaction over the white areas might be due to the presence of sugar ; but the application of appropriate tests indicates that reducing sugars are present very generally in the petals of those varieties, coloured and recessive whites, which give good oxydase reactions. We conclude therefore that inhibition is not due to the presence of reducing sugars. Those (heterozygous) plants in which the white areas are ill defined, show the same readiness to give a colour reaction with benzidine or «-naphthol as to develop a blue colouration when in the living state: cf Figs. 13 and 14, Plate XIX. Just as the blue ground colour of the petal may spread into the inhibitory area in the heterozygous plants, so the benzidine reaction may extend over the boundary be- tween the blue, where it is well marked, and the white from which, at first, it is absent. Here again the suggestion of inhibition forces itself on the observer ; for the phenomena are paralleled by those exhibited by heterozygous dominant whites. For whereas pure bred dominant whites have pure white flowers, plants which are heterozygous for the inhibition factor may show a faint tinge or flush of colour over the surface of their petals. The results obtained by the investigation of the oxydase contents in dominant white and white-zoned blue flowers, though they suggest the presence of an inhibitor of pigment formation do not, of course, supply actual proof thereof, nor do they indicate the mode of action of the supposititious inhibitor. If the inhibitory substance exist, it should be possible either to remove or destroy it. If we assume the existence of an inhibitor of pigment formation, then we must suppose that it acts in one of two ways. It either inhibits chromogen formation or it checks the action of oxydase. The evidence which we have just produced points to the latter mode of action, for dominant white and the white- zoned blue flowers are unique among varieties of P. sinensis in not giving an oxydase reaction. We will assume therefore that the inhi- bitor exercises its influence on oxydase. That influence maybe brought to bear in one of two ways : either the oxydase may be destroyed or it may be prevented from doing the work of pigment formation. If the Journ. of Gen. ii 21 302 Oxydases and Pigments of Plants oxydase be destroyed, the only method by which inhibition may be demonstrated must consist in the isolation of the inhibitor, and the addition to it of oxydase. If the latter be destroyed, the evidence for inhibition is forthcoming. If, on the other hand, the inhibitor does not destroy, but only checks the action of oxydase, it should, perhaps, be possible to discover a reagent which, whilst acting destructively on the inhibitor, leaves the oxydase unharmed. Could this be done, the addition of the appropriate reagents should demonstrate the existence of oxydase in the dominant white flower. We have pursued our inquiry along the lines suggested by these reflections and have succeeded in demonstrating experimentally the existence of an inhibitor of oxydase in the flowers of Dominant whites. As the result of experimenting with various substances, we have found that dominant white flowers, after preliminary treatment with certain reagents, are no longer refractory to benzidine or a-iiaphthol, but give with them well marked reactions for epidermal and bundle oxydases. The reagent which is most efficient in producing this result is hydrogen cyanide. Thus, if a dominant white flower be treated for 24 hours with an aqueous solution of hydrogen cyanide and then washed with water and treated with the oxydase reagent, it gives a uni- form and marked oxydase reaction. A comparative examination of Figs. 6 and 8, Plate XIX, shows how striking is the difference in behaviour with respect to oxydase reaction between a dominant white flower placed directly in the oxydase reagent and a similar flower treated previously with hydrogen cyanide. Whereas the former shows scarcely a sign of oxydase, the latter proves itself by the reaction to be rich in that substance. The most satisfactory results are obtained when the following method is practised : Immersion of the dominant white flower in a 0'4 per cent, solution of hydrogen cyanide for 24 hours, washing with water, addition of benzidine (alcoholic solution), washing and then adding to the water a drop of hydrogen peroxide. Instead of hydrogen cyanide, a saturated solution of carbon dioxide may be employed, but the removal or the destruction of the inhibitor takes place more gradually with this reagent than with hydrogen cyanide (see Fig. 7, Plate XIX). Our white-zoned blue flowers provide us with material for verifying the conclusion that hydrogen cyanide brings about the removal or destruction of the inhibitor. If a blue flower with inhibitory patches be treated with hydrogen cyanide in the manner described above. F. Keeble and E. F. Armstrong 303 the subsequent addition of the oxydase reagent brings about a uniform colouration of the petals. The originally white areas are now as deeply stained as the blue regions, and the veins in the former, which as we have seen yielded at most a faint oxydase reaction give after this treat- ment as marked a reaction as those in the blue areas of the flower. The results confirm the Memlelian hypothesis that dominant white flowers owe their lack of pigment to the j)''csence of an inhibitor of pigment formation. They show moreover that the inhibition is exercised, not on the process which results in the liberation of chromogen, but on the oxydase and that the inhibitor acts not b}' destroying oxydase but by effective interference with its action. Attention may be drawn to the fact that, as shown by the results obtained with dominant white flowers and contrary to the general opinion, hydrogen cyanide does not destroy oxydase. We may summarise our observations on the oxydases of the flower (sections B — F) thus : In all coloured and recessive white varieties of P. sinensis oxydase is present in the petals. It occurs in two situations, namely in the epidermis and in the bundle sheath of the veins. The epidermal and bundle oxydases react differently with our reagents (a-naphthol and benzidine). Dominant white varieties of P. sinensis contain an inhibitor of oxydase. On the removal of the inhibitor from the petals of dominant white flowers a strong oxydase reaction is obtained. The white areas in the petals of certain races of blue-flowered Primulas also contain an inhibitor which prevents the oxydase contained in those areas from reacting with oxydase reagents. When this inhibitor is removed the white areas give well marked oxydase reactions. Ever-sporting varieties of P. sinensis and of Dianthus barbatus show most epidermal oxydase in the most deeply pigmented flowers, less in the less pigmented and none in the white flowers. The albino forms of P. sinensis, Pisum sativum, Lathyrus odoratus (in the forms as yet examined) all contain oxydase and their floral albinism is attributable to lack of chromogen. The white-flowered Geranium sanguineum lacks oxydase and we are of opinion that it owes its albinism to lack of oxydase. Albino or approximately albino forms of Dianthus barbatus are of two forms ; in one form oxydase is present and from the other it is absent. 304 Oxydases and Pigments of Plants G. TJie Nature of the Oxydases in FloxDers. (1) The Oxydases and Peroxydases of Prmuda sinensis. As indicated in the footnote at the beginning of the section the term oxydase is used iu the foregoing sub-sections (A — F) to include both oxydase and peroxydase, that is to say those oxidising substances which react directly with benzidine or a-naphthol (direct oxydase) and those which react with these reagents only after the addition of hydrogen peroxide (peroxydases). Our reasons for the practice which we have adopted are threefold: first to simplify description; second because a given tissue may yield, in one variety, an oxydase reaction and, in another variety, a peroxydase reaction ; and third because there is evidence that a tissue of a given variety at one time and under one set of circumstances may contain peroxydase, and at another time and under other circumstances may contain a complete oxydase — namely peroxydase plus organic peroxide — and so give a direct reaction. It is necessary therefore to describe the results of our observations on the nature of the oxydase content of the various tissues of P. sinensis and of the other plants which we have investigated. In the case of P. sinensis direct oxydases are relatively rare and peroxydases are the rule. Thus the oxydase reactions of the petals of coloured and recessive white flowers ai'e invariably or all but invariably indirect ; in other words peroxydases are present in the flowers both in the epidermis and in the tissues of the veins : hence we may speak of epidermal peroxydase and bundle peroxydase as present iu the petals of the flower. The only exception to this ride occurred in the case of the flower of a Sirdar, one petal of which gave on one occasion a vvell marked direct oxydase reaction. We have no evidence, except iu the single example just recorded, of the existence of direct oxydase in the flower of P. sinensis. We have satisfied ourselves, however, that it occurs in the vegetative parts of normal plants. Thus sections of flower-peduncles of dark red-stemmed varieties, of green-stemmed Sirdars and of reddish varieties, may all possess direct oxydase in the phloem. In Sirdars and in dark red-stemmed varieties there is evidence that the pericycle contains a direct oxydase. On the other hand it is very rare indeed for the epidermal tissues of plants grown under normal conditions to exhibit a direct oxydase reaction. We have obtained such reactions occasionally in certain red-stemmed varieties; for example sections of flower-peduncles treated with benzidine may give the colouration characteristic of the oxydase reaction in the epidermal cells as well as in the phloem. F. Keeble and E. F. Armstrong 305 For reasons which will be apparent immediately there is no need to attempt to discriminate more closely between the distribution of per- oxydase and that of oxydase in the normal flower. What is evident and of importance is the fact pointed out already by Miss Wheldale and by Clark that peroxydase is more widely distributed than the organic peroxide which activates it. Even in the case of the phloem which, as we have seen, gives a direct reaction there appears to be more per- oxydase present than the organic peroxide is capable of activating ; for the result of adding hydrogen peroxide to sections which have already given a direct reaction, is to increase that reaction. Hence it would appear that the efficiency of the system, peroxydase and organic per- oxide, is determined by the extent to whicli the organic peroxide is present, and that whereas peroxydase is relatively stable, the organic peroxide is unstable. We have satisfied ourselves not only that this is the case but that external conditions play an important part in determining the amount of peroxydase present in the tissues of a plant. (2) The Oxydases and Peroxydases of Other Flowers. Before proceeding to justify this statement we will describe briefly the nature of the oxydases in the various plants to which reference is made in the preceding pages and in certain other species which we have had occasion to examine. Flowers of the Sweet Pea and of the Culinary Pea contain no direct oxydase in their epidermis and either none or a very small amount in the veins. They give, however, well marked peroxydase reactions. Geranium sanguineum possesses direct oxydase both in the epidermis and bundles of the petals. The pale flesh-coloured variety G. lancastriense contains direct oxydase in its veins and peroxydase in its epidermis. The white variety contains in its epidermis neither oxydase nor per- oxydase, but its bundles give a distinct peroxydase reaction. Coloured varieties of Sweet William give good oxydase i-eactions in both bundles and epidermis. Species of Primus and Pyrus are of interest in this connection. Those species the flowers of which are white, and remain white on fading, contain peroxydase only; those species which turn brown on fading contain direct oxydase. The very general phenomenon of browning presented by dried plants is to be regarded in all probability as an indication of the presence of a direct oxydase, and in order to prevent the discolouration of herbarium 21—3 306 Oxydases and Pigments of Plants specimeus some method must be devised whereby the oxydase is destroyed. It is probable that the method of preserving the colours of flowers by drying them in sawdust or sand at moderately high tem- perature owes its efficiency to a destruction of oxydase. (3) Tlie Influence of Ligld and Darkness on the Oxydase Content of Plants. We now turn to the consideration of the influence of external conditions on the oxydase content of plants. From our experiments with P. sinensis it would appear that light and darkness play an all- important part in determining the amount of oxydase present in plant tissues. As demonstrated by the facts which we record below, light exercises a destructive influence on the organic peroxide constituent of oxydase. Thus under normal conditions of illumination a tissue may give no reaction with a-naphthol or benzidine, though it yields a well marked peruxydase reaction when hydrogen peroxide is added. When, however, a plant is maintained in darkness for 24 hours or longer, the tissue corresponding to that previously tested gives a pronounced and direct reaction with the oxydase reagents. In illustration ut' this fact we may cite the following examples : — Sections of the flower-peduncle of a reddish-stemmed plant which had been maintained in normal con- ditions of illumination gave no direct reaction with benzidine. Similar sections from a sister plant, which had been kept in the dark for 48 hours, gave a distinct oxydase reaction in tlie epidermal hairs. Other sections of the same two plants treated with a-naphthol gave the follow- ing i-esults : the illuminated plant — a direct reaction (faint lilac) only in the phloem ; the dark kept plant — a much deeper reaction in the phloem (rose-colour to almost black) and a fair reaction in the epidermis and hairs. The same experiment shows further that the effect of dark- ness is also to increase the peroxydase content of the tissues. Thus, if flowers of sister plants, one exposed to normal illumination and the other maintained in the dark, be tested for peroxydase the reaction of the latter is found to be so definitely more considerable as to be appreciated by macroscopic examination. Text-figure 4 is typical of the results which were obtained in numerous experiments. Whatever be the interpretation of these facts the phenomena them- selves are definite. Darkness leads to the formation of peroxide and to an increase of peroxydase. We cannot say whether the latter result is to be interpreted as being due to a destructive action of light on oxydase or whether it is to be regarded as a consequence of the F. Keeble and E. F. Armstrong 307 continuous using up of oxydase in the production of new pigment to replace that which, for all we know, may be continuously destroyed when the plant is exposed to light. It is a well known fact that conditions of illumination influence the amount of anthocyan pigment which occurs in a plant. For example, it is a common practice among horticulturists to enclose choice fruits such as grapes and apples in translucent paper bags and it is claimed that this expedient, beside protecting the fruit from insects, improves its colour. This, if true, would point to the con- clusion that light of high intensity exercises a destructive influence on anthocyan pigment. ...ft**. ^, Ai A., B, B., 4 A. 4B. ■ Fig. 4. (From photographs.) The effects of Light and Darknes.s on the Peroxydase of Primula sinensis. Ai and Bi, normally illuminated plants. J.) and B-,, plants kept in darkness for 48 hours. A. A double, light magenta plant (8/2/2/11) : flowers treated with benzidine and hydi-ogen peroxide. B. A white magenta-flaked plant of Mt Blanc Star: flowers treated with a-naphthol and hydrogen peroxide. The most casual observations in the garden show that the depth of colouration of flowers varies considerably during the course of develop- ment of the flower. Thus the petals of many varieties which are white in the mature stage are pink or pinkish in the bud stages and it is po.ssible that we have in such instances an example of the pigment ■destroying action of light. Although an adequate discussion of the facts just recorded would be out of place in the present communication, it will be evident that if they are shown to be true generally these facts may have an important bearing on many phenomena other than those connected with the pig- mentation of plants. For if we ascribe to oxydases a general role in the metabolism of the plant as well as a special function in pigment pro- duction, the fact that the oxydase content of plant tissues waxes in darkness and wanes in the light may have bearings on the phenomena of periodicity which are at once such puzzling and general attributes of the Vegetable Kingdom. The work of Palladin (1911) and others 808 Oxydases and P if/ me ids of Plants indicates that oxydases have such a general function as is postulated above and that they are part of the respiratory mechanism of the plant. Hence it is reasonable to suppose that the rate of respiration of a given cell is determined by the amount of oxydase present in that cell. If light exercise directly or indirectly a destructive action on the oxydase content of the cell the rate of respiration of the latter will fall off during the day and will rise again after a sufficient exposure to dark- ness has set going the oxydase secreting apparatus of the cell and allowed of the accumulation of pei'oxydase and organic peroxide. It may be that, beside the phenomena of periodicity referred to above, the remarkable respiratory phenomena presented by succulent plants are attributable to their diurnal rhythm of oxydase destruction. During the night the respiration of such succulent plants as Mesemhry- anthemum results in a smaller output of carbon dioxide than that which takes place during the day. Instead of the respiratory substances becoming completely oxidised, they produce incompletely oxidised bodies, namely, organic acids. During the day the normal respiration is resumed and the organic acids which have accumulated at night disappear. We propose to investigate this phenomenon in the light of our knowledge of the diurnal variation of oxydase. Lastly a brief reference must be made to the influence of wounding on the liberation of oxydase. As is well known the effect of mutilating a tissue is to produce a speedy and copious liberation of oxydase. The benzidine reagent serves to indicate wound oxydase. That this is so is illustrated in Text-tigure 5, which represents white corollas of A B Fig. 5. (From a photograph.) The wound peroxydase of Primula sinensis. Each of the petals of a dorainaiit white flower of P. sinensis (.5 A) was stabbed in three places with a needle. The wounded corolla and also one from an uninjured flower (5 B) were subjected to the action of the benzidine reagent, then washed with water and treated with hydrogen peroxide. The uuwounded corolla gave no peroxydase reaction : the mutilated corolla gave an intense reaction in the neighbourhood of each wound (see text). F. Keeblb and E. F. Armstrong 309 P. sinensis the surface of one of which was wounded in several places by means of the point of a needle. The flowers were transferred at once to the benzidine reagent and treated subsequently with hydrogen peroxide with the result that the wounded areas gave an intense peroxydase reaction. It is therefore evident that the wound oxydase is in this ease of the nature of peroxydase. Experiments of a similar nature made with other flowers lead to the conclusion that when a peroxydase only is present in the coloured or white parts of the petals the effect of wounding is to bring about copious liberation of peroxydase, but when a direct oxydase is present wounding results in the liberation of direct oxydase. The main ftxcts dealt with in the foregoing section may be sum- marised as follows : Cells in which anthocyan pigment is present contain oxydase in one of two forms, namely peroxydase or complete (direct) oxydase. The latter is found in the Howers of Sweet William {Dianthus barbatus), of Geranium sanguineum and certain species of Pyrus and Prunus. The former, of more general distribution, occurs in P. sinensis, Lathyrus odoratus, Pisuni sativum and many other plants. The oxydase content of a plant varies with external conditions. A tissue of a normally illuminated plant contains less peroxydase than is contained in the corresponding tissue of a plant kept in darkness ; and the organic peroxide constituent of the complete oxydase, though it may be absent from the normal plant, makes its appearance after that plant has been maintained for some time in darkness. The wound oxydases of plants resemble those which are concerned in the work of pigment production. Those plants which contain per- oxydase only, liberate, when lacerated, wound peroxydase and those which contain both peroxydase and organic peroxide show in their wounds the complete oxydase. For summaries of other subsections see pages 288 and 303. In conclusion we wish to express our thanks to Miss D. Richardson for her kindness in preparing the coloured drawings from which the figures of Plate XIX are reproduced ; to Messrs Sutton and Son and to Mr Macdonald, the Primula expert of that firm, for providing us with some of the material used in the course of the experiments, and to Mr G. Coombs, Assistant Lecturer in Botany, University College, Reading, for the drawings represented in Text-figures 1, 2 and 3. 310 Oxydases and Pigments of Plants DESCRIPTION OF PLATE XIX. The illustratious are reproduced frum water-culciiir drawings by Miss D. Richardson from natural flowers (Nos. 1, 3, 10 and 13) and from preparations made by treating the flowers with reagents for oxydases (see text). 1. A uniformly (self) coloured blue flower (natural colour). 2. The same after decolourisation with the benzidine reagent and subseiiuent treatment with hydrogen peroxide ; showing epidermal and bundle peroxydases. 3. A white-flowered form (natural). 4. A recessive white (a-naphthol and H^Oj); showing bundle peroxydase. 5. A recessive white (benzidine and H.jOo); showing epidermal and bundle peroxydases. 6. A dominant white (benzidine and H.jO^). 7. A dominant white (treated first with carbon dioxide, then with benzidine, and sub- sequently with HaO.j). Cf. with 6. 8. A dominant white treated with hydrogen cyanide — benzidine — H.vOj. Cf. with 6. 9. A dominant white treated with HCN, a-naphthol H.^O-). 10. A blue with white inhibitory patches (54/2/1). F^ of cross between Cambridge blue and Snow King (natural colour). 11. The same after decolourisation with the a-naphthol reagent and subsequent treatment with H.,0.2 . 12. Another flower of 54/2/1 after decolourisation with the benzidine reagent and subse- quent treatment with HoOo . 13. A heterozygous plant of the same race (54/2/1) natural colour. 14. The same after decolourisation with the benzidine reagent and subsequent treatment withHaOa. REFERENCES. 1883. Pick, H. "Ueber die Bedeutung des rothen FarbstofTes bei den Phanero- gamen u. die Beziehungen desselben zur Starkewaiidenuig." But. Centbl. 1883, Vol. XVI. 1904. Durham, Florence M. "On the Presence of Tyrosinases in the Skins of some Pigmented Vertebrates — Preliminary Note." Proc. Rot/. Soc. 1904, Vol. Lxxiv. p. 310. 1906. Bateson, W., Miss E. R. Saunders and R. C. Punnett. " Reports to the Evolution Committee, Royal Society, London." Report JII, p. 18. (See also Report I, 1902.) 1908. PalIjADIN, W. " Die Verbreitung der Atmungschromogene bei der Pflanzen." Ber. d. Bot. Oes. 1908, Vol. xxvi. p. 378. 1908. . " Die Bildung der Atmungschromogene in der Pflanzen." Ibid. p. 389. 1909. Hurst, C. C. " Inheritance of Albinism in Orchids." Gard. Chron. 1909, Vol. XLV. p. 81. 1909. Kastle, J. H. " The Oxidases." U. S. Treasury Dept. Hygienic Laboratory. Bidletin, No. 59, Decembei- 1909. JOURNAL OF GEiNETICS. Vol.11. N? 3. PLATE XIX. c?" Vu^ ^ 10 .^f^^:. '^ 12. iS, 13 - 'A'llson . Cambri'Jof .r JOURNAL OF GENETICS A periodical for the publication of records of original research in Heredity, Variation, and allied subjects. Edited by W. BATESON, M.A., F.R.S., Director of the John Innes Horti- cultural Institution, and R. C. PUNNETT, M.A., F.R.S., Professor of Biology in the University of Cambridge. Volume I (1910 — 1911) with 40 plates and numerous text-figures, now ready. Price, in four parts, paper covers, 30s. net, or bound in buckram, 34s. 6d. net. Buckram binding cases can be supplied to subscribers, at 2s. 6d. net. Subscribers' sets can be bound for 4s. 6d. including the case. The Journal of Genetics will be issued in parts as material accumulates, and a volume appearing, so far as possible, annually, will consist of four such parts. The Subscription price for a volume is 30*. net (post free) payable in advance ; separate parts 10s. each, net. LONDON: CAMBRIDGE UNIVERSITY PRESS: FETTER LANE A CONSIDERED OPINION " Some years ago, I happened to be reading the biography of Darwin, and was struck by the frequency with which the great naturalist consulted the GARDENERS' CHRONICLE. I decided that what was good enough for Darwin was good enough for any naturalist, and thus I became a regular reader. No other investment has brought me in so rich a return as that repre- sented by the fifteen shillings which is the price of the annual subscription. Every week the GARDENERS' CHRONICLE teaches me something new, either in the art of growing plants, or in the science of understanding them. The knowledge which I have acquired from a study of its pages has made my garden more attractive to my friends, and a hundredfold more instructive to myself No work on the shelves of my library is consulted more frequently. The introduction of COLORED PLATES— a new feature of the GARDENERS' CHRONICLE— adds considerably to the value of the paper as a record of horticulture, and lends an additional charm to the pages of this oldest and most progressive of horticultural journals." Subscription : 15s. per annum, post free On sale everywhere, 3d. weel q, we get coupling; if q is > p, we have repulsion. But we may have reduplication between A and B of the form p : q : q : p and between A and C of the form r : s : s : r. In this event there will be a derivative reduplication between B and C, the form of which may be ascertained as follows : — The gametic series will be prABC +psABc + qrAbC + qsAhc + qsa.BC + qra.Bc + psabC + pra.bc, and, by extracting, the derivative reduplication is found to be BC : Be : bC : be :: pr + qs : ps + qr : qr + ps : qs + pr, or more simply :: p?' + qs : ps + qr : ps + qr : pr + qs. This is the most general formula for a derivative reduplication and is of course applicable to all the preceding simpler cases. The following diagram illustrates the course of the assumed segre- arations and cell-divisions : — qrAhC qs Abe prABC ps ABc ABCc xp abCc jsaBC fsabC pr ahc raBc 320 Forms of Reduplication These considerations shew that the reduplication hypothesis adequately explains the occurrence of all the ratios hitherto determined. We perceive too how segregation and cell-division may he associated, and that these appear to be carried out symmetrically. In the complete absence of reduplication there is a typical radial symmetry of the segregation apparatus. When reduplication sets in, a bilateral structure is developed, and this may ultimately assume quite a complex form. There seems some reason, moreover, to believe that the development of cells at the two ends of the same axis may be unequal. This would produce a new form of symmetry — -the structure becoming two-ended, enabling one to distinguish not only between different axes, but between the two ends of the same axis. In such a case, with a single pair of allelomorphs A, a, we should get a divergence from the gametic ratio, — 1 : 1 and the normal zygotic ratio, — 1 : 2 : 1. Such divergences are not infrequently met with in the literature of genetics. We may, therefore, ultimately find cases of asymmetrical types of reduplication, such as are represented by the ratios (1) 'W : X : y : 7U, (2) w : X : X : z. (3) w : X : y : z. The experimental determination of such ratios would of course be difficult. Finally let us consider the case of four or more factors A, B, C, D ... with reduplication between A and B, A and C, A and D ... of the form M : 1 : 1 : n, m : \ : \ : in, f : \ : \ : p In addition to the derivative reduplication between B and C, there will be now reduplications also between B and D and C and D .... The gametic series for four factors A, B, C and D would be nmpABCD + nviABCd + npABcD + «ABcd -1- mpAhCD + mAbCd + yjAbcD -1- Abed + aBCD -f- jiSiBCd + w^aBcD -|- w;)aBcd + (iabCD + «pabCd -t- )/?;;abcD + nmpa.bcd and it can be shewn, by extracting, that the reduplications between B and D and C and D have the form : — BD : Bd : bD : bd :: rip + I : n + p : n + p : np + 1, CD : Cd : cD : cd :: mp + I : iii + p : in +p : mp + 1. A. H. Trow 321 This result may be reached more easily by making use of the general formula on p. 319. For if AB : Ab : aB : ab :: n : 1 : 1 : n, and AD : Ad : aD : ad :: p : 1 : 1 : p, then BD : Bd : bD : bd :: np + 1 : n+p -.n+p: np + 1. Any number of derivative ratios may be ascertained in the same way by this method. This more complex case may be represented graphically thus : — «mpABCD m aBcD m^;aBcd nm/j abed According to this scheme of segregation (which however must not be regarded as the only possible one), each additional factor (or pair of allelomorphs) Ee, Ff, Gg, etc. will necessitate a further dichotomy of each branch. If these additional branches are equally developed it can readily be shewn that reduplication does not take place. We have the important rule that equal dichotomies produce normal segregation ; uneipial dichotomies produce reduplications. These two types of behaviour may occur in any order or at any stage in the phylogeny, but as Bateson and Punnett have already stated, they cannot occur simul- taneously. 322 Forms of Beduplieafion There seems to be no reason why the most various types of re- duplication should not occur together in the same plant as the result of the same cross. The hypothesis of reduplication seems adequate to explain the occurrence of any type of ratio. The most suggestive point which emerges from the analysis is the importance of the product nmp ... and of its constituent factors. From these, when all the factors and all the ratios in any one cross have Ijeen ascertained, it should be possible to compute the minimum number of successive cell-divisions needed to produce the complete system of segregation. It ought to be possible to determine also, in sweet-peas for example, the number of successive cell-divisions which normally intervene between the first division of the zygote and the last of the gametogenic divisions, and the distribution of these in the ontogeny. Comparison of the two results might serve to fix the stage at which segregation takes place. It is then advisable to distinguish between primary and secondary reduplications. A ratio of reduplication ascertained by experiment may belong to either series. The gametic series is based upon the primary reduplications alone. Every observed type of reduplication must be assigned to its pi-oper position. It is comparatively easy, as we have seen, to calculate the secondary from the primary reduplications. The schemes on p. 323 will illustrate the relationships of primary and secondary reduplications. It is perhaps advisable to add that systems of segregation will probably be seldom found in which all the primary reduplications take place between one factor A and a number of others B, C, D, E, etc. Primary reduplications may occur between any pair of factors, and the consequent secondary reduplications will undergo corresponding modi- fications. The construction of the gametic series, when the ratios of primary reduplication are known, is easy, and from these any secondary re- duplication is ascertainable. The following scheme illustrates such a system of reduplications : — Primary reduplications Secondary reduplications A and B = ?i : 1 BandC = ;K:l AandC= nm + 1 : n + ?h C and D = p : 1 A and D = hhi/i + ii + iii+p: iim + np + mp + 1 B and D = iitp + 1 : 7n +p A. H. Trow 323 Q) O w -5 T3 > -a H u." tJ d < w ^ + + s. a, »H rH + + >- », M< 11 II u ll. 'O ci oJ Q Q Si. Cji V + + + s S rt rH iH + + + s. &1 !* K II II II o u u. ■a Tl ■n n a a o o o R a. «5i 1^ + + + + S s 8 a rH iH i-H t-t + + ■1- + E '^ &1 ^ II II II II O Q u li. -n r^ -a rrt c c q Oj cd ca m CD CQ CO II II CO o a c < < a, ==^ t» Q llJ LL rs '^ 13 a a a < < < a Q Q + S a. + + + S. g H II II II Q HI LL -3 TJ '-= a a a g C3 c8 o o o + + + + S S S S + + + + §^ s I § II II II II U Q u Li. ^ '^ ^3 t; a a :: a cj cs cs cd CQ CO CQ CQ ft ^ li F li II II CQ (J Q UJ LL -^ -O TJ T! -73 a c c a c cd o3 cS oj ti < < < < < II llJ o o LlJ LL c5 ce t3 (J o o ■13 lO 'M tr- ^ t' CO ■-H rH CO M II II II O Q UJ LL c e3 T3 C c3 T3 CQ CQ CQ CO • • CO -^ IC CO ?7 II II II II II CQ o a LJ LL -rr r— r— r— '-1 Fh S a S a p ed 03 =a o! < < < < < s II LL Q Q Q UJ IL ^3 ns 1:3 3 a c ^ cS ce o o o »c 00 r-< lO ■H< c^ rt r^ II II 11 II o Q LU Ll "2 3 -a a ca r3 13 i CQ CO CQ CD rH Cq CO i-H i-l II II II II II CQ U O LlJ LL 13 ^ ^ 'TS ^ a a c a c c2 o3 c€ cd sS < < < < < 324 Forms of Redvplication It is also noteworthy, that complex reduplications may arise owing to the combination of a primary and a secondary reduplication in the same gametic series ; e.g. the primary reduplications may be of the following types : A and B = « : 1 : 1 : n A and C = »( : 1 : 1 : m, B and C = jO : 1 : 1 : p. The first two alone involve a secondary reduplication between B and C of the type nm + 1 : n + m : n + m : nin + 1 , and this combined with the primary reduplication between B and C gives the complex reduplication for B and C of BC : Be : bC : bc :: p {nm + 1) : n + vi : n + m : p (inn + 1). A careful study of systems of segregation will therefore, as soon as two or more reduplications have been discovered, furnish the student of genetics with data which will enable him on the one hand to test his hypotheses by further experiment, and on the other hand to extend and facilitate his researches. It must be borne in mind however that cell-divisions, if they do really set up the phenomena of reduplication, must themselves depend upon the structure of the protoplasm. It may be that the systems of segregation will prove of some value in the analysis of this structure. University College of Sodth Wales and monmodthshike, cardiff. SOME RECENT WORK ON MUTATION IN MICRO-ORGANISMS. II. Mutations in Bacteria'. By CLIFFORD DOBELL. In the following article I shall try to give a coherent summary of some recent work in bacteriology in so far as it is of interest to the student of genetics. This work is very extensive and scattered through numerous papers dealing with medical or purely bacteriological .matters. It is, moreover, to some extent beyond the reach of the general biologist on account of the phraseology in which it is couched. I shall try, therefore, to present the facts in such a way that they may be seen stripped of irrelevant detail and in language intelligible to the average reader. Accordingly, the facts given in the following pages are to be regarded as a selection from a vast array recorded by many different workers, and not as a complete review of even those works given in the bibliography (p. 349). They represent, rather, certain personally chosen facts arranged in an orderly manner so as to interest workers in genetics. It must be remembered, therefore, that many additional facts — some of them perhaps of fundamental importance — are to be found not only in the works to which reference is made, but also in works which I have not considered^. I should like to point out that I employ the word " mutation " throughout in the sense of Wolf (1909), who follows Baur in this 1 In a previous article (this Journal, Vol. ii. p. 201) I have given some account of recent work on mutation in Trypanosomes. ^ Those desiring an account of the work hitherto done on variation in bacteria, will find it admirably analysed in the recent monograph by Pringsheim (1910). 326 Mutation in, Mirro-Or That is, in those cases in which successful cultures resulted. In many cases, the isolated individuals grew badly or not at all. Journ. of Gen. ii 24 346 Mutation in Micro-Organistns more or less alike. The majority represented merely temporarily modified individuals : only a very few were permanently mutated organisms. There is, of course, nothing to indicate what factors may have been concerned in the production of these forms in the first place. I will end this section by referring to some work which has just been published by Revis (1912). His observations also concern B. colt. A typical strain of this organism was grown in peptone broth to which malachite green had been added'. The effect of this dye was to produce a new race of organisms which differed both structurally and culturally from typical B. coli. When the organisms were grown subsequently at 20° C. on ordinary gelatin or agar, they formed " large viscous, circular masses," consisting of "a mixture of very long fila- ments- and short bacilli, together with a gummy cementing substance." Presumably the race breeds true to these new characters. The organisms were not propagated by the isolation of individuals, but the cultures were very carefully plated out. The purity of the original culture is guaranteed. Revis therefore claims to have produced — by means of malachite green — from a typical B. coli a new race " which is neither physiologically, morphologically, nor culturally a colon bacillus." Further details and confirmation of these observations are to be desired. Concluding Remarks. To epitomize in few words the numerous facts given in the fore- going pages is hardly possible, for what has been written is itself one long epitome of facts and their interpretations. A few general remarks may, however, be permissible to a writer who has travelled thus far over very stony ground. They may serve, moreover, to call attention to certain facts which are undoubtedly important — though the magni- tude of their importance and their significance may well be appraised in very different terms by diffei'ent individuals. It must be understood, ' See also p. 337 supra. - It was already known that organisms o{ the coli-typ}wsns group — and others also — assume a remarkable filamentar form when grown on media containing certain dyes. The first observations in this connexion were made in 1904 by Walker and Murray (British Med. Journ., Vol. ii. p. 16). Similar results have since been obtained by Vay (C. B. Bakt., I. Orig. 55, 1910, p. 193) and others. C. DOBELL 347 then, that the following remarks embody merely my own conclusions drawn from the facts given in the body of this paper and from many other related facts of which no mention has been made. They lay claim to no finality, for the subject is not one upon which any final judgment can yet be passed. If it be assumed that the statements made by various workers, whose observations we have been considering, are correct, then the following conclusions are justifiable. First, it seems established that the Bacteria are subject to mutation — that is to say, in a given race individuals may occur which differ from their fellows in their genetic constitution. Individuals frequently occur which possess new structural or functional features ; and these features, though often the transient peculiarities of the individual only, are in some cases transmitted to the offspring for many successive generations. There is reason to suppose that this phenomenon occurs in nature as well as in laboratory cultures. The progeny of an organism which varies may thus constitute a new race, in which every individual possesses the new character. We might anticipate this, indeed, by consideration of the fact that the Bacteria are non-sexual organisms. For a change in the genetic constitution of the parent — where there is but one — appears likely to find expression in all its offspring. There is no additional complication — in the trans- mission of characters — introduced by a second parent. In sexually- producing organisms, the genetic constitution of two parents must always be considered, and there is not, therefore, such an obviously direct relation between any one parent and its offspring as is seen in non-sexual forms. It seems impossible to gauge the permanency of new races which arise in this fashion. For there are indications that a new race may give rise to other new races or to one indistinguishable from the old race — all races arising in the same way. A race A may produce an abnormal individual, which becomes the ancestor of a new race B. In the same way, the race B may produce abnormal individuals giving rise to races C, D...etc., of which one may be identical with A. There is at present little to indicate the extent to which " reversion " of this sort may occur. The factors which determine changes in genetic constitution are in most cases obscure. It is impossible to say how most mutations have been "caused." In Barber's experiments, the environment was the same for all individuals — or at least he tried to make it so. The factor which determined the appearance of individuals with an altered 24—2 348 Matatioih in Mlcro-Orgavisms genetic constitution can tlierefoie hardly be sought — for the moment — anywhere but in the organisms themselves. In Wolf's experiments, on the other hand, there appears to be evidence that the variations depended in some way upon the environment ; for they occurred most frequently in organisms subjected to the action of poisons. But the relation between the mutation and the chemical is not apparent. The same substance seems to be able to produce two opposite results ; and two different substances seem capable of producing the same result. The remarkable phenomena so well studied by Massini, Burri, and others seem at first sight more illuminating. It appears that certain bacteria, which cannot ferment a certain substance, can acquire the power of fermenting it if kept in contact with it for a sufficient time. At first the organisms cannot avail themselves of the new food around them, but they then undergo a change which enables them to do so. It seems at first sight that the new power is the result of necessity — the " mutation " being a direct and indispensable adaptation to a definite end. But to necessity alone the change can hardly be ascribed — even by a confirmed Aristotelian. For it is apparent (e.g. from the work of Massini) that the ability to attack a certain substance (in this case lactose) is not a necessary condition for the survival of the race. It is, rather, a luxury. The lactose-splitting individuals arise and flourish in a non-lactose-splitting colony ; but the latter can survive for a very long period, and there is nothing to prove that the new race would supplant the old as a result of natural selection. If every individual — as Burri supposes — possesses the power {in posse or in esse) of fermenting the sugar ; and if, under ordinary cultural conditions, only a minority avails itself of this power : then surely it seems absui'd to suppose that the splitting of the sugar is necessary for the survival of the race. These considerations do not affect the fact, however, which seems to be established that there is a direct relation of some sort between the sugar and the change which it produces in the organism. The action of the sugar is specific. Lactose, and lactose alone, makes B. coli mutabile able to ferment lactose, but does not enable it to ferment saccharose or any other sugar. We are not dealing here with a stimulus which may produce one of two opposite reactions, or with a reaction which may be produced by another stimulus. Variations of this sort seem to stand in a class by themselves. Pringsheim (1910) calls them "functional adaptations" or "accom- modations." It has been maintained that all variations in Protista are C. DOBELL 349 really of this sort : but there is little ground for the foundation of such a hypothesis. Many established facts appear to be flatly contradictory. It should not be forgotten, however, that acquired heritable adaptations of this sort are described not only among the Bacteria, but also among the yeasts and other Fungi ; and the observations have been made by many independent and competent workers. These few remarks by no means exhaust the significant inferences to be drawn from the works which have been under consideration. But it is hoped that they may serve to call more attention to certain facts which have hitherto been left in the obscure by-ways of bacteriology. It will be admitted, I think, that the outcome of the work fragmentarily recorded in the foregoing pages will be not merely of interest, but probably of very great importance, to every student of genetics. LITERATURE. 1911. Baerthlein. " Ueber Mutationserscheinuugen bei Bakterien." {Ber, iib. V. Tag. d. fr. Ver. f. Mikrohiol. Dresden, in : C. B. Bait. i. Abt. (Ref.) Vol. L. Beiheft, p. 128.) 1912. . " Untersuchimgen iiber Bad. coli muiabile." (C. B. Bah. i. Abt. (Orig.) Vol. Lxvi. p. 21.) 1912 A. . " Weitere Unter.suchungen iiber Mutationsersoheinungen bei Bakterien." (Ber. iib. d. vi. Tag. d. fr. Ver. f. Mikrobiol. Berlin, in : C. B. Bakt. I. Abt. (Ref.) Vol. i.iv. Beiheft.) 1907. Barber, M. A. " On heredity in certain micro-organisms." {Kansas Univ. Soi. Bull. Vol. IV. No. 3, p. 1.) 1909. Beneoke, W. Review of the work of R. Miiller, published in S. B. physiol. Ver. Kiel, 1909 : and in " Die Umschau," 1909. {Zeitsch. f. iiidukt. Abstam- mungs- u. Vererbungslehre, Vol. ii. p. 215.) 1912. Bernhardt, G. and Makkoff, W. N. "Ueber Modifikationen bei Bak- terien." (C. B. Bakt. I. Abt. (Orig.) Vol. Lxv. p. 1.) 1908. Bdrk, a. " Mutation bei einem der Koligruppe verwandten Bakterium." {ArcLf. Hyg. Vol. lxv. p. 23.5.) 1910. Bdrri, R. " Ueber scheinbar plotzliche Neuerwerbung eines bestimmten Ganmgsvermogens durch Bakterien der Coligruppe." (C B. Bakt. ii. Abt. Vol. XXVIII. p. 321.) 1910. and Andrejew, P. " Vergleichende Untersuchung einiger Coli und Paratyphusstamme." (C. B. Bakt. I. Abt. (Orig.) Vol. lvi. p. 217.) 1909. and Dijggeli. " Beitrag zur Systematik der Coli-aerogenes-Gruppe, u. .s. w." (a B. Bakt. I. Abt. (Orig.) Vol. xlix. p. 145.) 350 Mutation in Micro-Orf/anisms 1912. EiSENBERG, P. " Untersuchungen uber die Variabilitiit der Bakterien. I. Uber sporogene und asporogene Rasseii des Milzbrandbacillus." (C. B. Bakt. I. Abt. (Orig.) Vol. Lxiir. p. 305.) 1912 a. . "Untersuchungen iiber die Variabilitiit der Bakterien. II. Uber sogenannte Mntationsvorgange bei Choleravibrioncn." (C. B. Bakt. i. Abt. (Orig.) Vol. Lxvi. p. I.) 1910. Jacobsen, K. a. " Mitteilungen fiber einen variablen Typhu.sstamm {B. ti/phi imitabile), sowie fiber eine eigentiimliche hemmende Wirkung des gewohnlichen Agar, verursacht durch Autoklavierung." (C B. Bakt. i. Abt. (Orig.) Vol. LVi. p. 208.) 1910. KoWALENKO, A. "Studien iiber sogenannte JIutationserscheinungen bei Bakterien unter besonderer Beriicksichtigung der Einzellenkultur." {Zeitschr. f. Hyg. Vol. lxvi. p. 277.) 1912. Mandelbaum, M. "Veher dan Bacterinm jnctatyp/d." {€'. B. Bakt. i. Aht. (Orig.) Vol. LXill. p. 46.) 1907. Massini, R. "Ueber einen in biologischer Beziehung interes.santen Koli- stamm {Bacterium coli mutabile)." {Arch. f. Hi/g. Vol. LXI. p. 250.) 1909. MiiLLER, R. See Benecke (1909). 1911. . "Mutationen bei Typhus und Ruhrbakterien." {C. B. Bakt. i. Aht. (Orig.) Vol. Lviii. p. 97.) 1910. Pringsheim, H. " Die Variabilitiit niederer Organismen." Berlin. 1911. Revis, G. "Note on the artificial production of a permanently atypical B. coli." {€'. B. Bakt. ii. Abt. Vol. xxxi. p. 1.) 1912. • . " The production of variation in the physiological activity of Bacillus coli by the use of malachite green." {Proc. Roy. Soc. B, Vol. lsxxv. p. 192.) 1909. Sauerbeck, E. " Ueber das Bacterium coli mutabile (Massini) und Coli- Varietiiten iiberhaupt." (C. B. Bakt. i. Abt. (Orig.) Vol. l. p. 572.) 1911. Schroeter and Gutjahr. " Vergleichende Studien der Typhus-coli- Dysenteriebakterien." (C B. Bakt. i. Abt. (Orig.) Vol. Lvm. p. 577.) 1911. Sobernheiji, G. and Seligmann. "Weitere Beitriige zur Biologic der Enteritisbakterien." {Ber. d. v. Tag. d. fr. Ver. f. Mikrobiol. Dresden, in : C. B. Bakt. I. Abt. (Ref) Vol. l. Beiheft, p. 134.) 1912. S0RENSEN, E. "Eine Untersuchungsreihe iiber die Veriinderung einer Urinbakterie in den menschlichen Harnwegen." (C B. Bakt. i. Abt. (Orig.) Vol. Lxii. p. 582.) 1911. Thatsen, a. C. "Studien fiber funktionelle Anpassungen bei Bakterien. (Vorl. Mitteil.)." (C. B. Bakt. i. Abt. (Orig.) Vol. lx. p. 1.) 1907. TwoRT, F. W. " The fermentation of glucosides by bacteria of the Typhoid- coli group and the acquisition of new fermenting powers by Bacillus dysenteriae and other micro-organisms." {Proc. Roy. iSoc. B, Vol. lxxix. p. 329.) 1909. Wolf, F. " Ueber Modifikationen und experimentelle ausgeloste Muta- tionen von Bacillus prodigiosus und anderen Schizophyten." {Zeitsch. ind. Abstammitngslehre, Vol. n. p. 90.) MATERNAL INHERITANCE AND MENDELISM. (FIRST CONTRIBUTION.) By K. TOYAMA. (Zoological Institute, College of Agriculture, Tokyo Imperial University.) (With Plate XX.) CONTENTS. PAGE I. Certain egg-characteristics of the silk-worm 352 II. The origin of those characteristics 353 III. Results of line breeding of certain variants 353 Series 1. The reddish-brown eggs found in the normal divoltine " Shinkawachi " 353 Series 2. The blue-egged variant found in the normal divoltine " Kuni-nishiki " 357 Series 3. The whitish-grey egged variant 360 Series 4. The spindle-shaped eggs found in the normal univol- tine breed 364 IV. Crossing of various breeds or variants possessing different egg- characteristics 367 Series 1. Crossing between Theopldla mandarina and Bombyx mori 367 Series 2. Crossing between normal egged breeds and the whitish- grey egged variant 370 (a) Crossing between tetravoltiue normal egged breeds and the variant 370 (h) Crossing between divoltine cross-bred normal egged breeds and the variant 374 (c) Crossing between divoltine normal egged breeds and the variant 374 Series 3. Crossing between tetravoltine yellow and white . . 376 Series 4. Crossing between various breeds possessing special colour-characteristics of the egg 378 Series 5. Inheritance of the crimson-egged breed .• . . 381 V. General considerations 391 VI. Summary 401 352 Maternal Inheritance and Memlelism In my first contribution to the study of hybridology of insects published in 1906(10), it was shown that certain colour-characteristics of the egg of the Siamese silk-worm follow Mendel's law of heredity. Thanks to the kind suggestion of Prof. Bateson of London, we again undertook a similar series of experiments with various breeds of the silk-worm. Some of the results obtained during the last five years which seem to us to be not without interest to students of heredity will be described in the following pages. I. Certain Egg-characteristics of the Silk-worm. Before going further, we shall first enumerate certain egg-character- istics which are the subject of the present paper. Colour. The ordinary colour of the Japanese silk-worm eggs is a light greenish white when newly laid. With the formation of the blastoderm, the egg gradually assumes a brownish tint which at last turns into brownish slate shaded with some light pink or purple (Figs. 1, 3, 11). There may be found, however, many variants, .some rather deeper, some lighter, and some with different shades. Now and again it happens that some eggs characterized by extraordinary variations of colour are found among normal ones, such as reddish brown (Fig. 2), whitish grey (Fig. 4), blue (Fig. 5), greenish slate (Figs. 6, 10, 12), crimson (Fig. 7), orange, greenish white and many others. Most of the eggs deposited by Japanese green breeds are more or less shaded with green. When newly laid, they are yellowish green and are much deeper in colour than those deposited by ordinary white breeds. Most of the Chinese or European breeds come in a similar category. Shape. The normal shape of the silk-worm eggs is oval, slightly pointed at one end, where a micropyle is situated (see Figs. 1 — 7). It is a little flattened and its surface is convex when newly laid but after a few days it becomes depressed in the middle, thus producing the characteristic form which is familiar to us. In this characteristic, as in the case of the colour, we observed man}' variants, some of them being quite extraordinary, for instance such as spindle-shaped eggs (Fig. l.S) or other irregularly shaped ones, etc. which will be discussed minutely afterwards. K. ToYAMA 353 II. Origin of the Characteristics above enumerated. The egg consists of the shell, vitelline membrane, serosa and yolk, and each of them is coloured or shaded with certain tints or pigments, except the vitelline membrane which mostl}' remains colourless in nearly all breeds. The shell is usually translucent and is slightly tinted with certain colours. In Japanese breeds it is usually white or slightly shaded with brown, flesh-colour, green, or dirty- white or some other tint. That of some Japanese green, Chinese or European breeds is coloured yellowish green or pale green. The colour of the eggs is consequently more or less influenced by the colour of the shell. As to the shape, it is chiefly determined by the characteristics of the shell, which is derived from the epithelium of the oviduct. The cause of the egg-colour is, however, mostly due to the pigments deposited in the serosa which are seen through the shell. The colour of the yolk plays a certain part in the production of the egg-colour only in the case where the formation of the dark pigments in the serosa does not take place, i.e. in newly laid eggs or those oviposited by the spring brood of di-, tetra-, or multivoltine breeds. The object of the present series of experiments is to know what influence, if any, these variants have upon the trend of heredity in their offspring. As to the origin of these variants we are quite ignorant whether they are produced by mutation or by hybrid mutation or some other causes which are yet unknown to us. We only know that they are seldom found among eggs laid by the normal-egged breeds generally reared in Japan. III. Results of Line Breeding of certain Variants. Series 1. The Reddish-Brown Eggs (Figs. 1, 2). In the winter of 1907, Mr K. Ishivata, one of the famous silk- worm breeders in the district of Fukushima in Japan, kindly offered me some normal (Fig. 1) and brown (Fig. 2) egg batches' laid by a divoltine white breed called " Shinkawachi," and said that both of them, even when inbred, gave the antagonistic characteristics in the offspring and thus it was very difiicalt to establish them as constant forms. ' All through this paper, the word "batch " represents the total eggs laid by a moth. 354 Maternal Inheritance and Mendelism As the colour of the shell and yolk of both variants was the same, we must attribute the chief cause of those characteristics to the pigment of the serosa, a product of the combination of both parental gametes. We started our breeding experiments in the spring of 1908. The First Generation. 1908. Spring. We reared two batches of egafs from each variant. The normal series gave 72 matings or batches and the brown series 87, all of which were divoltine white in colour and we were unable to distinguish which were normal and which were brown. This characteristic, producing un- coloured eggs, is one of the normal characteristics of di-, tetra- or multi- voltine breeds in Japan. In these breeds, the egg laid by the spring brood generally produces no dark pigments in the serosa and conse- quently it remains whitish until the embryo is completely developed. Tropical multivoltine breeds, such as Siamese white or yellow which produce 8 or 9 broods in a year, never produce any dark pigment in the serosa, the colour of the egg therefore being determined by that of the yolk and the shell. Sometimes it happens that certain eggs of the spring brood of di- or multivoltine breeds turn into the ordinary dark slate-colour, in which case most or all of them become univoltine in character and do not hatch until next spring comes. On the contrary, all the eggs laid by the summer or autumn broods of divoltine or other multivoltine breeds deposit normal dark pigments in the serosa, thus giving various colours characteristic to the respective breeds. The Second Generation. 1908. Summer. Summer broods derived from the whitish eggs of the spring broods from normal and brown series yielded the antagonistic characteristics as shewn below. 1. Eggs laid hij the Slimmer Broods of the Brown Series. Number of Matings Normal Batclies Brown Batches Mixed Batches Totals No. 15. 11 0 11 7 18 No. 19. 12 10 19 29 58 Totals ... 10 30 36 76 K. TOYAMA Eggs laid by the Summer Broods of the Normal Series Number of Matings Normal Batches BroftTi Batches JUxed Batches Totals No. 18. 12 4 4 4 12 „ 14 2 5 12 19 „ 9 1 1 2 4 No. 4. 1 3 0 0 3 355 Totals ... 10 10 18 38 In the former or brown series, 10 were normal, 80 brown and 7 a mixture of both normal and brown eggs in the same batch, and therefore in this series the normal colour-characteristics remained as recessive. The reverse is the case in the normal series, which produced 10 normals, 10 browns and 18 mixtures, that is to say, the brown is recessive in this series. The Third Generation of Normal Series. ■ In the autumn of 1908, three normal-coloured batches derived from summer broods of the normal series were reared. They gave 58 batches, among which there were 28 normals, 14 browns and 16 mixed batches, that is to say, they again produced the antagonistic character. The third generation of the brown series or brown batches laid by the summer brood in 1908 were reared in the spring of 1909. They gave, as is usual, all divoltine whitish eggs. The Fourth and Further Generations. The fourth generation of the normal series derived from normal eggs laid by the normal series in the autumn of 1908 gave divoltine white eggs, a few being univoltine normals and browns. The same is the case in the fifth generation which was reared in the spring of 1910. In the spring of 1911, i.e. in the sixth generation, we noticed for the first time that this series of normal characteristic inbreeding gave all normal batches with a few divoltine white batches, vifhich may be considered to be normal coloured in character, that is to say, they breed true to parents. On the contrary, the fourth generation of the brown series or summer brood of 1909 yielded, without exception, brown eggs. Since then we have reared them through two generations without producing any antagonistic characteristic. Hence it may be said that this brown form is established as a constant form. Respective figures obtained by this series of experiments are given in Table I. 356 Maternal Inheritance and Mendelism Brown-egged Series. TABLE I. Number of Univoltine Divoltine batches produced batches Number of _ ■•- . lolaX Matings Normal Brown Mixture White batclies 1908 (Spring brood). First generation. 15* 0 0 0 20 19* 0 0 0 61 26 61 Totals 1908 (Summer brood) 19. 12* 15. 11 Totals 0 0 0 87 87 jrood). Second generation. 10 19 29 0 58 0 11 7 0 18 10 30 36 76 1909 (Spring brood). Third generation. 19. 12. 9 ,, 12* .. 25 0 0 0 32 32 0 0 0 35 35 0 0 0 all wbite all wbite Totals 0 67 67 1909 (Summer brood). Fourtli generation. 19. 12. 12. 1* 2 3 4 5* Totals 0 3 0 0 3 0 2 0 0 2 0 18 0 0 18 0 8 0 0 8 0 33 0 0 33 64 64 1910 (Spring brood). Piftb generation. 19. 12. 12. 1. 2» 0 0 0 26 26 5. 8 0 0 0 18 18 Totals 0 0 0 44 44 11)10 (Summer brood) . Sixth generation. 19. 12. 12. 1. 2. 1 0 107 0 0 107 2 0 116 0 0 116 „ „ 3 0 86 0 0 86 4 0 108 0 0 108 5 0 105 0 0 105 6 0 50 0 ■ 0 50 Number of Matings 4* 18* Normal-egged Series. Number of Univoltine batches produced Totals 0 0 0 72 1908 (Summer brood). Second generation. 4. 1 3 0 0 0 18. 9 112 0 18. 12* 6 4 4 0 18- 14 5 5 12 0 Totals 15 10 18 1908 (Autumn brood). Third generation. 18. 12. 5* 0 9 4 0 -, 9* 0 5 8 0 „ 20* 28 0 4 0 Totals 28 14 16 0 1909 (Spring brood). Fourth generation. 18. 12. 5. 17 4 0 0 18 „ 9. 25 0 1 0 10 „ 20. 18* 2 0 0 20 Totals 1 0 48 1910 (Spring brood). Fifth generation. 18. 12. 20. 18. 19* 6 0 0 20 18. 12. 20. 18. 26 0 0 0 13 Totals ... 6 1911 (Spring brood). 18. 12. 20. 18. 19 (5 matings) 25 0 0 33 Sixth generation. 0 0 Totals ... 0 572 0 0 572 * Eggs laid by the mating marked with an asterisk are used as the parents of the next generation. Normal Brown Mixture \Vhite batchf 0 0 0 30 30 0 0 0 42 42 72 3 4 U 43 13 13 32 58 22 11 22 55 26 13 39 29 K. TOYAMA 367 To avoid complication, we give below a graphical summary : B = brown egg batch; ^ = normal-coloured ; ir=divoltLne white; M=mixture of brown and normal-coloured eggs in a batch. Common parent ... N I Parent egg First generation inbred I I W (87) I I N) I W{T2) 1 I Second generation inbred B (30) -I- iV(lO) + i/(36) Third „ „ IK (67) Fourth Fifth Sixth I I i'(lO) + N(15) + M{18) I I 5(14) -f N{2S) + il/(16) B(64) IF (44) B (572) i 1 N {G) + B(1) + WHS) I I N (6) -I- W (33) I I I N (25) + W (4) From the results above obtained, we observe that complete segrega- tion between the two characteristics, the brown and the normal-coloured, took place and that each may be established as a constant form from their common stock. It is much easier, however, to establish the brown as a constant form than the normal. Moreover, we learn that during two or three generations both characteristics even when inbred produce antagonistic characteristics in their offspring, a fact which apparently seems to run counter to Mendelian principles, but which in reality is in perfect accordance with the principles, as will be seen in " General considerations." Series 2. The Blue-egged Variant (Fig. 5). The phenomena of inheritance, similar to those above described, were observed in the inbreeding of the blue variant. This form is a sport from a divoltine normal-egged breed called " Kuni-nishiki," and is characterized by the special blue colour of the egg. In the spring of 1910, only one batch (No. 20) was obtained, through the kindness of Mr S. Saito in Ghifu-Ken. The worms, cocoons, and 358 Maternal Inheritance and 3Ien(Misin moths derived from them were all normal in character. They, inbred, gave 30 batches of eggs, of which, 12 batches were divoltine white, and the remaining 18 all normal-coloured, which suggest to us that all the batches in this generation would be all normal-coloured ones. Three divoltine white batches (Nos. 1*, 3 and 4) which were reared in the summer gave three kinds of eggs, some batches being blue, as in the parental blue, others blue shaded with a brown, which we called " intermediate colour " and the rest normal-coloured batches. There were no batches in which both blue and normal or intermediate forms were found mixed. Respective figures obtained are given below : Number of Matings Number of blue batches produced Number of intermediate batclies Normal- coloured Totals 20. 1* 21 54 68 143 20. 3 12 65 76 153 20. 4 14 46 60 120 Totals 47 165 204 416 Of 416 batches derived from three parent batches, 4-7 were blue, 204 normal-coloured and the remainder intermediate. In the blue- coloured eggs, we distinguished both light and dark-shaded ones. The former we called " light blue " and the latter " dark blue." Five blue batches (Nos. 6, 14*, 24*, 25 and 28) laid by the mating No. 20.1 were reared in the spring of 1911. They oviposited, without any exception, 2.51 batches of eggs, all of them being divoltine white. Eight white divoltine batches were reared in the same summer. Both the light and dark blue series yielded again the antagonistic characteristics as shewn below : Number of Matings Light Blue Dark Blue Normal Totals 20. 1 light blue 14. 3 13 0 8 21 14.15 21 12 15 48 14. 20* 4 4 0 8 Totals 38 16 23 77 20. I dark blue 24. 4 0 0 3 3 24. 9 1 0 0 1 24. 14 2 0 2 4 24.25 0 1 2 3 24. 27 0 0 3 3 Totals 3 1 10 14 Grand totals ... 41 17 33 91 Of the eight parent batches, four gave both blue and normal- coloured batches, two all blue batches and the rest only normal-coloured ones, the total number of batches produced by them being 91. K. TOYAMA 359 In the spring of 1912, six blue batches (three light and three dark blue) derived from the lineage which produced only blue batches were reared separately as in the former generations. They gave the following egg-batches : Number of Matings Number of Univoltine blue batches Number of Divoltine white batches Mixed batches Total number of batches Dark blue series No. 20. 1. 14. 20. 2 0 63 0 6.S >» ») 3 1 18 0 19 >i >> 4* 22 64 1 87 Light blue series No. 20. 1. 14. 20, . 1* 5 91 0 96 )) ») 8 0 52 0 52 iJ ti 10 0 18 0 18 Totals 28 306 335 Of 335 batches derived from the six blue parent batches, 306 were divoltine white as is usual in the divoltine breed, and 28 were univoltine blue coloured and only one was a mixed batch consisting of both divoltine white and univoltine blue-coloured eggs. The summer brood derived from four batches of light blue series and four batches of dark blue series gave the following batches : — Light Blue Series. Number of parent batch Number of dark blue batches laid Number of light blue batches laid No. 20. 1. 14. 20. 4. 4 29 42 5 22 36 >j »» 19 14 16 22 Normal i(?) Totals 71 58 30 9 Totals 71 96 1(?) Dark Blue Series. No. Number of parent batch Number of dark blue batches laid Number of light blue batches laid 20. 1. 14. 20. 1. 1 6 33 ») ») 12 20 45 >» j» 15 25 46 )) a 16 19 49 25 13 31 2(?) 168 Totals 39 65 71 68 46 Totals 83 204 !{■?) 289 Now we are able to extract the blue-egged characteristic as a constant form. As to the light and dark forms, they seemed to be fluctuations of the same character, blue. 360 Maternal Inheritance and Meiidelism Resume : -B = light and dark blue batches ; / = intermediate; W = normal ; ir=divoltine white ; il/ = mixed batch consisting of divoltine white and univoltine blue-coloured eggs. Parent eggs B Eggs of the first generation NCiO) r 1 second generation {i\r (204) +/(165) + i? (47)', I third „ If (251) i I I fourth „ £ (9) I B (49) + N (27) | N (6) I r L n I I fifth „ {B(28) + If (306)} I sixth „ all B (445) Series 8. The Whitish-Greij egged Variant (Fig. 4). This variant from the normal egged breed is characterized by the peculiar structure of the .shell. As is well known, the shell of normal breeds is elastic and translucent, its surface being smooth. That of the variant, on the contrary, is rather brittle and opaque, and is milky white in colour, in conse({uenco of which the colour of the serosa can barely be seen through the shell and thus a peculiar whitish grey colour is produced. The surface of the shell is not smooth as in the normal shell, but begins to become irregularly corrugated as soon as the ventral plate is formed. There is no depression in the middle, which is a common characteristic of the egg laid by normal breeds. In the spring of 1909, we obtained two batches of grey eggs, one being derived from the univoltine white reared in the district of Hyogoken, and the other which came from Fuktishimanken is derived from the normal divoltine white, " Aobiki." They were reared separately and each of them gave both normal and grey batches, that is to say, the former deposited one grey and one normal batch (Table III) and the latter 1.5 normals and 20 greys (Table II); no mixed batches were produced in these cases. (See Tables II and III.) la the second generation (summer brood of 1909), moths derived from both normal and grey eggs paired inter se, yielded again, with no K. TOYAMA 361 Parent egg TABLE II. Pedigree of the Whitish-Grey Variant, No. '2i. All whitish-grey 1 1 First generation (Spring of 1909) 15 normals + 20 1 grey batches Nm'inal-egged Series. I Grey egged S iries. Number Number of of normal Matings batches Number of grey batches Total batches Number of Matings Number of normal batches Number of grey batches Number of B-grey batches Mixture of G and BG: Total batches econd generation No. 24. 3 4 4 8 24. G 1 2 1 0 — 3 Summer of 1909) „ 6 4 1 5 „ 3 2 5 0 — 7 ,, 21 2 0 2 4* 10 15 0 — 25 „ 22 3 1 4 „ 16 1 2 0 — 3 „ 24» 7 0 7 „ 20 10 10 1 0 0 — 20 1 Totals 20 6 26 „ 16 x 1 0 Totals 25 34 0 — 59 Third generation 24. N 24. 1 34 0 34 24. G 4. 1* 7 13 1 — 21 (Spring of 1910) 2* 41 0 41 ., 4 18 22 4 — 44 2x1 2 0 2 ,, 25 15 9 0 — 24 3 21 0 21 „ 26 9 5 3 — 17 3x1 4 4x1 ri 22 10 0 0 0 5 22 10 ,, 28 18 8 1 — 27 Totals 67 57 9 — 133 5 23 0 23 Totals 158 0 158 ^ourth generation 24. W24. 2. iVl* 2 142 24 0 2(?) 142 26 24 . Gi. Gl.Gl* 7 0 7 36 - 43 Summer of 1910) 11 38 7 — 56 .. 5 5 0 5 _, 8 32 41 24 — 97 7 71 0 71 ,, 11 22 47 27 — 96 8 87 0 87 21 9 31 11 — 51 22 23 66 3 0 0 66 3 v> 28 26 16 0 — 42 Totals 100 173 69 342 Totals 398 2 400 Fifth generation 24. A' 24. 2. No. 1. (iV 10, 24 . G 4.(3 1. G 1.1 G6 ) 0 18 14 1 33 14, 18, 22, 25) 7 0 19 17 0 36 Mixture of 5 ) batches f do. No. 12 38 47 0 0 38 47 Mixture of batches 16 22 24 5 0 0 2t 2t 4 18 5 56 9 18 8 40 u 0 6 8 13 36 21 Totals 85 0 85 106 Totals 120 106 * Those matings marked with an asterisk are the parent of next generation, t Normal eggs found in these matings are not true normal form, the shell being rather thin when compared with that of normals. J:BG = B-greys. Jonrn. of Gen. ii 25 15 245 362 Matcnud Inheritance ami MendeUstn exception, normal and grey batches. Thus five matings of the normal series from the divoltiae breed yielded 20 normals and 6 greys i six matings of the grey series from the same breed similarly gave 25 normals and 35 greys. (See Table II.) The third generation of the normal series which were reared in the spring of 1910 yielded all normal egged batches which when inbred remained true to parents in subsequent generations : i.e. they became homozygous. This was not the case in the grey series. Five matings of the grey series in the spring of 1910 (third generation) gave 67 normals and 67 greys, in addition nine batches of a new variant which we have as yet never observed in our breeds. This new variant is characterized by the thin translucent shell which has fine wrinkles over it and by a shape a little longer than normal eggs. Tliere is no depression iu the middle. We shall call this kind of variant " B-grey," since it more resembles the grey form than the normal ones. In the case of moths laying B-grey eggs the actual number of eggs laid is always much smaller than the number laid by moths laying eggs of normal colour, even though the parents belong to the same batch. The worms which came out from the BG are so weak that we can hardly get any moth and consequently we are unable to trace the order of its inheritance. Of six grey matings of the grey series which were reared in the summer of the same year (fourth generation), five again yielded 100 normals, 173 greys and G9 B-grey batches. One mating, on the contrary, gave no normal eggs except the grey and B-grey, the respective figures obtained being 7 and 36. The fifth generation derived from the grey mating, which in the last generation yielded no normal batches, gave 245 batches in which 120 were grey, 106 B-greys, 5 mixture of grey and B-grey, and 4 which look like an intermediate form between normals and B-greys. Details of figures obtained iu each mating of each generation will be seen in Tables II and III. From the results above quoted, we are able to say that, as in the case of first and second series, both normal and grey characteristics segregate from one another, and it is easier to get rid of the antagonistic characters in the normal than in the grey. The appearance of the new form which may probably be due to the new combination of allelomorphs renders the phenomena of inheritance rather complicated. Hence if we consider the G and BG forms as a single form, the results come in the same category, which was mentioned in the former series of experiments. K. TOYAMA 363 TABLE III. Pedigree of Whitish-grey Eggs derived from the Normal Univoltine White. Parent egg batch, No. 12 All Grey eggs (laid in the Spring of 1908) I First generation (Spring o! 1909) G (1) + "1 N(l) Second generation (Spring of 1910) G (2) + N (i) N (8) I Third generation ^^ (15) + G (16) These figures will be again summarized graphically as below : A. G = Grey egg batch, 2\r=Normal, BG = B-Grey. 1. Parent eggs in 1908 (No. 24) G 1 I {N + G) I 1909 (Spring) 1909 (Summer) A" {N + G) [N + G) 1910 (Spring) all N I I (N + G + BG) 1910 (Summer) all N (G + BG) {N + G + BG) I H- n 1911 (Spring) all N (G + BG) B. 1. Parent eggs 1908 1908 G 1 1 1909 (Spring) 1910 (Spring) 1 (G + 1 1 (G + N) ! all 0 N 4. n 1911 (Spring) (G + N) 25—2 364 Maternal Inheritance and Mendelistn Series 4. The Spindle-sluqwd Eggs (Fig. 1.3). In the early spring of 1909, we obtained half a batch of the egg.s laid by a Japanese normal univoltine white. The egg is long and spindle-shaped, and is slightly pointed at both ends. There is no depression in the middle which is a characteristic common to normal silk-worm eggs. The first generation which was reared in the spring of 1909 gave eggs which were quite normal in shape and other characteristics. The egg-batches obtained were only six in number. The second generation derived from the normal eggs yielded moths which paired inter se deposited 46 batches of eggs in which we found both normal and spindle-shaped ones, the number found in each mating being as follows : Number of Matings Number of normal batches Number of spindle-shaped batches Totals 1 18 5 23 6 15 8 23 Totals 33 13 46 Of 46 batches derived from two normal matings, 13 were spindle- shaped and 33 normal-shaped batches, no mixed ones. In the third generation which was reared in the spring of 1911, both normal and spindle-shaped eggs gave moths which, when inbred, laid two kinds of eggs, normal and spindle-shaped ; the respective figures obtained in each mating are shewn below : Eggs laid Normal Spindle-shaped Number of Matings batches batches Mixture Spindle-shaped egg, No. 1. 10 . 1. 10 I „ 12 „ 24 ) 25 2 — 27 Normal eggs, No. 6 (8 batches) 24 3 1 28 Owing to the gi'eat havoc made by " flacherie," the mortality of worms was so great that we only obtained a small number of moths, yet we are able to prove that both characteristics even when inbred again produce the antagonistic characteristic. Thus the order of inheritance of these characteristics may be represented as below : K. ToYAMA 365 S= spindle-shaped eggs; iV= normal-shaped. Parent eggs ... ... S Eggs of first generation N I 1 I I Eggs of second generation (iV + S) Egg.? of third generation (N + S) (N + S) Although we are not yet able to establish this variant as a constant form, we may infer from the above facts that it comes in the same category as the variants just referred to. Of the various egg-characteristics discussed in the series of experi- ments above referred to, we know that those in the first and second series are derived from the colour of the serosa, those in the third and fourth series from the shell, whose special structui-e gave the egg some characteristics different from normal-shelled eggs. Notwithstanding their origin being different, their order of inherit- ance is nearly the same. Let us now compare the results obtained in the third and fourth series, which are represented as below : 1. The Results of the Third Series. (G and BG are considered to be a single character G.) Parent eggs G I 1 I, I Eggs of first generation ... {N + G) I I I ' 1 I ' 1 I III second ,, ... N {N + G) (N + G) I , I , I I third „ ... N (X + G) I I fourth N (G + N) + G I I fifth ,. ... N G 366 Maternal Inheritance and Mendelism The Results of the Fourth Series. Parent eggs EggB of first generation ,, second ,, „ third I N {N (N I + S) I I I (N + S) In this case, if we consider the parent egg, G in the third series, as the N of the first generation of the fourth series, both results come in a single form which may be represented as below : A = G in the third and N in the fourth series ; B = N in the third and S in the fourth series. Parent eggs B Eggs of first generation ... A second third fourth fifth sixth I — I B B I B I {A + B) A I A I A) I I I I + ~~1 I (A 1 I + B) If we compare the results obtained by the first and the second series of experiments, we can easily see that they behaved in inheritance in a similar manner to those above described, certain inconsistent results being due perhaps to the appearance of divoltine white eggs which prevented the elimination of the antagonistic characteristics during one generation. K. ToYAMA 367 IV. Crossing of various Breeds or Variants possessing DIFFERENT EGG-CHARACTERISTICS. Series 1. Crosses between the wild (Theophila mandarina, M.) and the domesticated {Bombyx mori, L.) mulberry silk-worms. The egg of the wild mulberry silk-worm (Fig. 10, a, b) is deposited in a small group on stems or twigs of the mulberry tree. When newly laid, it is a straw yellow (Fig. 10, b) which with the formation of the blastoderm gradually assumes a brownish tint and at last turns greenish grey (Fig. 10, a). The shape is nearly the same as those of cultivated ones, while the size is little smaller than the latter. The shell is straw yellow and translucent. The egg of the domesticated silk-worm used in this series of experiments is light greenish white when newly oviposited. It gradually assumes, as in the wild form, a brownish tint and turns brownish slate with some shade of purple or pink, i.e. it assumes the normal colour of Japanese silk-worm eggs (Figs. 1, 3, 11). The shell is nearly white, rarely faintly shaded with a greenish, brownish, or other tint. In the spring of 1905, five wild female moths were mated with domesticated males (tetravoltine Tobuhime). They deposited, with no exception, eggs whose characteristics are the same as those of pure wild ones in every respect, such as colour, shape, size and brood character (voltinism). On comparing them with those laid by pure wild parents, we were not able to find any difference at all. Eleven reversed matings (uni-, di-, and tetravoltine females with wild males) gave, on the contrary, eggs which are similar in shape, colour and voltinism to those of pure domesticated ones (Fig. 11). Even the eye of experienced breeders is not able to distinguish the cross-bred eggs from those laid by maternal pure breeds. Other five batches derived from divoltine females in the spring brood mated with wild males are all divoltine white in colour, and thus the order of inheritance is entirely maternal, no paternal influence being observed in those reciprocal matings. The worms which emerged from the reciprocal F-^ eggs were reared in the summer of the same year. Moths derived from the eggs laid by the wild female matings (five matings) gave 56 batches of eggs, all 368 Maternal Inheritance and Mendelism of them being uaiform in their characteristics. When oviposited, they were light greenish yellow and much lighter in colour than the F^ and gradually assumed a brownish colour which finally turned a greenish slate. Although they resemble the F^ eggs very much in colour, they are darker and the colours are more decided than the latter, and have no dirty or dull shade which is common in the eggs of Theophila. The shell is of clear gi-eenish yellow and deeper than that of the F^ or pure wild forms. Therefore, we may easily distinguish F^ eggs from F„ eggs. There are, however, certain variations of colour in the same batch or between different batches, but no trace of the colour-characteristics of the domesticated parents, and consequently we may say that the colijur-characteristic derived from the wild parent dominates over that from the domesticated parent. In the spring of 1906, we reared worms derived from the F.2 eggs. Owing to the prevalence of grasserie and diarrhoea, all of them died without attaining their mature stage. It will be noted here that, as far as our experiments went, the hybrid form is much more easily injured by those diseases than the pure domesticated form, especially in the case where the male parents were of the wild form. It is, therefore, very difficult to rear a good supply of the hybrid form for experiments. We were therefore compelled to continue our experiments with back- crossed form paired with domesticated one which is healthier than the first cross. Back-crosses. In the summer of 1905, cross-bred moths from the F^ eggs were mated with pure domesticated ones. Reciprocal matings gave, as in the case of -F,, diametrically opposite results. Four F^ females mated with pure domesticated males gave all greenish slate eggs whose colour is quite the same as that of the F„ eggs before mentioned, while those laid by 12 domesticated females (tetravoltine white) mated with the cross-bred F^ males produced, without exception, eggs with character- istics quite maternal. The worms derived from the former matings all died in consequence of the two diseases above mentioned, while those from the latter, being much more able to resist those diseases, gave some moths in the end of the autumn of 1905, that is to say, the third brood of 1905. 36 batches of eggs resulted from the intei' se breeding, in which we found many different coloured batches as is shewn below : K. TOYAMA Number of Matings Greenish-slate batches Japanese normal colour-batches Mixture of various shaded eggs Totals I 0 2 3 5 lb 1 0 0 1 II fl 9 8 5 22 lie 0 2 1 3 He 3 0 2 5 869 Totals 18 12 11 36 Of 36 batches or matings obtained, 13 were greenish slate as in their parents, 12 Japanese normal colour, the rest being a mixture of both kinds of eggs and some intermediate ones in various pro- portions. Owing to certain variations found in a batch, or between various batches, and the scanty number of matings obtained from each parent, we are unable to give the exact numerical proportions of these various coloured batches, but we certainly see that the uniform coloured F.2 characteristic disintegrated into various coloured forms. In the spring of 1906, we reared worms derived from normal- coloured eggs. Moths paired inter se gave all divoltine white eggs. The fourth generation from these divoltine white eggs were reared in the summer of 1906. Three matings gave three kinds of egg batches, as in the former generations, namely : Number of Matings Greenish-slate Japanese normals Mixtm-e Totals Ila, 3 5 7 3 15 „ 4 4 10 5 19 „ 5 2 4 10 16 In 1907, we made similar experiments. The worms which came out from normal-coloured batches gave all divoltine white eggs in the spring. The summer broods gave 30 batches of eggs, all of them being of the normal Japanese colour. Since then they have bred true to parents, never giving any greenish coloured ones. Resume : r = greenish-slate coloured batches like those laid by pure Theophila. N= brownish-slate coloured egg batches, common to normal Japanese breeds. ilf= mixture of those two kinds of eggs above-mentioned and some intermediate coloured eggs. ir= divoltine white. (1) C^) ( ? Theophila x tf Bombvx) ( ? Bombyx x i Theophila) I ■ I Fl eggs T N I I F-j eggs T T 370 Maternal Inheritance and Mendelism Back-Grossing. (1) (2) ( ? F[ X i Bombyx) ( ? Bombyx x i F{) I I Eggs of first back-crossinK T N I I T second „ (T + N + M) I third ,, W I fourth ,, {T + N + M) I fifth „ W I constant We see that the phenomena of inheritance observed in Fi eggs and in back -crosses are exactly maternal, no trace of paternal inHiience, and that both Tlieophila and Bomby.c colonred characteristics segregate from each other, and may be extracted again in their original form. Series 2. Crosses between the Whitish grey-egged a)id Normal-egged forms. In the spring of 1909, we made crosses between the whitish grey- egged and the normal-egged breeds. The grey-egged breed nsed in this series of experiments was the very same breed used in the second series of experiments before mentioned, that is to say. Grey No. 24. Normal- egged breeds were: (1) tetravoltine white (Onodahime), (2) divoltine albino extracted from a cross between divoltine " Chiyodzuru " and "Chiisu" albino, (S) divoltine " Shinkawachi," and (4) " /T^ albino" extracted from a cross between Japanese tetravoltine white and the wild mulberry silk-worm. (a) Tetravoltine normal-egged female.s (Onodahime) mated with males of Grey No. 24. Three matiugs were made in the spring of 1909 which gave all normal divoltine white F^ eggs. Of the summer broods derived from the Fi eggs, those from two batches yielded both normal and grey (34 normals and 15 greys) F„ batches and the remainder only normal batches. Some of the F^ batches hatched in August, which were the third brood of 1909. Seven batches were reared sepaiately and when K. TOYAMA 371 matured gave, without any exception, normal ^3 batches, the number being 461. Their posterity only gave one batch of grey eggs in four successive generations during which they produced 1042 batches. Thus we may safely say that some of the normal-egged form which appeared in the F^ are homozygous from their first appearance. Descendants of the F„ grey batches derived from the same summer brood, on the contrary, produced the antagonistic normal-coloured batches in F^ (the spring of 1910). Of five matings reared, four yielded grey, normal, and B-grey F^ batches, while one gave grey and B-grey, no normal batches. In the former, we found 20 normal, 34 grey, and 5 B-grey batches, and in the latter 6 greys and 3 B-greys. In the summer of 1910 we again reared nine grey batches, one of which was derived from a mating which did not produce any normal eggs in the last generation. Each of them yielded three kinds of Ft batches, normal, grey, and B-grey, except three matings (Nos. 2. 4. 1 ; 2. 8. 6 ; 2. 8. 4) which gave only grey and B-grey batches. The total number of F^ batches obtained in the former matings was 78 (26'5 7o) normals, 126 greys, and 90 B-greys, and in the latter 51 greys and 30 B-greys. Two B-grey F^ batches which were reared in the same season gave only four Ft batches, one being grey and three B-greys, no normal batches. The autumn (1910) brood derived from the summer grey brood, which laid only grey and B-grey batches, gave F^ batches, in which we again found normal batches, but their proportion became gradually lessened as the figures show, namely, of five matings derived from the grey mating No. 6 which did not produce any normal batches in the summer, two gave 28 normals, 71 greys, 39 B-greys, Fr^ batches, the remainder 68 greys and 55 B-greys. Of seven derived from No. 1 mating, which as in the former gave no normals in the summer, five gave three kinds of F^ batches (15 normals, 52 greys and 27 B-greys) and two no normal batches (12 greys, 18 B-greys). In the former lineage, therefore, the proportion of normal batches is 20 7o and in the latter 14-4 7„. In the spring of 1911, we again reared nine grey batches derived from the brood which produced no normal batches in the last generation. They gave 103 F^, batches of eggs of which 49 were grey, 49 B-greys and five a mixture of both kinds of batches. Ten batches of B-grey eggs derived from the same parents as above matings were reared, but all of them died before attaining maturity. 372 Maternal Inheritance and Mendelism TABLE IV. Crossing between Tetravoltine Normal-egged and Heterozygous Grey-egged Variant No. 24. ( ? Normal-egged x s Grey-egged variant) F, eggB (Spring, 1909) Fo eggs (Summer, 1909) All normals 1 (Nos. 1, 2, 3) o. of Matings 1" 2* 3* No, of normals 6 16 18 No. of greys 0 14 1 Totals 6 30 19 Totals Normal-egged Series. Year Number of Matings Normal Grey B-grey Totals F3 1909 1. 1* 71 0 0 71 (August) 1.2 61 0 0 61 2.2* 42 0 0 42 3.1 87 0 0 87 3. 2 7 0 0 7 3. 3 49 0 0 49 3.6 49 0 0 49 Totals 366 0 0 366 Ft 1910 I. 1. 7 39 0 0 39 (Spring) ., 10 28 0 0 28 „ 16 27 0 0 27 ,, 23 28 0 i(;') 29 „ 20 50 0 0 50 2. 2. 2 32 0 0 32 „ 4 30 0 0 30 ,. 11 28 0 0 28 ., T 39 0 0 39 ,, 18 22 0 0 22 Totals 323 0 1 324 F5 1910 2. 2. 7. 4 96 0 0 96 (Summer) 5* 76 0 0 76 7 24 0 0 24 ,. 11 27 0 0 27 „ 12 4 0 0 4 Totals 227 227 40 Gn 'iz-esig ed S •iries. Number of Matings Normal (irey B-grey Mixed Totals F, 2. !• M 4* 0 7 6 3 — 9 10 1 — 18 .. 5* 11 13 0 — 24 ,. 8* 1 7 0 — 8 „ 16* 1 4 4 — 9 Totals 20 34 5 59 F4 2. 1. 5 5 8 4 17 2. 4. 1* 0 27 9 — 36 2. 10. 8 16 27 13 — 56 2. 16. 3 29 30 29 — 88 2. 5. 2 (1 34 20 — 63 2. 5. 6 11 20 12 — 43 2. 8. 4 0 1 1 — 2 2. 8. 3 8 7 12 — 27 2. 8. 6* 0 23 20 — 43 Totals 3 matings 0 51 30 — 81 6 78 126 90 — 294 No. 2. 1 BG 1 0 1 0 — 1 „ 4.7 0 0 3 — 3 • Those marked with an asterisk are the parents of next generation. K. ToYAMA 373 TABLE IV.— {continued). Crossing between Tetravoltine Normal-er/ijed and Heterozygous Grey-egged Variant No. 24. Nornud-egged Series. Year Number of Matings Normal Grey B-grey Totals ; 1910 (Autumn) 2. 2. 7. 5. 4 13* 11 17 20 77 22 80 39 37 41 29 Totals 24S F-! 1911 2.2.7.5.13. 3i (Spring) y 213 22 80 39 37 41 29 248 243 Grey-egged Series. Number of Matings Nonnal Grey B-grey Mixed Totals 2. 8. H. 1 4 6 ,, 11 ,, 44* 12 0 16 0 0 39 2 32 14 42 21 2 18 18 3-5 Totals 72 4 66 32 77 Totals 2 matings 28 71 39 138 3 0 58 55 — 113 2. 8. 6. BG 3 0 11 11 _ 22 BG 9 0 1 3 — 4 „ BG12 0 0 1 — 1 Totals 0 12 15 — 27 2. 4. 1. 8 6 15 8 29 9 0 8 12 — 20 12 11 14 7 — 32 17 2 13 6 — 21 20 3 6 3 — 12 27 0 4 6 — 10 19 3 4 3 — 10 Totals 5 matings 25 52 27 104 2 0 12 18 — 30 Fs 2. 8. 6. 44. 3 0 5 8 13 6 0 4 1 — 5 21 0 2 5 — 7 66 0 3 5 — 8 9fc 0 15 9 3 27 126 0 1 2 1 4 12c 0 7 12 0 19 16c 0 6 6 1 13 19c 0 6 1 0 7 49 49 103 * Those marked with an asterisk are the parents of next generation. 374 Maternal Inheritance and MendeUsni The respective figures obtained in each mating in every generation are represented in Table IV which will be summarized as below : F\ eggs N (Normal x grey No. 24) r ~1 Fj eggs .\ Q ' + , 8 (B-grey 0 0 0 0 0 0 series 1 11 0 0 2 14 ) 30 10 4 6 0 3 31 21 4 6 2 17 Grey se ries Grey 1 series ^'5 eggs (Spring, 1911) N umber of Parent Normal Grey B -grey Total Number of Parent Normal Grey B-grey Total 6. 7. 3 1 (4 and 5) ) 2 3 6 11 6. 16. 12 I (5 and 16) | 8 16 0 24 * Pai ents of next generation. In the uext generation paired inte7' se, both series again yielded only normal-egged F^ batches, the number of batches produced in the former series being 66 and in the latter 123. Now it is quite certain that in these matings there is no grey factor which has lain dormant as in the former matings. The facts obtained in these three series of experiments and those from the second series of the line breeding suggest to us, firstly that among the eggs of grey-batch No. 24, there are two kinds of grey eggs, one having the grey factor in its zygotic composition, while another has no grey factor, in spite of its being grey in colour ; that is to say, some grey eggs are heterozygous for the normal factor, some homozygous • 76 Matenml Inheritance and Memlelisni normals ; secondlij that the normal and the grey segregate from each other in their succeeding generation as other Mendelian characters do ; thirdly that it is much easier to free the normal form from the antagonistic character than the grey; and, lastly, that the normal form does not produce any other form when it becomes free from the grey form, while the grey form segregates into another form even after being freed from the normal form. From this fact we may safely infer that the grey is more complicated in its constitution than the normal. Series 3. Crosses between Yellow and White forms of Japanese Tetravoltine Breed, " Onodahime." (Fig. 9, a and b.) Normal Japanese tetravoltine breeds are generally white cocoon- spinners, as far as we are aware. In the year 190.5, we obtained a mixed breed consisting of white and yellow cocoon-spinners, the latter being a yellow-blooded form. Each form was reared separately and was established as a constant form. In the spring of 1907 reciprocal crossings between these forms were made. Yellow females mated with white males gave Fj eggs which are all yellow when newly laid' (Fig. 9, b). This is the characteristic egg- colour of the yellow form. The reversed mating gave, on the contrary, all pale white Fi eggs (Fig. 9, a) which is also the characteristic colour of the white form. It will be necessary to note here that the colour of newly laid eggs is determined by that of the shell and the yolk, both of them being maternal in their origin. The worms which came out from the reciprocal F, eggs were reared in the late autumn of the same year. All the worms were yellow- blooded and spun yellow cocoons without any exception. The moths paired inter se gave all yellow F„ eggs which are quite the same as those laid by the pure yellow forms. In the spring of 1908, the F^ yellow eggs gave two kinds of worms, the one being yellow-blooded, the other white-blooded ; the total figures found in those matings are shown below : — Number Number of yellow- Number of white- of Group blooded worms blooded worms Totals I 485 169 654 II 567 160 727 Totals ... ... 1,052 329 1,381 Mendelian expectation 1,035 345 1,380 ' In this series of experiments, we only refer to the colour of the egg when newly laid, i.e. the colour of eggs before the formation of the blastoderm takes place. K. TOYAMA 377 The moths derived from these yellow- and white-blooded worms were paired in the following ways : I s White-blooded moths x i White-blooded II $ White „ „ X d- Yellow III ? Yellow „ „ X ^ Yellow „ IV ? Yellow „ „ X i White They gave the results which are tabulated below : — Parents Worms which emerged from the egg N'umber Matings Colour of the eggs laid ^A.^ Group of Female Male Yellow White Totals I I No. 9 white white pale white 0 all white all white II " la 10 13 21 •• )' )» " '• •• II II No. 6 l.S 14 white yellow pale white 59 17 242 51 0 0 110 17 242 )» »f 23 >i " " 27 19 46 III II No. 9 3 4 yellow yellow I' brownish yellow 0 109 39 0 30 14 0 139 53 ,, ,, 5 ,, ,, greenish yellow 0 0 0 „ ,, 11 ,, ,, brownish yellow 71 17 88 ,, ,, 16 ,, t» M JJ 0 0 0 •■ " 24 " ■• greenish yellow 54 13 67 Totals 273 74 347 IV I No. 6 yellow white yellow 65 55 120 As the Table shews, if yellow-blooded females (both homozygous and heterozygous) are used, whether they are mated with their own males or other white males, the results are always the production of brownish or greenish yellow eggs which is a characteristic of the yellow-blooded form. In like manner, white-blooded females mated with yellows (homo- and heterozygous) or whites gave all whitish eggs, characteristic of the white form. Thus we may say in thi^ case as in the other cases before cited, the colour characteristics of the egg are not influenced by the zygotic composition of the egg after fertilization, but by their maternal zygotic constitution before fertilization, and therefore there is no sign of male characteristics to be seen in the egg, but in the larval stage their relation is quite Mendelian. Journ. of Gen. ii 26 378 Maternal Inheritance and Mendelisni Resume : r=,yellow eggs; ir=white eggs; (j/) = yellow-blooded worms and moths; (w) = white- blooded worms and moths. (1) C^) F, eggs .„ ... y W WoriuB and moths (u) [y) I I F2 eggs y y I I Worms and moths l-^(y) = l("')i I I {? ()/) X i{w)\ { ?(!0) X t M The extracted normal breed »> " „' 12 normal dark colour If n 1) 13 >» >) 11 »» n Divoltine white (Renzoku) 14 15 16 5> 1) K. TOYAMA 383 Of eight matings, five gave all normal dark eggs, while three gave all divoltine white eggs, which is the maternal chai'acteristic of tetra- or divoltine females in their spring brood. 2. ( $ crimson breed x ^ normal breed.) The reversed matings gave results identical with those represented. Female parent I Crimson Male parent Tetravoltine Onodahime )» 1' The extracted normal-egged \ foiTB from the cross be- 1 tween Bombyx mori and [ Theophila mandarina j Chinese ' ' Dragon horn " Number of Matings 4 5 Eggs laid (f i) normal dark 2 and 3 divoltine white greenish slate The results of the reciprocal matings shew us that in the Fi eggs normal coloured or greenish coloured characteristics dominate over the crimson, while the voltine characteristics are, as in other egg-character- istics before enumerated, maternal in inheritance. B. F„ Eggs. The worms and moths derived from the reciprocal normal-coloured ^1 eggs in the summer of 1910 were all dark-eyed, and the moths paired inte?- se gave the following F2 eggs : Matings Number of Matings Eggs laid by each moth Normal Crimson Totals /6. 1 342 136 478 6.2 294 103 397 6.8 369 103 472 6. 9 374 103 477 ? Tetravoltine " Onodahime " / 0. 10 314 124 438 j 1 12 248 83 331 >» ) 8 312 117 429 i» ' 15 3 : 1 Back-crossing of F^ Dark-eyed Moths tuith extracted Crimson-eyed Moths. Fi dark-eyed moths derived from the mating, $ crimson x {/" tetra- voltine white, were mated with crimson-eyed males derived from the F„ eggs of the mating, $ tetravoltine x 3 306 141 447 »» )» 14 367 104 471 Totals Grand totals Expectation 1077 2152 2156i 357 723 7185 1434 2875 2875 These figures suggest to us at once that the crimson-coloured characteristic is a Mendelian one, recessive to the normal-coloured as is tlie former crimson breed. We reared these eggs separately in the spring of 1910. Crimson-coloured eggs from two batches of the second breed gave, without any exception, crimson-eyed worms and moths, while normal-coloured gave all normal-eyed worms and moths. Both K. TOYAMA 387 crimson and normal-eyed moths derived from the mixed batches of the above breeds when paired inter se oviposited the following batches : W^= normal-eyed ; E = crimson-eyed moths. Parent Moths Eggs laid Names of breeds ? d Normals Crimsons Total Univoltine " Ghinpaku " No. 8. 8 N X N 114 45 159 No. 8. 9 N X N 334 92 426 No. 13. 8 N X N 459 105 564 No. 13. 9 N X N 838 106 444 No. 13. 10 N X N all noi mals Divoltine "Tamanashi" No. 1 R X R No. 3 R X R No. 14, Nos. 8—14 R X R all divoltine white eggs As the figures shew,certain normal-eyed matings gave all normal dark- coloured eggs while others gave mixed batches (3 normals : 1 crimson). The lineage of the crimson-eyed matings which yielded all divoltine white eggs remained true to parents in their successive generations, and gave crimson-coloured eggs without exception in the summer brood. The order of inheritance of these characteristics is in exact accord- ance with the F3 of a monohybrid cross, and the parental mixed eggs given by Mr Saito were undoubtedly F2 eggs between the crimson and normal-coloured forms. Now we may clearly see that those crimson- coloured characteristics found in the three different breeds are in the same nature and Meudelize in the normal order, the crimson beintr hypostatic to the normal-coloured one. Resume : Ji = crimson; N'=normal. (N X R) (reciprocal) Fi eggs N F, „ {3N : IR) 1 1 1 1 ^3 M N (3N : IR) ii (F, X R) 2 J) (IN : IR) 388 Maternal Inheritance and MendeUsm Greater Death-rate of the Crimson- coloured Egg. During our experiments with the crimson breeds, either with the original divoltine or other extracted forms from cross-bred or mixed breeds, it has struck us that the number of worms which came out in spring from these eggs was very small, sometimes over 90 °/„ were found to be dead ; even in the case where the crimson eggs were found mixed with normal ones in the same batch, the mortality is much greater than that of the normal-coloured eggs. We give here certain figures of the death-rate observed in the crimson-coloured eggs laid by some breeds. Fifteen batches selected at random from 84 crimson-coloured batches laid by the summer brood of the extracted crimson form, from the cross between the divoltine crimson and tetravoltine normal-coloured " Ono- dahime," gave the following figures : TABLE VI. Number of batches Total number of eggs laid Number of dead eggs Death-rate 1 377 341 90-4 °/o 2 368 269 73°/, 3 348 342 98-2% 4 439 389 88-6 % 5 413 405 97-1 °/o 6 283 321 88-1 % 7 379 364 96% 8 277 243 87-7 "U 9 438 318 n-&°u 10 365 149 40-8 °/, 11 254 136 53-5 % 12 304 244 80-2 °/„ 13 319 284 89% 14 424 403 95-2 % 15 446 360 80-7 7o Totals 5434 4568 84% The average death-rate was 84'/^, ranging from 40"8 7o to 98 7o ii each batch. In 42 batches of eggs derived from the same breed, we have counted 1.5,194 eggs, of which 12,796 eggs were found dead in the sjjring; i.e. a death-rate of 84 "Z^^. In the eggs laid by a cross-bred crimson form (a cross between an extracted crimson from the cross, " Divoltine crimson x Divoltine Chiyodzuru," and the crimson derived from the divoltine " Tamanashi ") a considerably smaller percentage of dead eggs was noted than in the cross between divoltine crimson and tetravoltine white. K. TOYAMA TABLE VII. Number of batches Total number of eggs laid Number of dead eggs Death-rate 1 481 52 10-8 % 2 487 45 9-2 °/o 3 481 52 10-8 °/o 4 466 3 0-6 7a 5 471 260 55-2 =/, 6 476 241 50-6 % 7 514 90 17-6 °U 8 543 169 31-1 % 9 515 342 66-9 7, 10 490 16 3-2 % 11 529 377 71-2 % 12 471 45 9-5 % 13 459 223 48-5 °U 14 554 3 0-5 7o 15 477 224 47-5 % 389 Totals 7414 2142 28-8 % In this crimson form the average death-rate is only 28'8 °/^ ; in certain matings nearly all the eggs were hatched, while in some others the death-rate mounted as high as 71'2 °/^. In other crimson batches laid by an extracted crimson form derived from a cross between the divoltine crimson and " E III " breed (an extracted breed from a cross between the wild mulberry silk-worm and tetravoltine " Tobuhime "), the figures quoted below were given : TABLE VIIL Number of batches Total number of eggs laid Number of dead eggs Death-rate 1 234 181 77-3 % 2 383 348 90-8 7o 3 335 102 30'4 7, 4 467 329 70-4 % 5 360 66 18-3 % 6 248 192 79-0 % 7 326 303 92-9 "U 8 261 233 89-2 % 9 362 199 54-9 °/o 10 277 153 55-2 % 11 394 283 71-8 % 12 313 279 89-1 % 13 340 322 94-7 "U 14 391 341 87-2 7„ 15 374 355 94-9 °/o Totals 5065 3686 72 7o 390 Maternal Inheritance and Mendelism In this form the death-rate is 72 7o. varying, in individual cases, from 18-3% to 94-9%. We have observed moreover that the death of the embryo inside the egg took place in its earlier stage. So we often found some dead eggs in August or September when a white patch appeared in one side of the Qgg (Fig. 8) which gradually became enlarged in size and at last the clear crimson colour became paler, while others were found dead after the embryo had completely developed. The majority of the deaths seem to occur, however, in the earlier developmental stage of the embryo. Even in the same breed, the death-rate differed greatly according to the colour of the es.s, and the voltine characters. Hence the divoltine white eggs laid by the very same breed which laid the eggs recorded in Table VI yielded a much smaller number of dead eggs than in the univoltine coloured eggs. Ten batches of eggs selected at random from fifty divoltine white egg-batches gave the following figures : TABLE IX. Number of batches Total number of eggs laid Number of dead eggs Death-rate 7 191 60 31-4 °/o 8 361 18 4-9 °/o 9 111 51 45-9 % 10 329 168 51°/o 11 272 196 72°/o 12 309 12 3-8 7o 13 186 18 9-6 "k 13a 272 164 61-4 % 14 413 64 15-5 % 15 381 78 20-8 °/, Totals 2825 829 29-3 % that is to say, the average death-rate is 29-3 7o. which varies from 3*8 7,, to 72°/„ in individual batches. The average death-rate found in fifty batches of eggs laid by the same breed is 19 7^, while iu the case of univoltine eggs it is 84%, as already recorded in Table VI. In certain cases it occurred that some crimson-coloured eggs hatched in the summer. The death-rate of such divoltine crimson-coloured eggs was nearly the same as that of the white divoltine eggs. Even more striking facts were observed when we examined the number of dead eggs found in the batches in which three different coloured eggs, normal, crimson, and albino, were found. These are the F„ eggs laid by the cross, " H" albino and the divoltine crimson breed. K. TOYAMA 501 TABLE X. Normal eggs Number of batches 1 2 3 4. 5 Total number Dead of eggs eggs Crimson eggs Albiuo eggs 194 209 195 213 213 33 64 23 23 79 Death-rate 17°/o 30-5 X 13-8 -I, 10-7 % 37% Total Dead 95 77 66 99 75 94 49 76 61 62 Death-rate 74-2 °/„ 76-7 "=/„ 81-3 X 64-8 "lo Total 91 86 88 99 87 Dead 12 7 30 22 5 Death-rate 13-1 °/, 8-1 7„ 34°/c 22-2 % 5-7 % Totals 1024 222 21-6 % 429 325 75-7 % 451 76 16-8 % In spite of their being laid by the same parents, the mortality in those eggs whose colour was crimson was much greater than the others. While in normal and white-coloured eggs, the percentage of deaths was only 21"6 7o and 16'8°/^ respectively, that of the crimson eggs was 75"7°/^. Other ten similar batches gave the following figures: Normal eggs Crimson eggs Albino eggs Total number 2315 956 1076 Number of dead eggs 406 650 288 Death-rate 17-5 °/o 67-9 °/„ 26-7 % The facts above enumerated taught us that in every case in every breed which we have studied, those eggs coloured crimson have a greater death-rate than normal-coloured eggs, while divoltine eggs which are crimson in colour did not shew so high a death-rate as univoltine crimson-coloured eggs. These facts led us to conclude that the embryo of crimson -coloured eggs is not so long-lived as that in the 'normal- coloured eggs. As to the cause of the early death of the embryo of the crimson- coloured eggs, we are quite ignorant at present, but we are inclined to believe that it may be due to the lack of certain pigments in the serosa which in some way help the respiration of the embryo during its development. V. General Considerations. From the results of these series of experiments in both line and cross breedings above quoted, it now becomes clear that (1) those egg- characteristics above enumerated, except in the crimson breed, are determined by the characteristics of the female parent, on account of whicTi the paternal characteristics even when dominant are almost negligible in their influence upon the character of the egg, that is to say, phenomena of inheritance are maternal ; (2) gametic segrega- tion of parental characteristics takes place as in normal Meudelian 392 Maternal Inheritance and Mendelisin allelomorphism ; and (3) iti certaia geueratious, both parental character- istics even when inbred give rise to the antagonistic characteristics which at first suggests that there is a departure from the normal rules. Suppose, now, there are certain Mendelian characteristics which behave as maternal in inheritance. If they were reciprocally mated, what would be the result as regards their offspring ? Let D represent a dominant and R a recessive factor, the results of their reciprocal matings would be diametrically opposite. In the case of a Z) female mated with an R male, the resulting ^i eggs would be all D, while an R female mated with a D male would give all R F^ eggs, in spite of their zygotic constitutions being the same in both matings, namely, DR. And therefore, all the worms and moths derived from the ^i D or R eggs will have the constitution DR, in which the D behaves as an active factor in determining their characteristics. In the same way the egg- cell which has the composition of DR during its development in the parent body is influenced by the D factor only, and consequently after segregation when it lost the antagonistic factor and became pure D or R, it retains the D characteristic before acquired. Thus the results of fertilization will be the production of all normal-coloured F^ batches. Zygotically considered, however, the F„ D eggs are not the same in their constitution. As the result of the fertilization, some of them will be DD, some BR and the rest RR. Consequently, the constitution of the F., moths derived from the F„ D eggs will be a mixture of DD, DR and RR. Thus all the F., eggs, whether fertilized with D ox R sperma- tozoon, will be all D characterized. As there is no means in this case of distinguishing a DD worm or moth from a DR or an RR, random matings between them are expected to occur. The result will be as below : Colour of the Fs eggs laid Zygotic composition of the egg a. i DD X S DD = D DD b. i DD X i DR = D (DD + DR) c. ? DD X i RR = D DR a. ? DK X J DD = D {DD + DR) b. i DR X S DR = D {DD + DR + RR) c. i DR X i RR = D {DR + RR) a. ^ RR X i DD = B DR 'b. $ RR X i DR = R {DR + RR) c. ? RR X i RR = R RR In some cases female DD moths will mate with DD, DR or RR males (series 1), in some others DR females will mate with the same three kinds of males (series 2). The same holds good in the case of RR K. ToYAMA 393 females (series 3). The F,, eggs laid by the first and the second series of matings will be all D batches, since all females are DR or DD. For the same reason, the third series of matings will give all R batches. The Fs eggs derived from the Fo moths paired inter se will be, therefore, a mixture of D and R batches in certain proportions. If we assume that the number of males and females found in each batch is nearly the same, the proportion of D and R batches laid by inter se moths derived from an F„ D batch would be 6i) : 3i? or 2D : \R. As in the case of the F., the zygotic constitution of F^ D and R batches is not simple D or R. As the formulae quoted just above shew, the constitution of certain F.^ D batches is DD (series 1 a), some batches DR (series 1 c), some a mixture of DD and DR (series 1 h and series 2 a), or DR and RR (series 2 c), and the rest DD, DR and RR (series 2 b). We get similar results in the case of the F, R eggs, some batches being DR (series 3«), some (series 3 c) RR, and the rest (series 3 6) a mixture of DR and RR. If moths derived from F^ D or R batches were inbred, what will be the result in the dominant series ? In Fi D batches, as we have already observed, there are five different kinds of batches whose zygotic compositions are respectively : (1) DD, (2) (DR +DD), (3) DR, (4) (DD + DR + RR), (5) (DR + RR). The moths derived from each kind paired inter se will produce the following Ft batches : Matinj; 1. DD inter se = DD x DD^ 2. (DR + 1)D) inter se = Zygotic comjiosition DD Outward appear- ance of F^ eggs D iDE X s DR = {DD + DR + RB) D ? Ci? X i DD = (DD + DR) D i DD X s DD=DD D iDDx i DR = {DD + DR) D 3. DR inter se = 9DRx i DR = (DD + DR + RR) D 4. {DD + DR + RR) inter se = /-I. iDD X i DD = DD D •i. ^DD X i DR = {DD + DR) D 3. 2 DD X i RR = DR D 4. iDRx 6 DD = (DD + DR) D 5. 1 DR X i DR = (DD + DR + RR) D 6. i DR X i RR = {DR+ RR) D 7. iRR X s DD = DR R 8. iRR X e DR = (DR + RR) R 9. ?i^i^ X i\ Herbals : Their Origin and Evolution. A Chapter in the History of Botany, 1470- 1670. By Agnes Arber (Airs E. A. Newell Arber), D.Sc, F.L.S., Fellow of Netvnham College, Cambridge, and of University College, London. Royal 8vo, pp. xviii + 254. With frontispiece, 21 plates, and 113 text-figures. Price loj-. hd. net. Extract from the Preface The main object of the present book is to trace in outHne the evolution of the printed herbal in Europe between the years 1470 and 1670, primarily from a botanical, and second- arily from an artistic standpoint The titles of the principal botanical works, which were published between 1470 and 1670, , are given in Appendix I. The book is founded mainly upon a study of the herbals themselves....! have also drawn freely upon the historical and critical literature dealing with the period under consideration, to which full references will be found in Appendix II The great majority of the illustrations are reproduced from photographs taken directly from the originals by Mr W. Tams of Cambridge, to whom I am greatly indebted. CONTENTS The Early History of Botany — The Earliest Printed Herbals (Fifteenth Century) — The Early History of the Herbal in England — The Botanical Renaissance of the Sixteenth and Seventeenth Centuries — The Evolution of the Art of Plant Description — The Evolution of Plant Classification — The Evolution of the Art of Botanical Illustration — The Doctrine of Signatures, and Astrological Botany — Conclusions — Appendix I — -Appendix H — Index. Globe. — Mrs Arber may rest assured that her fragrant volume will be cherished in many a quiet home, both for the sake of its subject and the fascinating manner in which she has treated it... Mrs Arber has succeeded to a remarkable degree in retaining in the reader's mind that indefinable impression of sweetness and perfume which the title of her book brings with it.... Of the artistic aspect of the old herbals Mrs Arber has furnished abundant evidence in the liberal fashion in which she has illustrated her book with the woodcuts and plates taken straight from their pages. ...No one will read it without yielding to the seductive charm which Mrs Arber has contrived so delicately to retain. \A special prospectus of this book, including a specimen plate, may be obtained from tJie publishers on application^ Makers of British Botany. A Collection of Biogi^aphies by living botanists. Edited by F. ]V. Oliver. Demy 8vo. pp. viii + 332. With frontispiece, 26 plates and a text-figure. Price (-)S. net. Publishers' Note The present volume represents in somewhat expanded form a course of lectures arranged by the Board of Studies in Botany of the University of London and delivered during the early part of 191 1 in the Botanical Department of University College, London. The ten lectures comprised in the course were delivered by various botanists, the lecturer in each case being either a worker in the same field as, or in some way having a special qualification to deal with, his allotted subject. The seventeen chapters forming the book include these lectures and seven additional chapters. CONTENTS Introduction — Robert Morison 1620-1683 and John Ray 1627-1705, by Sydney Howard Vines — Nehemiah Grew 1641-1712, by Agnes Arber — ■ Stephen Hales 1677-1761, by Sir Francis Darwin — John Hill 1716-1775, by T. G. Hill — Robert Brown 1773-1858, by J. B. Farmer — Sir William Hooker 1785-1865, by F. O. Bower — John Stevens Henslow 1796-1861, by George Henslow — John Lindley 1799— 1865, by Frederick Keeble — ^\'ilham Griffith 1810-1845, by W. H. Lang — Arthur Henfrey 1S19-1859, by F. W. Oliver — William Henry Harvey 1811-1866, by R. Lloyd Praeger — Miles Joseph Berkeley 1803-1889, by George Massee — Sir Joseph Henry Gilbert 1817— 1901, by W. B. Bottomley — William Crawford Williamson 1816--1895, by Dukinfield H. Scott — Harry Marshall Ward 1854-1906, by Sir William Thiselton-Dyer — A sketch of the Professors of Botany in Edinburgh from 1670 until 1887, by Isaac Bayley Balfour — Sir Joseph Dalton Hooker 1817- 191 1, by F. O. Bower — Index. Aberdeen Journal. — No important aspect of the development of botanical science is omitted ; systematic botany, anatomy, physiology, palaeobotany, nuclearcytology, and ecology are each given in proper historical setting, and the survey is both instructive and stimulating This is a book which experienced botanists will find not only of genuine interest, but full of suggestiveness with regard to the development of the science, as all good histories are. Further, it is a book to be highly commended to the attention of young botanists, who will not only find the history of their sul ject pleasantly told, but who will be made to feel the personal spell of those workers most of whose names they are already familiar with, and inspired to enthusiastic effort in their own field. \An illustrated prospectus of this book may be obtained on application to the publishers\ The Story of ottr Trees : in Tuuenty-Jour Lessons. By Margaret M. Gregson, B.A. The Cambridge Nature Study Series. Large Crown Svo. pp. .\ii + i6o. With 75 illustrations. Price 2J-. bd. net. Extract from the General Editor s Preface This book is to help children to study Nature, not to put book study instead of Nature Study. The object of the book is to direct and stimulate both observation and reflection. Many teachers have lately found in trees a convenient topic for lessons, one that can be pursued in town or country, summer or winter, indoors or out-of-doors. There may be other teachers who would gladly give their pupils some training in Nature Study, although they themselves do not pretend to have special knowledge. Such an acknowledgment of ignorance is itself a qualification for one who, an enquirer himself, would lead others to enquire Great pains have been taken in the revision of these chapters to fit them into the natural cycle of the seasons, which is now widely accepted as the best order for nature lessons, and is, indeed, the compulsory order if free use is to be made of fresh material. The supplies necessary for each lesson are clearly indicated. But the lessons have also been adapted (and this is a much more difficult adaptation) to the school year and, again, to the different years in use at different schools The serious enquiries now being made into National Afforestation show that we may have to enlist the sympathy of boys and girls in the planting and protection of new wood- lands A chapter on Forestry and tree planting will, therefore, be welcome The lessons are adapted to classes where the ages range from 14 to 12 or even younger, that is to the higher standards of elementary schools, to preparatory schools, to the lower forms of secondary schools and especially to those who are taught privately at home. Athenaeum. — It is a pleasure, among the worthless books published about nature study in its various branches, to come upon Mrs Margaret Gregson's ' Story of our Trees.' Her clear and exact work, and the excellent drawings and photographs by which it is profusely illustrated, should be of great use to the teacher, as well as the pupil. Byza-ntine and Romanesque Architecture. By Sir Thomas Graham J acks07t, Bart., R.A., Hon. D.C.L. Oxford, Hon. LL.D. Cambridge, Hon. Fellow of Wadham College, Oxford, Associ^ de r Acaddmie Royale de Belgique. Crown 4to. In two volumes. Vol. I, pp. xx + 274. Vol. II, pp. viii + 286. With 165 plates, 4 of which are coloured, and 148 illustrations in the text, a large number being reproduced from the author's own drawings. Bound in cloth, with parchment back lettered and ornamented in gold, gilt top. Price £2. IS. od. net. Extract fro7n the Introduction The modern artist still lies under the necessity of studying the art of the past. To shut our eyes to it, as some younger ardent spirits would have us do, would mean the extinction of all tradition, and with it of art itself. For all art, and all science, is based on inherited knowledge, and every step onward is made from the last vantage won by those who have gone before us and shown the way It will therefore be the object of the following pages not merely to describe but to try and explain the development of architecture from style to style since the decline of classic art in the 3rd and 4th cen- turies of our era, down to the dawn of Gothic architecture, by connecting its constructive details and outward features with those social reasons which served to mould them into the forms we know. From this point of view it is important to compare the rate of progress of the new art in different countries : to mark not only the main current of the move- ment, but the irregular and unequal advances by which it pushed its way in each instance. For though the general set of the movement was all in one direction it advanced much faster in some places than in others, and in each country it took a distinctive national character. For this purpose the comparative and parallel tables of examples at the end of the book will I hope be found useful. It is important too to observe the continuity of architectural history ; how one style gave birth to another ; for no new style was ever invented, but always grew out of an older one ; how this progression from style to style was always unintentional and unconscious : and how revival after depression always began by the attempt to revive an older art, with the result that when art did revive it was always something new, for no dead art was ever made to live again, or ever will be. 6 BYZANTINE AND ROMANESQUE ARCHITECTURE— Continued CONTENTS OF VOLUME I CHAP. Preface. Introduction I Roman architecture II Decay of Roman architecture. Foundation of Constantinople. The Basilican plan III Greek element in the new style. Asiatic influences. Syrian architecture. The Byzantine dome. Abandonment of the Classic Orders. Avoidance of figure sculpture IV The Greek church. Marble and Mosaic. The Pulvino. Capitals V Constantinople. The walls and Porta Aurea. Salonica VI S. Sophia, Constantinople VII Justinian's other churches VIII Iconoclasm IX Later Byzantine architecture X Italo-Byzantine architecture. The first or pre-Gothic period XI Italo-Byzantine architecture. The second or Gothic period XII Italo-Byzantine architecture. The third period under the Exarchate XIII Rome XIV The Lombards. Architectural bathos and revival. Rupture between Rome and Constantinople XV Venice XVI Pisa. Florence. Lucca XVII Lombardy CONTENTS OF VOLUME II XVIII XIX XX XXI XXII XXIII XXIV XXV XXVI XXVII XXVIII XXIX German Romanesque French Romanesque. French Romanesque. French Romanesque. French Romanesque. French Romanesque. French Romanesque. French Romanesque. Aquitaine and Poitou Provence Toulouse Burgundy Auvergne Normandy The Isle of France English Romanesque before the Norman conquest English Romanesque after the Norman conquest English Romanesque after the Norman conquest {cont.) Conclusion Chronological tables of architectural examples. Index [A special 8 pp. prospectus, ivith specimen pages and plates, loill be forwarded on application to the publishers^ The Concept of Sin. By F. R. Tennant, D.D., B.Sc, Author of The Origin and Propag^ation of Sin and of The Sources of the Doctrines of the Fall and Original Sin. Crown 8vo. pp. viii + 2S2. Price i,s. bd. net. Methodist Times. — Dr Tennant's new book is accurately described -in the title. It is not a formal discussion of sin as one of the main topics of Christian theology, but an attempt to find such a concept of sin as will give an adequate interpretation to facts admitted by all. The definition of sin which is thus arrived at eventually is that it is "moral imperfection for which an agent is, in the sight of God, accountable" (page 245)- This concept, it is claimed, is logically perfect, and the only one which can fully satisfy the implications of the most fundamental of Christian doctrines. In addition, it is unimpregnable by psychology, ethics (in the stricter sense), science and historj'. Not the least interesting and valuable parts of Dr Tennant's work are those in which he examines sin in relation to ignorance, temptation and guilt. If anyone wishes to reahse how tremendous a fact sin is, how hard to defeat, how impossible to ignore, and yet how certainly not the ultimate fact in the universe, he cannot do better than study Dr Tennant. The Northern Wliig. — Dr Tennant has read widely on the subject of this volume. But he has done more. He has thought deeply ; and it is the utterance of this study that he has given in his book. The volume is a judicious presentation of the subject, which does not make light of trans- gression, and at the same time clears away many of the ambiguities which frequently attach to terminology relating to sin. The Problem of Evil in Plotinus. By B. A. G. Fuller, someiime Instructor in Philosophy at Haroard University. Crown 8vo. pp. xx + 336. Price js. 6d. net. Publishers" Note In this book the author makes an exhaustive criticism of the way in which one of the central problems of philosophy was treated by the most famous of the Neo-Platonists, and concludes that Plotinus, in spite of the wealth and ingenuity ot his argument, never really escapes from the traditional dilemma • — "either God is not justified or Evil is not explained." Aberdeen Free Press. — This is a work of quite unusual significance. The author has called it "The Problem of Evil in Plotinus." It might as well have been called "A study of the problem of evil in general, with special reference to Plotinus. "...Having stated the attempted solutions of the problem, the author proceeds to a review of the history of the develop- ment of the problem of evil in the history of Greek philosophy. The review is brief, but it may be characterised as a most lucid and competent bit of work... then there is a chapter presenting some general aspects of the Plotinian system... [folio wed by] chapters on metaphysical evil, on physical and moral evil, on matter as the principle of evil, and on the theory of emanation.... On the whole we have not read for a long time a more satisfactory book on a philosophical problem, nor one which in- dicates a more masterly grasp of the evolution of philosophical thought, nor one which shows a higher power of masterly criticism. 8 Cambridge History of English Literature: Volume IX. From Steele and Addison to Pope and Swift. Edited by A. W. Ward, Litt.D., P.B.A., AI aster of Peterhoii.se, and A. R. Waller, M.A., Peterliouse. Royal 8vo. pp. xvi + 6io. Price, in Buckram, gj-. net; in Half-Morocco, 15J. net. CONTENTS CHAP. I Defoe — The Newspaper and the Novel. By Professor W. P. Trent, LL.D., D.C.L. II Steele and Addison. By Harold Routh, M.A. III Pope. By Professor Edward Bensly, M.A. IV Swift. By George Atherton Aitken, M.V.O. V Arbuthnot and Lesser Prose Writers. By G. A. Aitken, M.V.O. VI Lesser Verse Writers. I. By Thomas Seccombe, M.A. II. By Professor George Saintsbury, LL.D., D.Litt., F.B.A. VII Historical and Political Writers. I. Burnet. By A. W. Ward, Litt.D., P.B.A. VIII Hisiorical and Political Writers. II. Bolingbroke. By A. W. Ward, LittD., P.B.A. IX Memoir- Writers, 1715-60. By Thomas Seccombe, M.A. X Writers of Burlesque and Translators. By Charles Whibley, M.A. XI Berkeley and Contemporary Philosophy. By Professor W. R. Sorley, Litt.D., F.B.A. XII William Law and the Mystics. By Caroline F. E. Spurgeon XIII Scholars and Antiquaries. I. Bentley and Classical Scholarship. By James Duff Duff, M.A. II. Antiquaries. By H. G. Aldis, M.A. XIV Scottish Popular Poetry before Burns. By T. F. Henderson XV Education. By Professor J. W. Adamson Bibliographies. Table of Principal Dates. Index of Names Standard. — Quite one of the most interesting periods in the entire annals of English Letters comes into view in the present volume — the ninth of an admirable series. We are confronted with the growth of the newspaper and the novel, the essay raised to the height of a classic, the extension of University learning with its outcome in history and philosophy, and much else that is significant The literary vigour and critical discrimination which marks almost the whole of the present survey is a matter for con- gratulation. 9 —5 Plato : Ion. Edited, xvith introduction and notes, by /. M . Mac pressor, B.A., late Senior Exhibitioner, Balliol College, Oxford, Reader in "Greek in the University of London. Pitt Press Series. Extra fcap. 8vo. pp. xxiv + 46. Price zs. Athenaeum. — Shorter and easier than most of the Platonic dialogues, the " Ion " is suitable for young students, and this edition, well equipped with preface and notes, will form a good introduction to Plato. Dryden : The Preface to the Fables. Edited by W. H. Williams, M.A., Professor of Classics and English Literature in the University of' Tasmania. English Literature for Schools. Extra fcap. 8vo. pp. xii + 36. Price \od. Key to the Exercises in English Composition. By ]V. JMurison, ALA., Senior English Master, Aberdeen G^^ammar School. Crown 8vo. pp. vi+172. Price 4s. 6d. net. Erckmann-Chatrian: LTnvasion ou Le Fou Yegof. Edited, zvith notes and vocabulary, by A. Wilson-Green, M.A., Senior French Master at Radley College. Pitt Press Series. Extra fcap. Bvo. pp. x + 344. Price 3^-. Cambridge Greek Testament for Schools and Colleges. General Editor: R. St John Parry, D.D., Felloiv of Trinity College, Cambridge. Extra fcap. 8vo. With introductions, and notes in English. The Epistle of Paul the Apostle to the Romans. Edited by R. St John Parry, D.D. tp. /+ 244. Price 2,s. 6d. net. ■ The Second Epistle General of Peter and the General Epistle of Jude. Edited by M. R. fames, Litt.D., Provost of Kings ColUge, Cambridge, ft). Ix + 46. Price 2s. 6d. net. 10 The Paragraph Psalter arranged for the use of Choirs. By Brooke Foss U'cstcoit, D.D., D.C.L. Revised and edited by A. H. Mann, M.A., Mus.D. Oxon. Pott 8vo. pp. xx + 276. Bound in red cloth, is.; in leather, \s. bd. Demy 8vo. pp. xx + 312. Bound in red cloth, ^s. This revised edition of the Paragraph Psalter contains a number of new features which have been introduced in order to adapt it more fully to the needs of choirs, and it is the sincere hope of the Reviser that it will prove helpful to the better rendering of the Psalms. Voice Training jf or Choirs and Schools. By C. B. Rootham, M.A., Mus.D., Organist and Choirmastej', St John's College, Cambridge. Fcap. 4to. pp. .xlvi + iio. With 83 Exercises. Price 4J-. net. The Exercises are also published separately for the use of pupils. Price is. 6d. net. Extract front the Preface This little work is an amplification of a paper on Choir- Boy Training read by invitation before the International Congress of Musicians in London (May, 191 1). Since that occasion I have received from several different quarters requests that my paper should appear in book form. After I had decided to respond to these expressions of good-will, it was suggested to me that the project might be extended to meet the requirements of singing-classes in schools, whether of boys or girls. Hence the present form and scope of the work. Music on the Shakespearian Stage. By G. H. Cowling. Crown Bvo. pp. viii+ri6. With a frontispiece and 10 plates. Price 4i-.net Extract from the Introduction The following Essay... is an endeavour to do with the musical stage-directions what has already been done with those relating to other matters, namely, to collect them, and to force them to show their own conclusions. It endeavours to show what kinds of music were used during a play, and when and how the music was performed It concludes by attempting to estimate critically the artistic worth of music to the stage. 1 1 Lord Chatham and the Whig- Opposition. By D. A. JJ 'install ley, AI.A., Felloiv and Lecturer of Trinity College, Cambridge. Demy 8vo. pp. .\ + 46o. With a frontispiece. Price "js. 6a. net. Extract from the Preface Many are the accusations which can be brought against the period which Hes between the formation of Chatham's ministry in July 1766 and the collapse of the whig opposition to Lord North in the summer of 1771 ; but it can scarcely be accused of lacking in either interest or importance. Within those few years the destinies of the nation were determined and the work of the Revolution nullified. Spectator. — Mr Winstanley has used his mss. authorities judiciously and skilfully, and he steers his way with ease among the tortuous intrigues of the period. He is a spirited and graceful writer, and we shall welcome from him further studies in eighteenth-century ])olitics — It is a fascinating and most interesting piece of political history, and Mr Winstanley's book is well worth the study of everyone who cares to watch the slow and difficult growth of our constitutional forms. The Early History of the House of Savoy, looo-i 233. By C. W. Previtd-Orton, M.A., Felloiv of St Johns College, Cambridge. Demy 8vo. pp. x.\ + 492. With 2 maps in pocket. Price \2s. bd. net. Extract from the Preface The following pages contain a study on the history of the House of Savoy until the year 1233. Although many works on portions or on aspects of this period have been written, and though it has formed a part of more than one history with wider scope, such as Cibrario's Storia, delta Monarchia di Savoia, yet there seemed to be room for a new investigation, which should at one and the same time treat the subject with a full discussion of its details and with a comprehensive view of the period as a whole I have taken as my model in a general way the fahrbiicher on the Holy Roman Emperors. That is, I have gone plainly on, discussing events and pro- blems as the times brought them to light and endeavouring to be complete and omit nothing — There will be found in the notes all the important passages of narrative or legal nature on which the text is founded, not merely references to them. 12 A Source Book of English History for the -use of Schools. Edited by Arthur D. Innts, M.A., forvicrly Scholar of Oriel College, Oxford. Volume /, 597- 1603 A.D. Large Crown 8vo. pp. viii + 384. With 31 illustrations. Price 4^'. (>d. Extract from the Editor s Note A series of extracts taken entirely from the work of con- temporary writers. It is intended for use in schools, and its primary purpose is to attract the interest of the student by presenting history to him as it presented itself to the men of the time. The matter chosen has been such as will appeal to the imagination — narratives of striking events in prose and verse, portraits, passages illustrative of life and manners, and so on. The extracts are illustrated throughout by reproductions of authentic portraits, by illustrations taken from old mss., and by photographs of historic scenes. [Volume II is in the press] Elementary Principles of the Roman Private Laiv. By W. IV. Bttckland, M.A., Fellow and Tutor of Gon- ville and Caius College, Cambridge. Demy 8vo. pp. viii + 420. Price \os. 6iay be obtained on applicatio/t] 22 CAMBRIDGE COUNTY GEOGRAPHIES General Editor: F. H. H. Guillemard, M.A., M.D. A series of County Geographies, price i^. bd. each, suitable for general use as hand-books to the various counties and also intended for use in schools. Each volume gives an account of the history, antiquities, architecture, natural history, industries, and physical, geological, and general characteristics of the county, and each has two coloured maps (one physical and the other geological) and a large number of photographic illustrations; The latest additions to the series are: — LinlithgoTJo shire. By T. S. Muir, M.A., F.R.S.G.S. Middlesex. By G. F. Bosworth, F.R.G.S. Rutland. By G. Phillips. A list of the forty-five volumes already published will be sent on application. Volumes on the remaining counties of England, Scotland, and Wales are in an active state of pre- paration ; arrangements for a series of Irish geographies have also been made. The Realm of Ends or Pluralism and Theism. 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CONTENTS— Continued Mathematics and Physics page Radioactive Substances and Their Radiations . . . ' . . . 17 Address on Mathematics .......... '24 A Shorter Geometry together with Solid Geometr)- ..... 24 Algebra for Secondary Schools ......... ^4 Solutions of the Examples in Loney's Plane Trigonometry .... 24 Geometrical Drawing ........... 26 Botany The Genus Iris ............ 1 Herbals : Their Origin and Evolution 3 Makers of British Botany .......... 4 N.\TURE Study The Story of Our Trees .......... 5 Lessons on Soil . . . . ... . . . . . . 27 The Gateways of Knowledge .......... 27 Zoology The Vertebrate Skeleton .......... it, Psychology Heredity and Memory ........... 23 Ethnology Reports of the Cambridge Anthropological Expedition to Torres Straits, Vol. IV '17 The Tribes of Northern and Central Kordofan . . . . . . ig Geography and Travel Map Projections ............ 18 The Duab of Turkestan ........... 20 A History of Geographical Discovery ........ 22 Cambridge County Geographies ......... 23 Educational Science The Growth and Means of Training the Mental Faculty . . . , 27 Bibliography Royal Society Catalogue Subject Index, Vol. Ill 16 Scientific and Literary Journals The Modem Language Review ......... 25 The Journal of Agricultural Science ........ j-i The British Journal of Psychology ........ 25 The Journal of Hygiene .......... 25 The Journal of Genetics .......... 25 The journal of Physiology .......... 25 The Journal of Pharmacology . . . . . . . . 25 The Biochemical Journal .......... 26 Cambridge University Admissions to Peterhouse .......... 25 MENDEL'S PRINCIPLES OF HEREDITY By W. BATESON, M.A., F.R.S., V.M.H., Director of the John Innes Horticultural Institution. Third impression with ctdditions. With 3 portraits, 6 coloured plates, and 38 other illustrations. Royal 8vo. 12s. net. In the past three years the progress of Mendelian analysis has been very rapid, and the author has endeavoured in a series of brief Appendixes to acquaint the reader with the nature of the principal advances made. THE METHODS AND SCOPE OF GENETICS By W. BATESON, M.A., F.R.S., V.M.H. Crown 8vo. Is. 6d. net. " Professor Bateson tells how Mendel's law works out with the colours of certain flowers, moths, and canaries, and with colour-blindness in men and women. More than this, he describes the outlook over this field of research in a manner that will greatly interest and attract all intelligent people, for, as he rightly says, ' Mendel's clue has shown the way into a realm of nature which for surprising novelty and adventure is hardly to be excelled.' " — Morning Post HEREDITY AND MEMORY The Henry Sidgwick Memorial Lecture delivered at Newnham College, Cambridge 9 November 19 1 a By JAMES WARD, Sc.D., Professor of Mental Philosophy in the University of Cambridge, Author of The Realm of JSnds or Pluralism and Theism. Crown Svo. Paper covers, Is. net. Cloth, Is. 6d. net. It is commonly taken for granted that on this great problem — the problem of Heredity — psychology can have nothing to say. But the author has come at length to think that, provided we look at the world from what he would call a spiritualistic and not from the usual naturalistic standpoint, psychology may show us that the secret of heredity is to be found in the facts of memory. LONDON: CAMBRIDGE UNIVERSITY PRESS: FETTER LANE CONTENTS All Sights reserved FIGE A. H. Trow. Forms of Reduplication : Primary and Secondary. (With 6 Text-Figures) 313 Clifford Dobell. Some recent work on Mutation in Micro- organisms. Part II ........ • 325 K. TOYAMA. 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