Correspondence. To the Editor of the NEW PHYTOLOGIST.

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Vernon Wheeler
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1 ' 16 Correspondence. To the Editor of the NEW PHYTOLOGIST. DEAR SIR, With reference to my article in the February number of this journal on the subject of the Origin of the Perianth, I have received from Professor K. Goebel, of Munich, an intimation to the effect that I have misrepresented his views on the subject of metamorphosis in flowers by stating that they are both '* idealistic " and " resemble Goethe's type-theory." In the first place it must be said that before penning the article I had not read, as I certainly should have done. Professor Goebel's excellent "Treatise on Double Flowers" (1885), a treatise practically exhaustive in the number of interesting and valuable facts it contains. His views on the origin of the perianth are therein, and also in his " Organography of Plants" (the perusal of which I had also stupidly omitted) made plain. On page 276 of the firstmentioned work he says, when treating of the Ranunculacae : " It cannot be denied that in many cases petals have arisen from meta morphosed stamens But we have no real ground for making this a general rule." Another passage runs thus : " As in this case [Equisetum ] certainly in many others, perianth and corolla-formation takes place through transformation of the leafrudiments occurring in the neighbourhood of the flower." The calyx he appears to regard with Prantl, as of bracteal origin. I take this occasion to make every apology to Professor Goebel for introducing his name in connexion with the subject without a discussion of those important views which most directly bear thereon. But the remarks with which Professor Goebel's name was introduced, had reference to his theory on the morphology of the foliar organs of the flower expressed in an earlier work of his, the '* Vergleichende Untersuchungen," and which may be stated thus: " that any foliar organ of a flower, whether sepal, petal, stamen, or carpel, is a modification or transformation of a rudiment, which itself is always of the nature of a foliage-leaf." Goebel's view may, in other words, at least, as I understand it, be stated thus : "that the foliage-leaf is the morphological type from which all other kinds of foliar organs are derived modifications." This view, put forward without any apparent evidence to support or give reason for it,'\i is safe, as it appears to me, because correct, to describe a.s " idealistic." Is it less so than that of Goethe, who merely held that all foliar organs of the plant are modifications of the " leaf," by which he probably meant the foliage leaf? Or, if by type-leaf was meant a purely ideal entity, his view would, in my opinion, be much nearer the truth and might be merely a statement in concrete, though misleading, language of the fact that all foliar organs of the plant are modifications of a primeval ancestral foliar organ now no longer existing, which I for one would be the last to deny. The views of both Goethe and Goebel must be regarded as idealistic for the simple reason that they possess a purely subjective value, being unsupported by the necessary buttress of scientific argument or evidence. On the other hand, Celakovsky's view regarding the ancestral type of the foliar organs, which is ba.sed on a definite well-thought-out line of scientific argument and theory, is clearly the opposite of idealistic.

$Correspondence. \ 17 In the last (March) number of this journal, (page 66). Dr.$

2 Correspondence. \ 17 In the last (March) number of this journal, (page 66). Dr. Rendle, in a very interesting article on the subject of the origin of the perianth (which I am glad that my own writing should have had the effect of evoking) questions at several points the tenableness of my position. In reference to my statement that sporophylls preceded in time all other kinds of leaves and that the latter must therefore have been derived from the former, the writer says: " this need not imply the derivation of the perianth from sporophylls in the highest group of plants." For " the differentiation of foliage-leaf and sporophyll was an established fact before the evolution of the Angiosperm and there is therefore no a. priori reason for deriving the floral envelopes in the latter group from sporophylls." Dr. Rendle here refers to the direct and immediate origin of vegetative foliar organs, such as petals and sepals; for the possibility is not excluded that, at any rate, in some cases, the vegetative foliar organs may have taken, as it were, a step backward and become once more approximated to the fertile region of the axis (from which they were originally derived) in the form of a calyx or even of a corolla. As regards flowering plants generally this theory, in view of all the important and striking facts and arguments which have been brought under my notice, appears to possess but little plausibility as compared with the theory I have supported. Again, the writer finds it " difficult to accept the statement in its entirety" that calyx and corolla have both sprung from the androecium, adducing the argument that the most primitive flowers are unisexual and " have presumably not been derived from an hermaphrodite type, yet we find in the female, as well as in the male, instances of a well-defined perianth, which in the case of the female could not have originated from an andicecium. Hence the oiigin of perianth from andrcecium cannot have been universal." Now, I fail entirely to see why the most primitive fiowers should not in certain characters be more advanced and modified than those of plants standing higher in the scale. The complex massing of the flowers in catkins is surely such a highly modified character. So is it also with their striking diclinous arrangements. On the general principle, to which I firmly adhere, that the undifferentiated must precede in time the differentiated, and union always precede disunion, it follows that in all departments of the vegetable kingdom, the separation of the sexes must have been a secondary process, and hermaphroditism in all cases represent a more primitive state of affairs. Hence it follows that the perianth of a female flower could have been quite naturally derived from the stamens in the early hermaphrodite days, and may in some cases represent these stamens in their modified vegetative form. The whole matter is elaborated by Celakovsky in his work on the Flower. As to the case of the glands in the Willow-flower, if these represent a reduced perianth, then they must be regarded as of staminal origin; the fact that they are more numerous in the male than in the female flowers need not necessarily have, either one way or the other, any bearing on the question at issue, being probably due to quite other causes. Nor do I see, in reference to the case of the Betuleae mentioned, why the female should be expected to exhibit necessarily a similarity of arrangement to the male flower; for the hermaphrodite flower might, surely, have become modified subsequently to the loss of its androecium?

3 118 Correspondence. In his discussion as to the relation between the perianth and the bracteoles in the Coryleae and Betuleae, the writer seems almost driven into a corner in his attempt to account for the origin of the perianth in the former group. Finding a correlation in their protective function to exist between the bracteoles and the perianth he feels bound to associate the two sets of organs together in their origin, and, discovering the presence of both perianth and bracteoles in the female flowers of the Coryleae, he concludes that " if it is not possible to regard the perianth as a new foliar organ sui generis we must seek its origin in additional bracteoles." This mode of origin of the perianth by the intercalation ex nihilo of additional foliar organs between those already present at different levels of the axis would be,.to my mind, a quite unnatural and impossible one. For whence did these extra bracteoles arrive on the scene? Why not recognise the far more natural, and, to my mind, far less forced method of derivation by means of sterilisation of the stamens in the ancestral hermaphrodite flower? In treating of the Fagaceae, the writer remarks : " In the male flower the numbers in the two series, perianth and androecium, vary in the same direction, an increase in the number of perianth-leaves is associated with an increase, not with a decrease, in the number of the stamens." Here he obviously refers to the case, mentioned by him, of Nothofagus obliqua, in whose flowers both stamens and perianthsegments exist to the number of 30 40, which is in contrast to other genera, in which they are often only from 4 7 in number. I regard, however, with Celakovsky, such forms as Nothofagus, possessing a large number of stamens, as primitive, while the 4 7 stamens and perianth-segments of other genera must be regarded as the result of reduction from the larger number; hence it is clear that in a case such as Nothofagus where an increase in the number of perianthsegments obtains, there can be no possible question of an increase in the number of stamens; on the contrary, I hold that very considerable decrease in their number must have taken place in order to provide the numerous perianth leaves which are present. With regard to the Juglandaceae, Dr. Rendle says: " There is a strong suggestion of homology of perianth and bracteoles, and it is difficult to imagine a different origin for the two sets of leaves." This is precisely my own view, and I may as well here state once for all my firm conviction that all foliar organs (even such curious, independent-looking structures as the cup substending the androecium in the Poplar) which are in close proximity to the flower, have, within a comparatively recent period, been derived from sporophylls. Dr. Rendle himself discovers and acknowledges the production of unisexual flowers by abortion of the stamens in the hermaphrodite flowers of the Saurureae. But he remarks that: " Abortion of the stamens... never results in the formation of a perianth." Abortion of any organ could surely hardly result in anything but its annihilation! And the absence of a perianth is clearly correlated with the development of the bract as a protective structure for the androecium and ovary. In the case of the Ulmaceae, &c., the difficulty raised may be easily and quite naturally surmounted by assuming, as in the case of Primula, the abortion of an outer whorl of stamens. Turning now to the point raised in the penultimate paragraph of

4 The London Botanical Society. 119 Dr. Rendle's paper: I merely regard the petaloid calyx in flowers containing nectaries as being, for the reasons adduced, more primitive than the green calyx in ilowers possessing a coloured corolla and in these latter only. It is, of course, more recent than the early wind-fertilised flowers. I regard the green calyx of the ordinary entomophilous flower of the Dicotyledons, &c., as having probably passed through the petaloid stage. The " absence of definiteness in the limitation of distinct series " amongst foliar organs arranged along a spiral line on the axis affords to my own mind a good piece of evidence for the common origin of all the said foliar organs, and this, I hold, must lie in the sporophylls. Finally, I would refer to Celakovsky's works for more detailed illustration, by means of concrete examples, of the process of origin of the perianth of flowers. And I would add that where, as in the articles of Dr. Rendle and myself, the points of view radically diflfer, it seems unlikely that any amount of discussion will bring about an agreement. April 12th, Yours, etc., W. C. WORSDELL. THE LONDON BOTANICAL SOCIETY. AT the meeting on Tuesday, March 17th, Mr. S. Hastings shewed a long series of extremely successful habit-photographs of British Fungi, many ol which were considerably magnified. The greater number were of Agarics and their allies, but Ihcre were also several Ascomycetes in the collection. Geaster and Nidularia (much magnified) were particularly beautiful examples of the photographer's skill. It is to be hoped that Mr. Hastings may see his way to publish a set of these photographs, since they are some of the best we have seen and really good habit-pictures of plants are always valuable. Professor J. Reynolds Green gave a most interesting and lucid account of his recent work on the Germination of Fatty Seeds. The time is not yet ripe, however, to publish any details of the results. At the meeting on Tuesday, May 12th, the Secretary, Professor Farmer, gave an account of the work he has been doing, in conjunction with Mr. J. E. S. Moore and Miss Digby, on the cytological features connected with apogamy in fern prothalli. It bas been successfully shewn that the nucleus of one prothallus-cell passes through the cell-wall where it presumably fuses with the nucleus of the neighbouring cell, from which the apogamous growth originates. The number of chromosomes in the nuclei before fusion is roughly forty.

Flower Morphology. Flower Structure

Flower Morphology. Flower Structure wrong 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 right 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 score 100 98.8 97.6 96.4 95.2 94.0 92.9 91.7 90.5 89.3 88.1 86.9 85.7 84.5