NA TURE 



149 



ORGANOGRAPHY AND ITS RELATIONS TO 



BIOLOGICAL PROBLEMS, 

 Organographie der Pflamen, insbesondere der Archegoni- 



aten und Santenpflanzen. Von Dr. K, Goebel. 



Zweiter Theil. 2 Heft : Pteridophyta und Samen- 



pflanzen. Mit 173 abbild. im text. Pp. xvi + 385 



to 648. (Jena : Gustav Fischer, 1900.) 

 'X* HE volume before us forms a further instalment of 

 the large treatise on the organography of plants 

 upon which Prof. Goebel is engaged. The part just 

 published deals with the vegetative organs of the flowering 

 plants, and, in a lesser degree, with the sporophyte and 

 gametophyte of the vascular cryptogams. 



It is needless to remark that the book teems with 

 information, and, as might be anticipated, the author has 

 drawn largely, for purposes of illustration, on the rich 

 stores of material collected by him during his travels in 

 various parts of the world. It is possible, however, that 

 a layman on reading the book would arrive at the con- 

 clusion that in this particular field (of organography) 

 other botanists had displayed far less activity than might 

 have been expected from them, and would thus give them 

 less credit than a closer acquaintance with either litera- 

 ture or the class-room would show they deserved. 



The plan of the book is partly morphological, but 

 woven into the morphological warp there is also the 

 biological woof, and the author has emphasised, in a way 

 which few could have done so well and, perhaps, no one 

 more fully, the interdependence of these two groups of 

 factors which so largely determine the actual form of 

 existing plants. Goebel has long been known as an 

 exponent of the concrete, and throughout the treatise one 

 constantly finds traces of his antagonism towards that 

 idealism into which, if the function of an organ be 

 neglected, the morphologist is even still apt to stray. 



Whilst tracing the various modifications which a given 

 structure — e.g. a root — may exhibit in diflFerent plants, or 

 in different parts of the same individual, the author con- 

 stantly insists that these are, in fact, due to a deviation 

 from the ordinary course of growth which commonly 

 culminates in the formation of a normal root. Similarly, 

 though it is more difficult to prove the point owing to their 

 greater variety (depending on their more varied environ- 

 ment), the author argues that the modified leaf structures, 

 scales, thorns, and so on, are brought about by causes 

 acting on the developing primordium of what would, if 

 unchecked, become a foliage-leaf. This latter is for 

 Goebel the actual typical leaf, and from it, by an exagger- 

 ation or attenuation of parts which are already recog- 

 nisable during its earlier stages, the modification occur- 

 ring in any given example proceeds. He strenuously 

 opposes the view advocated by some writers that the leaf- 

 primordium is an indifferent structure, and regards it as 

 normally destined to give rise to an ordinary leaf. He 

 has himself, more, perhaps, than any one else, shown how 

 easy it is in some cases to interfere with those causes or 

 sequences of events leading to the modification of such 

 an organ, and thereby to effect a reversion in favour of 

 the more primitive organ to take place. Probably most 

 NO. 1624, VOL. 63] 



people would be inclined to admit that, on the whole, the 

 main lines of evidence go to prove that the obvious 

 assumption made by Goebel in this connection with 

 regard to the original character of the organ is a valid 

 one. 



It must, however, be confessed, and any one at all 

 conversant with contemporary literature will recognise 

 the fact, that there exists some danger of attaching a one- 

 sided importance to the readiness with which organisms 

 adapt themselves to the exigencies of a changed environ- 

 ment. For the response in form and structure is often 

 so direct and obviously purposeful that more stress is apt 

 to be laid on the stimulus itself than on the nature of the 

 body to be stimulated, with its complex and varied me- 

 chanism, and there are some who have gone so far as to 

 read into this purposeful variation an immediate explana- 

 tion of the formation of new or incipient varieties ; as 

 though the real fact which mainly stands in need of 

 analysis were not the very one constituted by this self- 

 same purposeful character of the response. And indeed 

 it would appear, upon reflection, that this form of response 

 is itself the result of the operation of natural selection 

 which has acted by eliminating the chance of leaving 

 descendants from all those competitors in whom the re- 

 action to a given set of conditions happened to fall short 

 of a certain standard of perfection. It need not neces- 

 sarily follow that all must have varied in an identical 

 manner, but those that failed to comply, by some suitable 

 change or another, with the requirements imposed by the 

 new conditions, must inevitably be ousted by their more 

 gifted rivals, and if these assumed changing conditions 

 periodically recur, then the process of elimination will 

 result in those only being left in which the power to 

 respond accurately (/.^. purposefully), and it maybe rapidly, 

 to a particular change has been best developed and 

 cultivated. 



It is obvious that a similar result, mutatis mutandis^ 

 would follow if a complex variety of stimuli be substi- 

 tuted for the simple case touched on above, and thus a 

 protoplasmic mechanism is gradually selected and per- 

 fected which, when stimulated by any means to which 

 there can be a response at all, will reply by the corre- 

 sponding reaction normal for that species or race. But 

 though normal in kind for the race, its degree will vary 

 in different individuals, as any one can readily prove by 

 direct observation. Hence it at once becomes subject to 

 the operation of natural selection. Naturally, so long as 

 a particular stimulus is absent the corresponding response, 

 however well tuned and ready, will remain in abeyance 

 as a latent potentiality. 



A study of plants reveals numerous examples of this. 

 Amphibious plants frequently are able to assume alterna- 

 tive characters, respectively fitted for either a terrestrial 

 or an aquatic habit, and it depends entirely on the nature 

 of the stimulus arising from the environment as to which 

 of the two types of structure shall appear. Such plants, 

 during their species-life, have been repeatedly exposed 

 to vicissitudes of a somewhat extreme character, and the 

 latent ability to change so as to adapt themselves more 

 fully to altered circumstances must have played no un- 

 important part in securing the survival of their race. 

 Many other examples could be quoted to show how im- 

 portant for stationary beings like plants is the possession 



H 



