PRESIDENTIAL ADDRESS. 705 



stages in the life-history as individuals, their development presenting the same 

 general problems as a plant of, say, Fuciis or Enteromorpha, where there is no 

 alternation of generations. How is the morphologist to regard this process of 

 individual development ? 



In the first place we seem forced to regard the specific distinctness as hold- 

 ing for the germ as well as the resulting mature plant, however the relation 

 between the germ-cell and the characters of the developed organism is to be 

 explained. We start thus with a conception of specific substance,^ leaving it 

 quite an open question on what the specific nature depends. This enables us 

 to state the problem of development freed from all considerations of the ultimate 

 uses of the developed structure. The course of development to the adult 

 condition can be looked upon as the manifestation of the properties of the 

 specific substance under certain conditions. This decides our attitude as 

 morphologists to the functions of the plant and to teleology. Function does not 

 concern us except in so far as it is found to enter as a causal factor into the 

 process of development. Similarly until purpose can be shown to be effective as 

 a causal factor it is merely an unfortunate expression for the result attained. 



Let me remind you also that the individual plant, whether it be unicellular, 

 ca-iiocytic or multicellular, may behave as a whole at all stages of its develop- 

 ment. We see this, for instance, in the germination of Qidofjonium, in the 

 germination ami subsequent strengthening of the basal region in Fucua or 

 Laminaria, in the moss-plant or fern-plant, or in a dicotyledonous tree. A system 

 of relations is evident in the plant, expressed in the polarity and the mutual 

 influences of the main axis and lateral branches, as well as in the influences 

 exerted on the basal region by the distant growing parts. We thus recognise, 

 in its most general form, the correlation of parts, a concept of proved value 

 in botany. 



To some the expression of the observed facts in this way may appear 

 perilously mystical. I do not think so myself. It is true that the nature of 

 the specific substance and of the system of relations is unknown to us, but it is 

 regarded as a subject for scientific inquiry and further explanation. To 

 recognise fully the complexity of the substance of the plant is not, however, 

 a step towards neo-vitalism, but is perhaps our best safeguard against the 

 dangers of this. 



The wholeness of the individual, together with important phenomena of 

 regeneration, has suggested the conclusion that something other than physico- 

 chemical or mechanical laws are concerned in the development of the 

 organism. To this something Driesch applies the name entelechy. Without 

 discussing the vitalistic philosophy of the organism, or other modern 

 phases of philosophic thought that treat life as an entity, it seems 

 worth while to point out that they are based mainly on the consideration 

 of animal development. It would be interesting to inquire into the 

 difficulties that are met with in applying such views to plants, where 

 regeneration in one form or another is the rule rather than the exception and 

 often does not lead to restitution of the individual. Causal morphology can 

 recognise phenomena of development and of the individual, which are at present 

 beyond physico-chemical explanation, and try to attack them by any methods of 

 investigation that seem practicable, without begging the main question at the 

 outset and then proceeding deductively. To assume any special inner director of 

 development, be it entelechy or vital force, is to cut the knot that may ultimately 

 be untied. 



The previous experience of botany in the time of nature-philosophy may well 

 mqke us cautious of solving our difficulties by the help of any new biological 

 }ihilosophy. On the other hand, co-operation between biology and philosophic 

 thought is highly desirable. In this connection I should like to refer to an idea 

 contained in Professor Alexander's paper on the Basis of Realism.' He 



* The more general concept of specific substance, which avoids hypcthesc= 

 of heredity, seems preferable for our purpose to that of idioplasm or even of 

 specific cell, since it leaves open the possibility of some properties of the plant 

 being generalised in the protoplasm and not to be explained by the mutual 

 relation of cells : it al.^o covers the ease of coenocytic plants. 



" Royal British Academy, Jan. 28, 1914, p. 12. 

 1915. Z a 



