696 KEPOBT— 1888. 



country in the past has accomplished great things. It has not of late, however, 

 obtained an amount of attention in any way proportionate to that devoted to 

 animal physiology. In the interests of physiological science generally, this is 

 much to be deplored ; and I believe that no one was more firmly convinced of 

 this than Mr. Darwin. Only a short time before his death, in writing to Mr. 

 Romanes on a book that he had recently been reading, he said that the author 

 had made ' a gigantic oversight in never considering plants ; these would simplify 

 the problem for him.' This goes to the root of the matter. There is, in my 

 judgment, no fundamental biological problem which is not exhibited in a simpler 

 form by plants than animals. It is possible, however, that the distaste which 

 seems to exist amongst our biologists for physiological botany may be due in some 

 measure to the extremely physical point of view from which it has been cus- 

 tomary to treat it on the Continent. It is owing in great measure to the method 

 of Mr. Darwin's own admirable researches that in this country we have been led 

 to a more excellent way. The work which has been lately done in England seems 

 to me full of the highest promise. Mr. Francis Darwin and Mr. Gardiner have 

 each in different directions shown the entirely new point of view which may be 

 obtained by treating plant phenomena as the outcome of the functional activity of 

 protoplasm. I have not the least doubt that by pursuing this path English re- 

 search will not merely place vegetable physiology, which has hitherto been too 

 much under the influence of Lamarckism, on a more rational basis, but that it will 

 also sensibly react, as it has done often before, on animal physiology. 



There is no part of the field of physiological botany which has yielded results 

 of more interest and importance than that which relates to the action of ferments 

 and fermentation ; and I could hardly give you a better illustration of the purely 

 biological method of treating it. I believe that these results, wonderful and fasci- 

 nating as they are, aflbrd but a faint indication of the range of those that are still 

 to be accomplished. The subject is one of extreme intricacy, and it is not easy to 

 speak about it briefly. To begin with, it embodies two distinct groups of phenomena 

 which have in reality very little which is essential in common. 



What are usually called ferments are perhaps the most remarkable of all 

 chemical bodies, for they have the power of eflecting very profound changes in 

 the chemical constitution of other substances, although they may be present in very 

 minute quantity ; but — and this is their most singular and characteristic property — 

 they themselves remain unchanged in the process. It may be said without hesitation 

 that the whole nutrition of both animals and plants depends on the action of fer- 

 ments. Organisms are incapable of using solid nutrient matter for the repair and 

 extension of their tissues ; this must be first brought into a soluble form before it 

 can be made available, and this change is generally brought about by the action 

 of a ferment. Animal physiology has long been familiar with the part played by 

 ferments, and it may be said that no small part of the animal economy is made 

 up of organs required either for the manufacture of ferments or for the exposure of 

 ingested food to their action. It may seem strange at first sight to speak of 

 analogous processes taking place in plants. But if must be remembered that plant 

 nutrition includes two very distinct stages. Certain parts of plants build up, as 

 everyone knows, from external inorganic materials suljstances which are available 

 for the construction of new tissues. It might be supposed that these are used up 

 as fast as they are formed. But it is not so ; the life of the plant is not a con- 

 tinuous balance of income and expenditure. On the contrary, besides the general 

 maintenance of its structure, the plant has to provide from time to time for enor- 

 mous resources to meet such exhausting demands as the renewal of foliage, the 

 production of flowers, and the subsequent maturing of fruit. 



In such cases the plant has to draw on an accumulated store of solid food which 

 has rapidly to be converted into the soluble form in which alone it is capable of 

 passing through the tissues to the seat of consumption. And I do not doubt 

 for my part that in such cases ferments are brought into play of the same kind and 

 in the same way as in the animal economy. Take such a simple case as a potato 

 tuber. This is a mass of cellular tissue, the cells of which are loaded with starch. 

 We may either dig^up the tuber and eat the starch ourselves or we may leave it in 



