47 8 



NATURE 



{Sept. 



1888 



serious study of botany in the laboratory will be in time better 

 cared for. I do not hesitate to claim for it a position of the 

 greatest importance in ordinary scientific education. All the 

 essential phenomena of living organisms can be readily demon- 

 strated upon plants. The necessary appliances are not so 

 costly, and the work of the class room is free from many diffi- 

 culties with which the student of the animal side of biology has 

 to contend. 



Those, however, who have seriously devoted themselves to the 

 pursuit of either morphological or physiological botany need not 

 now be wholly at a loss. The splendid laboratory on Plymouth 

 Sound, the erection of which we owe to the energy and en- 

 thusiasm of Prof. Ray Lankester, is open to botanists as well as 

 to zoologists, and affords every opportunity for the investigation 

 of marine plants, in which little of late years has been done in 

 this country. At Kew we owe to private munificence a com- 

 modious laboratory in which much excellent work has already 

 been done. And this Association has made a small grant in 

 aid of the establishment of a laboratory in the Royal Botanic 

 Garden at Peradeniya, in Ceylon. It may be hoped that this 

 will afford facilities for work of the same kind as has yielded 

 Dr. Treub such a rich harvest of results in the Buitenzorg 

 Botanic Garden in Java. 



Physiological botany, as I have already pointed out, is a field 

 in which this 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 con- 

 vinced 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 customary 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 

 Daiwin 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 d6ubt that by pur- 

 suing this path English research 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 tbat these results, wonderful 

 and fascinating as they are, afford 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 re- 

 markable of all chemical bodies, for they have the power of effect- 

 ing very profound changes in the chemical constitution of other 

 substances, although they may be present in very minute quantity ; 

 but, and this is their mo>t 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 ferments. Organisms are 

 incapable of using sdIIcI 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 it must be remembered that plant nutrition 

 includes two very distinct stages. Certain parts of plants build 

 up, as everyone knows, from external inorganic materials sub- 

 stances 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 continuous 

 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 enormous 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 the ground, in which case it will be consumed 

 in providing material for the growth of a potato-plant next year. 

 But the processes by which the insoluble starch is made avail- 

 able for nutrition are, I cannot doubt, closely similar in either 

 case. 



When we inquire further about these mysterious and all- 

 important bodies, the answer we can give is extremely inade- 

 quate. It is very difficult to obtain them in amount sufficient 

 for analysis, or in a state of purity. We know, however, that they 

 are closely allied to albuminoids, and contain nitrogen in vary- 

 ing proportion. Papain, which is a vegetable ferment derived 

 from the fruit of the papaw, and capable of digesting most 

 animal albuminoids, is said to have the same ultimate composi- 

 tion as the pancreatic ferment and as peptones, bodies closely 

 allied to proteids ; the properties of all three bodies are, how- 

 ever, very different. It seems clear, nevertheless, that ferments 

 must be closely allied to proteids, and, like these bodies, they 

 are, no doubt, directly derived from protoplasm. 



I need not remind you that, unlike other constituents of plant 

 tissues, protoplasm, as a condition of its vitality, is in a constant 

 state of molecular activity. The maintenance of this activity 

 involves the supply of energy, and this is partly derived from 

 the waste of its own substance. This "self-decomposition " of 

 the protoplasm liberates energy, and in doing so gives rise to a 

 number of more stable bodies than protoplasm. Some of these 

 are used up again in nutrition ; others are thrown aside, and are 

 never drawn again into the inner circle of vital processes. In 

 the animal organism, where the strictest economy of bulk is a 

 paramount necessity, they are promptly got rid of by the pro- 

 cess of excretion. In the vegetable economy these residual pro- 

 ducts usually remain. And it is for this reason, I may point 

 out, that the study of the chemistry of plant nutrition appears 

 to me of such immense importance. The record of chemical 

 change is so much more carefully preserved ; and the prob- 

 ability of our being able to trace the course it has followed is 

 consequently far more likely to be attended with success. 



This preservation in the plant of the residual by-products of 

 protoplasmic activity no doubt accounts for the circumstance 

 which otherwise is extremely perplexing — the profusion of sub- 

 stances which we meet with in the vegetable kingdom to which 

 it is hard to attribute any useful purpose. It seems probable 

 that ferments, in a great many cases, belong to the same cate- 

 gory. I imagine that it is in some degree accidental that some 

 of them have been made use of, and thus the plant has been 

 able to temporarily lock up accumulations of food to be drawn 

 upon in future phases of its life with the certainty that they 

 would be available. Without the ferments the key of the 

 storehouse would be lost irretrievably. 



Plants, moreover, are now known to possess ferments, and 

 the number will doubtless increase, to which it is difficult t< 

 attribute any useful function. Papain, to which I have already 

 alluded, abounds in the papaw, but it is not easy to assign to 

 it any definite function ; still less is it easy, on teleological 

 grounds, to account for the rennet ferment contained in tl 

 fruits of an Indian plant, Withania coagu'ans, and admirably 

 investigated by Mr. Sheridan Lea. 



Having dwelt so far on the action of ferments, we may now 

 turn to fermentation, and that other kind of change in organic 

 matter called "putrefaction," which is known to be closely 

 allied to fermen'ation. Ferments and fermentation, as I have 



