TRANSACTIONS OF SECTION D. 701 



Here we have an example of a disease wliicb, though having a well-marked 

 zymotic character, is comparatively harmless. In Anthrax, which is known to be 

 due to Bacillus anthracis, we have one which is, on the contrary, extremely fatal. 

 I need not enter into the details. It is sufficient to say that there is reason to 

 helieve that the Bacillus produces, as one of those by-products of protoplasmic 

 destruction to which I have already alluded, a most virulent poison. I3ut the 

 remarkable thing is that this Bacillus, wliich can be cultivated externally to the 

 hody, if kept at a heightened temperature, can be attenuated in its virulence. 

 It drops, in fact, the excretion of the poison. It is then found that, if injected 

 into the blood, it does no mischief, and, what is more extraordinary, if the Bacillus 

 in its most lethal form is subsequently introduced, it too has lost its power. The 

 explanation of the immunity in this case is entirely different to that which was 

 suggested by a consideration of the facts of relapsing fever. The researches of 

 Metschnikotf have led to the hypothesis that in the present case the white blood- 

 corpuscles destroy the Bacillus. When they first come into contact with these in 

 their virulent form they are unable to touch them. But if they have been educated 

 by first having presented to them the attenuated form, they find no difficulty in 

 grappling with the malignant. This is a very remarkable view. I should not have 

 put it before you had there not been solid reasons for regarding the idea of the 

 education cf protoplasm with scientific respect. The plasoiodia of the myxomy- 

 cetes, which consist of naked protoplasm, are known to become habituated to food 

 which they at first reject, and the researches of Beyerinck on the disease known as 

 ' gumming ' in plants have apparently shown that healthy cells may be taught, as it 

 were, to produce a ferment which otherwise they would not excrete. 



If Metschnikoft''s theory be true, we have a rational explanation of vaccination 

 and of preventive inoculation generally. It is probably, however, not the only 

 explanation. And the theory of the inhibitive action upon itself of the products of 

 the ferment-organism's own activity is still being made the basis of experiment. 

 In fact, the most recent results point to the possibility of obtaining protection by 

 injecting into the blood substances artificially obtained entirely independent of the 

 organisms whose development they inhibit. 



It is impossible for me to touch on these important matters at any greater length, 

 but I doubt if the theory of fermentation, as applied to the diseases of organisms, 

 has as yet more than opened its first page. It seems to me possible that, besides 

 the rational explanation of zymotic diseases, it may throw light on others where, 

 owing to abnormal conditions, the organism, as in the case of B^rard's plums, is 

 itself the agent in its own fermentative processes. 



And now I must conclude. I have led you, I am afraid, a too lengthy and 

 varied a journey in the field of botanical study. But to sum up my argument. I 

 believe I have shown you that at the bottom of every great branch of biological 

 inquiry it has never been possible to neglect the study of plants ; nay, more, that 

 the study of plant-life has generally given the key to the true course of investiga- 

 tion. Whether you take the problems of geographical distribution, the most 

 obscure points in the theory of organic evolution, or the innermost secrets of vital 

 phenomena, whether in health or disease, not to consider plants is still, in the words 

 of Mr. Darwin, ' a gigantic oversight, for these would simplify the problem.' 



The following Reports and Papers were read : — 



1. Report of the Committee for exploring the Flora of the Bahamas. 



See Reports, p. 361. 



2. Second Report of the Committee for taking 'steps for the establishment of 



a Botanical Station at Peradeniya, Ceylon. — See Reports, p. 421. 



3. Report of the Committee for continuing the preparation of a Report on our 



present Jcnotvledge of ihe Flora of China. — See Reports, p. 420. 



