March, 1910,1 



241 



Miscellaneous. 



It will doubtless have occurred to 

 many of yon to ask the question, How 

 is it, if the air contains floating in it the 

 dried spores of multitudinous micro- 

 organisms which only need a suitable 

 medium for their development and in- 

 crease, how is it that they do not obtain 

 a lodgement in the healthy animal body, 

 which one would think offers all the 

 conditions necessary to their growth ? 

 It can easily be shown that the air we 

 breathe, the water we drink, the food 

 we eat, everything that we touch, 

 swarms with these microscopic creatures; 

 that they enter our lungs, that they 

 germinate in our skin, that they occur 

 in countless numbers in our alimentary 

 canals, in short, that they are found 

 everywhere on our body surfaces. How 

 is it that they do not increase and turn 

 our organs into a seething mass of 

 putrefying corruption ? One would 

 expect that even if the skin and the 

 membrane bounding the internal organs 

 to which they obtain entrance incurred 

 the slightest lesion, even a pin-prick, 

 that they would have been able to enter. 

 We know that after death they at once 

 obtain complete dominion, and we there- 

 fore infer that in life there must be some 

 protective mechanism in the body 

 capable of dealing with them. 



The discovery that there is such a 

 mechanism was made in the early 

 eighties by the distinguished Russian 

 zoologist, Elias Metschnikoff, though 

 the need of its existence was not re- 

 cognised by biologists in general until 

 later. The result of this was that 

 his remarkable discoveries were at 

 first pooh-poohed and discredited by 

 many, but ultimately they gained aq- 

 ceptance, and their further development 

 in his own hand and that of others has 

 wrought a revolution in the art of pre- 

 ventive medicine. 



The mechanism consists of the small 

 amoeboid cells found in the blood> 

 lymph, and body fluids generally, and 

 called leucocytes, or white blood cor- 

 puscles. Though long known to exist, 

 very little has been ascertained as to 

 their function until Metschnikoff, work- 

 ing at such remote subjects as the 

 embyrology of sponges, the structure 

 and digestion of polyps, the blood of 

 water-fleas, realised that these small 

 amceba-like cells, which exist in all 

 organisms, actually swallow, digest, and 

 so destioy small foreign bodies which 

 have invaded the organisms. He called 

 them the phagocytes, and all his subse- 

 quent work has been directed to the 

 elucidation of their mode of action. 



It is to Metschnikoff's work, prompt- 

 ed solely by the scientific spirit, that 



we owe our knowledge of phagocytosis 

 and the great theory of immunity which 

 has proceeded from it. It is impossible 

 at the present moment to estimate fully 

 the value to man of Metschnikoff's dis- 

 coveries. Suffice it to say that they 

 have already led to import practical 

 results, and have revolutionised treat- 

 ment. 



I must now turn for a moment to 

 another subject of the greatest im- 

 portance to mankind, and one which 

 has been brought into notice by the 

 researches, perfectly useless so far as 

 our material welfare is concerned, which 

 were undertaken with the view of 

 elucidating the great question of organic 

 evolution. I refer to the study of 

 genetics, which deals with the question 

 mainly of the transmission of the pro- 

 perties of the organism; but it deals 

 with even a larger subject than that. It 

 looks into and tries to determine the 

 laws which govern the origin of the 

 characters of individuals, whether plants 

 or animals, whether those characters 

 have been acquired by inheritance or 

 in some other way. The subject is Df 

 the .utmost interest and practical im- 

 portance to man from three points of 

 view. It has a bearing on philosophy of 

 a most important and far-reaching kind 

 through the theory of organic evolution. 

 That theory largely depends for its 

 proof upon the science of genetics. 

 Secondly, it has a most important 

 bearing upon practical questions affect- 

 ing breeders of animals and raisers of 

 plants, and also upon man himself in con- 

 nection with practical legislation. This 

 brings me to the chird point, in which 

 this subject specially appeals to us, and 

 that is what I may call its bearing upon 

 ethics. This is, of course, closely con- 

 nected with the last. 



We are contstantly confronted with 

 questions in which we have to think, not 

 only of the advantage and happiness of 

 those alive at the present moment, but 

 also of those not yet born who will suc- 

 ceed us on the earth. The decision of 

 these questions is one of the most im- 

 portant and burning subjects which can 

 be put before us. They often crop up in 

 legislation, and yet we are quite un- 

 able to answer them because of the very 

 little knowledge we possess of the laws 

 which govern the transmission of charac- 

 ters from generation to generation. 



The interests of future generations 

 often appear to be in conflict with the 

 immediate pleasure and happiness of 

 the living, and we are confronted with 

 the question whether we ought to give 

 way to our own humane and benevolent 

 feelings, or whether we ought to set 



