Supplement to "Nature," December 23, 1922 





Pasteur and Preventive Medicine. 



By Prof. J. C. G. 



PASTEUR'S life-work is a finished symphony, a 

 science in miniature, and it is, perhaps, not 

 generally appreciated that the Master was well advanced 

 in years when he commenced the final chapter which 

 witnessed that remarkable series of experiments in 

 prophylactic immunisation which culminated in his 

 dramatically successful attack on rabies. This crown- 

 ing victory over a dreaded scourge was rendered possible 

 by Pasteur's profound faith in the immunising powers 

 of attenuated viruses — a faith which his previous 

 experience with fowl cholera, swine erysipelas, and 

 anthrax had but strengthened. It was in essence the 

 faith of Jenner. 



Pasteur commenced the final chapter of his life, 

 which he devoted to preventive medicine, as the com- 

 plete comparative pathologist and he remained one to 

 the end. It is true that fowl cholera and anthrax were 

 among the few infections of which the microbic agents 

 were at least known, though meagrely studied. The 

 great chain of discoveries in the causation of human 

 infections dating from the early 'eighties, and inspired by 

 the genius of Koch's pure culture studies, was yet un- 

 forged, and in that work Pasteur and his school took 

 little share. To Pasteur the accurate knowledge of a 

 virus was simply a stimulus to attack the disease on the 

 preventive side, but neither to him nor to his great 

 contemporary Lister was this stimulus an essential 

 one. If a virus could be demonstrated and cultivated 

 outside the body, so much the better. Attenua- 

 tion was all the simpler. So when he came to 

 rabies, ignorance of the actual virus did not deter him 

 from the attempt to attenuate its virulence by an 

 ingenious method of his own and to render it amenable 

 for prophylactic use. His demonstration of the pre- 

 dilection of rabies virus for brain and spinal cord 

 supplied the key that opened the secret door. 



Ledingham, F.R.S. 



It is fortunate, perhaps, that Pasteur's activities 

 in preventive medicine were solely concerned with 

 veterinary disease. There he had full scope for animal 

 experiment on the large scale and he could assess at will 

 the value of a prophylactic measure under controlled 

 experimental conditions. That day at the farm of 

 Pouilly-le-Fort when he arrived to find the vaccinated 

 sheepand cattlealive and well, while all the unvaccinated 

 controls were dead or dying of anthrax, must have been 

 a glorious date in a calendar that held many such. But 

 all systems of immunisation, whether in man or animal, 

 when brought to the test of the field experiment, reveal 

 their relative value, and Pasteur's essays have been no 

 exception to the rule. His guiding principles in im- 

 munisation have, however, easily stood the light of 

 fifty years and never were they more keenly debated 

 than to-day, when the factors that control the vagaries 

 of bacterial virulence are just beginning to be under- 

 stood. Pasteur was, perhaps unconsciously, the first 

 exponent of bacterial variation, a field of work that 

 exercises many minds to-day and bids fair to yield a 

 rich harvest. Attenuation was secured by Pasteur in 

 several different ways, in fowl cholera by prolonged 

 incubation of the virus, in swine erysipelas by passage 

 through another animal species, and in anthrax by 

 altering the temperature of incubation. 



What amount of success has been achieved since then 

 in prophylaxis against human infections is due to the 

 substitution of the killed for the attenuated live virus — 

 certainly an expedient, but very possibly a retrograde, 

 modification of Pasteur's principle. The solution of 

 the mysteries of attenuation, to which renewed study is 

 being devoted, may yet open up new vistas in pro- 

 phylaxis and in serum-therapy, but to Pasteur's pioneer 

 work in this field, preventive medicine must for ever 

 pay homage. 



Pasteur in Crystallography. 

 By Dr. A. E. H. Tutton, F.R.S. 



IT is very rare indeed that a scientific man of our 

 time is equally distinguished for his researches 

 in both the great fields of natural science, the chemico- 

 physical and the biological, yet this is true of Louis 

 Pasteur. His fame as a chemical crystallographer was 

 assured for all time by his brilliant discovery, as a young 

 man of twenty-six in the year 1848, of the true nature 

 of tartaric acid, by his measurement of the crystals of 

 the two optically active varieties, and by his revelation 

 of the connexion between right- and left-handedness 

 of crystalline form (enantiomorphism) and optical 



activity. This particularly interesting property of 

 rotating the plane of polarisation of a ray of polarised 

 light has been said by Prof. Percy Frankland to be 

 " the distinctive seal of nobleness exhibited by the 

 aristocracy of chemical compounds." The distinction 

 achieved by Pasteur in the biological world, great as 

 it is, rendering his name a household word among us 

 and one to be blessed by generations yet to come, 

 is thus at least equalled by his pioneer services to 

 crystallography. 



It is somewhat remarkable that Mitscherlich in the 



