The transmutation of bacteria - PDF book by Samuel Gurney-Dixon

The transmutation of bacteria

The transmutation of bacteria


This essay is based upon notes and observations which I collected previous to the year 1913. It was only partly written when, in August 1914, I proceeded on active service. I was able, however, to complete it in the following summer while serving with a Field Ambulance in France, and in the autumn of the same year (1915) I submitted it in the form of a Dissertation for the degree of M.D. at the University of Cambridge. 

The difficulties in carrying out work of this character while serving at the Front — remote from libraries and amidst " alarms and excursions " which break up one's scanty leisure — are sufficiently obvious and I trust may excuse some of its defects. Some valuable materials which I had hoped to utilise, including chapters on Viability and Agglutination Reactions, were buried by a shell explosion and could not be replaced. 

The claims of Army work have also precluded any attempt on ray part to bring the work up to date by reference to papers published since the beginning of the war. I particularly regret having learnt too late to include any mention of it in the following pages of the valuable research carried out by Dr Thiele and Dr Embleton on the part played by the body ferments in the pathogenicity of bacteria. 

Though I have endeavoured to suppress all irrelevant matter, I am only too conscious of the discursiveness of this essay. The topic is one of absorbing interest and at every step one is tempted to digress. In the words of Dante, which I have quoted on the title page, "The novelty must be my excuse if my pen has wandered at all."

Some contents:

THE SCOPE OF THE ENQUIRY
Definition of Terms. Transmutation is not evolution — evolution in bacteria — its stages. Natural variation — "Spontaneous" and "impressed." Variation is easily studied in bacteria — unicellular organisms — method of generation — rapidity of generation — environment easily modified. Natural selection. Artificial selection. "Transmutation of Species" is apparently contradictory — meaning of "species" — based on characters. Arbitrary nature of the distinction between species — illustrated by streptococci — classified according to food- stuff's and haemolytic power, adhesiveness, staining, cultural characters, virulence and pathogenicity, agglutination, fermenting power. "Species" not a rigid term.

CHAPTER II CONDITIONS MODIFYING THE CHARACTERS OF BACTERIA 1

. Spontaneous variations. Pleomorphism. Unexplained variations. 2. Geographical distribution. 3. Prolonged cultivation — extends survey — permits natural selection — influence of saprophytism. 4. Conditions of cultivation, (a) lowered vitality, (6) crowding of colonies, (c) temperature, {d) at- atmospheric pressure, (e) oxygen, (/) sunlight. 5. Ultra violet rays. 6. Electrolysis. 7. Age of culture — pleomorphism — other variations. 8. Culture medium— (a) age of medium, (6) reaction of medium, (c) nature of the medium — natural secretions— pathological exudations — ^water, {d) chemical sub-stances—carbolic acid, antiseptics, boric acid, potassium bichromate, sodium benzoate, glycerine, iodine trichloride, lactic acid. 9. Prolonged contact with particular foodstuff. 10. Artificial selection— method sometimes in- effective. 11. Symbiosis— lichens— nitrifying organisms— parasitism— anaerobes. Symbiosis may confer new powers— may have no effect. Methods of studying symbiosis— mixed growth, adjacent colonies, criss-cross planting, surface and deep growths, double celluloid sac, successive growth. 12. Parasitism, {a) transmission through alimentary canal, (6) passage, (c) celloidin sac in body cavity, {d) residence in living tissues, {e) during disease, (/) in "carriers." (13 — 27)



the book details :
  • Author: Samuel Gurney-Dixon
  • Publication date: 1919
  • Company: Cambridge, University Press

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