SYNOPSIS 



INTRODUCTION 



CHAPTER I 



THE SCOPE OP THE ENQUIRY 



Definition op Terms. Transmutation not evolution — evolution in bac- 

 teria — its stages. Natural variation — "Spontaneous" and "impressed." Varia- 

 tion easily studied in bacteria — unicellular organisms — method of generation 

 — rapidity of generation — environment easily modified. Natural selection. 

 Artificial selection. "Transmutation of Species" apparently contradictory — 

 meaning of "species" — based on characters. Arbitrai7 nature of 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. 



A CONSIDERATION OF THE POSSIBILITIES. 1. Simple Variation. 2. Varia- 

 tions in dififerent directions associated. 3. Development of intermediate 

 forms. 4. Slight changes in closely allied organisms. 5. Complete change in 

 characters. (Pages 3 — 12) 



CHAPTER II 



CONDITIONS MODIFYING THE CHARACTERS OP BACTERIA 



1. Spontaneous variations. Pleomorphism. Unexplained variations. 

 2. Geogi-aphical distribution. 3. Prolonged cultivation — extends survey — 

 permits natural selection — influence of saprophytism. 4. Conditions of culti- 

 vation, (a) lowered vitality, (6) crowding of colonies, (c) temperature, {d) at- 

 mospheric pressure, (e) oxygen, (/) sunlight. 5. Ultra violet rays. 6. Elec- 

 trolysis. 7. Age of culture — pleomorphism — other variations. 8. Culture 

 medium— (a) age of medium, (6) reaction of medium, (c) nature of 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— anaer- 

 obes. Symbiosis may confer new powers— may have no eflfect. Methods of 

 studying symbiosis— mixed growth, adjacent colonies, criss-cross planting, 

 surface and deep growths, double celluloid sac, successive growth. 12. Para- 

 sitism, {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) 



