x SYNOPSIS 



CHAPTER III 



A CONSIDERATION OF THE EVIDENCE 



1. Contamination. Growth from single bacterium. 2. Mixed infection 

 error due to (a) unequal growth of two strains, (6) incomplete recognition. 

 Proof of continuity necessary. 3. Secondary invasion. Bacteria in healthy 

 organs. Post mortem invasion. 4. Repetition of experiment. 5. Constancy 

 of new feature meaning of "permanent." 6. Perseverance necessary. 

 7. Faultless technique (e.g. agglutination) and accurate observation (e.g. 

 staining) required. 8. Methods may require to be improved, (a) irregular 

 results due to media e.g. sugars, may be impure, contaminated by glass, 

 affected by sterilisation, deteriorate age of medium composition re- 

 action, (b) age of culture, (c) time allowance. 9. Clinical observation im- 

 portant, e.g. Widal's test in jaundice effect of drugs pre-existing disease. 



(2836) 



CHAPTER IV 



VARIATIONS IN MORPHOLOGY 



A. ZOOGLEIC FORMS not fortuitous B. radicicolaBeggiatoa versatilis. 

 Zoogleae not in strict sense individuals analogy of regiment of soldiers and 

 crowd of pitmen typical formations assumed not separate individuals like 

 a tree formations not invariable may simulate each other this does not 

 imply transmutation. I. Zoogleic forms occurring spontaneously stages 

 in life history or variations. B. rubescens other examples. II. Zoogleic 

 forms artificially produced, 1. Due to chemical substances salt, sewage, 

 urea, saliva, bile, acid, caustic soda, /3 naphthol, alcohol, potassium bi- 

 chromate, boric acid, nitrates, antiseptics, tartaric acid. 2. Temperature. 

 3. Absence of oxygen. 4. Ultra violet rays. 5. Growth in animal body. 



B. VARIATIONS IN INDIVIDUAL ORGANISMS. I. Pleomorphism B. ru- 

 bescens other examples. 1 1. Variations due to environment. 1 . Geographical 

 distribution. 2. Prolonged cultivation. 3. Crowding of colonies. 4. Changes 

 in medium reaction. 5. Chemical substances urea, urine, carbolic acid, 

 creosote, nitrogenous substances. 6. Ultra violet rays. 7. Electrolysis. 

 8. Symbiosis. 9. Growth in living tissues. 



C. VARIATIONS IN COLONIES. 1. Colonies of the same organism vary. 

 2. Different organisms produce similar colonies. 3. Addition of various 

 substances to medium affects colonies. 4. Influence of heat. 5. Effect of 

 "passage." 



Variation in other morphological characters. (37 49) 



