X «V .J. THOJISON, M.B. 



Imcillifx (tnt/iftii-i.s, <■■** and that may b« taken as the year when 

 Bacteriology, as a special study, had its birth. Ita infancy was 

 both puny and capricious, and it was not until 1880, thai the 

 foundations of an absolutely sound constitution were laid ; 

 " the work done earlier than that was more likely to be 

 erroneous than correct." But the first and the greatest of 

 the bacteriologists was the Frenchman, Louis Pasteur ; to him 

 undoubtedly belongs the honour of having been the mosb 

 successful experinu nter, the most careful worker, and the most 

 original thinker in the new field of science. He led, others 

 followed ! 



Many attempts have been n.ade to classify Bacteria — a term 

 certainly erroneous, but now universally employed when referring^ 

 to the Schizomycetes, or Fission Fungi — a group of minuta 

 unicellular vegetable organisms which reproduce themselves by 

 self-division or cleavage. 



The simplest classification, '•'• based on morphological char- 

 acteristics, that is, shape and form, is : — 



I. Cocci. — '^' Are small oval or spheroidal cells, always 

 retaining their shape, no matter in what natural or artificial 

 media they may grow. 



1. Diplococci : **-^' When the cells are in pairs, as in the 



pneumococci and others. 



2. Streptococci : '"■'^' When the cells are in chains, short or 



long, usually enca^jsuled. 

 y. Tetracocci : ''^' When the cells are grouped in fours, often 



encapsuled. 

 4. Sarciuse : *^'" When the cells appear in packets of eight 



or more. 

 0. Staphylococci: When the cells are in irregular clump* 



of no particular shape or symmetry. 

 6. Zoogloea : When clusters of staphyloccoi are held together 



by a tough mucous membrane 



11. Bacilli. — Are rod-like structures, in which one diameter 

 is greater than the other. They may be long and thin, or plump 

 and almost round ; they may have square, '^^"^-' pointed, 

 rounded, "^S' or clubbed *^*' ends, and they may arrange themselves, 

 in pairs, clumps, chains, or filaments. When fusiform or spindle 

 haped they are sometimes called Clostridia. 



The numbers in the text I'efer to the lantern slides exhibited during the 

 address. A list of these slides is given in an appendix. 



