4 DAIRY BACTERIOLOGY 



formed in a cell. As a rule, two, three or four spores are found 

 together (Fig. 7), and they generally grow by budding like the 

 ordinary yeast cells. 



When moulds form endospores (e.g., the various Mucors) this 

 takes place in specially shaped cells known as sporangia, which 

 may contain several hundred spores (Figs. 8 A and SB). As a rule, 

 however, the moulds form exogenous spores ; these are known as 

 Conidia when formed as constrictions on specialised spore bearing 

 members (Conidiophores) (see Figs. 3 and 9), and as Oidia when 

 formed on the ordinary branches of the mycelium (Fig. 10). 

 Considered as spores, the oidia are less characteristic than the 

 conidia ; the Chlamydospores, however, are exceptional, being 

 unusually thick walled oidia, which may be formed anywhere in 

 the mycelium (Fig. 11). In a chain of conidia, the outer members 

 are generally the oldest, and the inner ones the youngest. 



STRUCTURE AND CHEMICAL COMPOSITION OF CELLS 



The main constituent of the cell is a viscous jelly-like trans- 

 parent solution of proteins, known as protoplasm, which is the 

 living substance of the cell. It is an extremely complex mixture of 

 unstable compounds, which are largely built up of combinations 



FIG. 5. Clostridia. (After Praz- FIG. 6. Plectridia (After 



mowski.) Spore Formation 

 in the Common Butyric Acid 

 Bacteria. 



Migula.) Spore Forma- 

 tion in the Tetanus 

 Bacterium. 



All x 1,000. 



FIG. 7. Spore 

 Formation in 

 Wine Yeast. 

 (After Hans en.) 



of a considerable number of different amino acids. The feeble 

 acid and basic properties of these acids are also characteristic of 

 the proteins, a circumstance which enables the latter to combine 

 loosely with a vast number of other substances, thus fulfilling a 

 condition necessary for the vital processes. Oil drops and other 

 reserve foodstuffs are often found in the protoplasm, and as a rule 



