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STATE BOARD OJ^ AGRICULTURE 



develop into another cell; that is, a cell may produce a spore, but it dies in 

 the act; yet it has its life continued through the spore which will in turn 

 give rise to a cell. Sporulation does not mean multiplication but simply 

 a transmission of life. When the spore germinates, it throws 

 Eadoepores. oft' the sheath enshroudiug it and the young cell comes forth. 

 This mode of formation, when the spore is within the cell, is 

 called endospore formation. In this class the spores appear as bright 

 oval bodies, highly refrwctive, much more so than the protoplasm of the 

 cell, and markedly uniform. On the other hand, there are 

 Arthrosporee. those cells whicli become more refringent as a whole, seem to 

 resist staining reagents more than their associate bacteria, and 

 in short to assume the qualities of a spore. Such spores if 

 they do actually exist are called arthrospores. There are many bacteria 

 in which no spore formation has been observed; for this reason this indef- 

 inite class of arthrospores has crept in; still it bears with it considerable 

 valuable evidence. Certain spore bearing bacteria when grown 

 Asporosenic. under Unfavorable conditions will cease to produce spores. 

 Spore wall. Such bacteria are called asporogenic bacteria. The spore wall 

 which breaks away when the young microbe starts on its career, 

 is of the greatest importance in the bacteriological economy. 

 Resistance. It is perhaps One of the most resistant and impenetrable of sub- 

 stances making up plant life. Were it not for the spores, bac- 

 teria would be easily eradicated. They are exceedingly resistant to heat, 

 sunlight, dessication, stains and chemicals. Spores are known which will 

 resist twelve hours of steaming, will live for months in the direct rays of 

 the sun, will endure for years in dust, will not react to ordinary staining 

 methods, and will be unharmed after hours in a strong germicidal solution. 

 This feature of the morphology of bacteria plays a decided practical role 

 in bacteriology. The inability to sterilize milk is largely due to this char- 

 acteristic of some bacteria; the continuous existence of anthrax in some 

 localities is also based upon this fact. Spores are the most formidable 

 obstacles a bacteriologist has to contend with. 



GEOUPING OF BACTERIA. 



Besides the classification of bacteria founded upon forms and spores, 

 there is another not used so much to systematize bacteria, but to a con- 

 siderable extent as a characteristic in the identification of species. Some 

 bacilli always remain ununited with others of their kind; there are those 



which unite in pairs, 

 Threads. the eudsare coutiguous 



to each other, and still 

 those which form long threads or 

 rows, united end to end. Again 

 bacilli may have characteristic 

 groupings; the bacillus of tuber- 

 culosis is generally arranged in 

 clusters of three, four, or more 

 bacilli, and the grouping of these 



bacilli is not peculiar to any other 



variety. With the micrococci, the CX-M. 



groupings are more noticeable Fig. 7. Threads of baciiu. 



and pronounced. As with bacilli, micrococci may be arranged alone or in 

 pairs and other groups. They are not espeoiilly designated when existing 



