PROPAGATION BY SPOT 161 



this zoogkea mass the division of the individual cells 

 can continue, leading to a denser accumulation in the 

 zooglaea. The fission is as a rule completed very 

 rapidly ; at 35 C. complete division was observed in the 

 bacilli at the end of 20 minutes ; external and individual 

 influences may cause variations as regards the time, but 

 it is evident that the the fission fungi can multiply to 

 an enormous extent in one or a few days. If we start 

 with a single bacterium and assume that each indi- 

 vidual requires an hour to grow and divide, we find tha 

 in the course of a day about 16 million organisms 

 have been formed, while by the end of the following 

 day the number has reached several billions. 



2. Propagation by Spores. 



Besides multiplication by fission we find a true fructi- 

 fication, a spore formation, in many fission fungi under 

 special circumstances, chiefly, but not exclusively, when 

 the nutriment is becoming exhausted. Fructification 

 by endospores and by arthrospores may be observed ; of 

 these the first is the most important and most definitely 

 ascertained mode of spore formation. This occurs in 

 various bacilli, and perhaps in some spirilla, but the 

 process varies in different species. In many cases the 

 bacilli grow to ^^ 



long threads be- ^r ^ \ 



fore the forma- f * . ft %t & 



tionof spores;) J'/Hj /, I JV 

 under favourable "I I fl I* 



conditions they ywr M SOOT* <<n~- s. ,r4~., t^u ^ 



J -* *& * <W*- ?JA/TV I CrKTHBUCm Tm W1QW jEDKMf Off 



may attain even wan x 7*t. 



in a 4 hours 20 times the length of the original 

 bacillus. The threads may be nrach twisted, united in 

 bundles or interworen to form a thick network, and they 

 have pale homogeneous contents. After some hours the 

 segmentation of these pseudo-threads begins and becomes 

 more distinct; at the same time the contents become 

 turbid and less in amount, and highly refracting granules 

 appear in the threads at regular inteirals. Afterabooi 



II 



