98 MORPHOLOGY AND CTJLTTTRE 01" MICROORGANISMS 



evidence, it can not be disregarded in the intimate study of bacterial 

 cells. Below is given in full the summary by the authors. 



Summary by Authors. — A comparative study of 42 strains of 

 bacteria has shown that the life cycles of these organisms are not 

 less complicated than those of other micro-organisms. As represen- 

 tatives of practically all groups of bacteria have been tested and all, 

 without exception, behaved essentially in the same manner, in all 

 probability analogous results may be expected with all species of 

 bacteria. 



"All bacteria studied live alternately in an organized and in an amor- 

 phous stage. The latter has been called the "symplastic" stage, be- 

 cause at this time the living matter previously inclosed in the separate 

 cells undergoes a thorough mixing either by a complete disintegration 

 of cell wall, as well as cell content, or by a "melting together" of the 

 content of many cells which leave their empty cell walls behind them. 

 In the first case a readily stainable, in the latter case an unstainable 

 'symplasm' is produced. 



"According to the different formation and quality of the symplasm 

 the development of new individual cells from this stage follows various 

 lines. In all cases at first "regenerative units" become visible. These 

 increase in size, turning into "regenerative bodies," which later, either 

 by germinating or by stretching, become cells of normal shape. In some 

 cases the regenerative bodies also return temporarily into the sym- 

 plastic stage. 



"Besides the formation of the symplasm, another mode of interac- 

 tion between the plasipatic substances in bacterial cells has been ob- 

 served, consisting of the direct union of two or more individual cells. 

 This "conjunction" seems to be of no less general occurrence than the 

 process first mentioned. The physiological significance remains to 

 be studied. 



' ' AU bacteria multiply not only by fission but also by the formation of 

 'gonidia;' these usually become first regenerative bodies, or occasion- 

 ally exospores. Sometimes the gonidia grow directly to full-sized 

 cells. They, too, can enter the symplastic stage. The gonidia are 

 either liberated by partial or complete dissolution of the cell waU or 

 they develop while still united with their mother cell. In the latter 

 case the cell wall either remains intact or it is pierced by the growing 

 gonidia, which become either buds or branches. 



