374 THE BEGINNINGS OF UFE. 



molecules of such simple organisms may rearrange 

 themselves, and, under the influence of disturbing con- 

 ditions, may fall into new, simple and compound modes 

 of aggregation. Thus new centres of attraction may 

 arise, new current modes of activity may be initiated, 

 and new organic forms may result. So that the con- 

 stituent elements of the previous organism may be still 

 present, living and mobile, although differently com- 

 bined, and variously reacting upon the ethereal pulses 

 of heat and light to which they are subjected. In 

 some such manner must we explain the occurrence of 

 the various metamorphoses of living matter of which 

 we are about to speak. 



Nearly twenty years ago. Professor Pringsheim ^ 

 called attention to the production of what he believed 

 to be a peculiar kind of propagative spore, in the cells 

 of young filaments of Sp'irogyra jugalts^ and also in 

 certain conjugated cells of the same Alga before, and 

 indeed instead of, the production of the ordinary rest- 

 ing spores. He says he frequently found, in conju- 

 gated filaments, 'that the contents of one or more 

 pairs of conjugated cells were not transformed into 

 the well-known large spore.' They, however, ' became 

 transformed into a number of little cells of regular, 

 definite, and unchangeable form,' whose constant oc- 

 currence led Dr. Pringsheim to conjecture that they 

 were ^ more than mere pseudo-forms of decaying cell- 



1 ' Ann. and Mag. of Nat. Hist.' 1S53, vol, xi. 



