1892.] NEW-YORK MICROSCOPICAL SOCIETY. 17 



chrome. It is this mysterious, active matter which, with a chem- 

 istry peculiar to itself, gathers up the soluble silicates from the 

 water in which it lives, and builds them into its enclosing tissue 

 or film to form its beautiful glass-like shell, and it is this same: 

 restless and expanding endochrome which, in multiplying itself by 

 binary subdivision, pushes apart the valves of its containing case, 

 and, as fast as it thus gains room, constructs in the enlarging 

 chamber new siliceous walls encasing the nascent pair of diatoms 

 into which the growing frustule is divided. Thus it comes about, 

 by imperceptibly fine transitions, that the crystal jewel-case and 

 its delicate, living contents are, at one and the same time, trans- 

 formed, by the natural magic in which the microscopical world 

 abounds, into duplicate descendants hardly distinguishable front 

 each other and closely resembling in every particular the parent 

 form whose individuality is lost in the new units which have takea 

 its place. This remarkable operation is going on every minute, 

 and in countless centres of vital activity throughout the whole 

 world, and of course it has been going on for numberless ages. 

 since the first diatom or its evolutionary progenitor made its ap- 

 pearance in the waters of the earth. There is exceedingly strong 

 probability too that this dividing and subdividing will continue 

 during all time to come; and so, whether we regard the matter 

 retrospectively or in anticipation, we perceive a practically endless 

 chain of diatom-life, through which threads an unbroken line of 

 protoplasmic succession. In the higher orders of living thinga 

 one generation passes entirely away and the following generatioa 

 sooner or later becomes the head of the family or race. But 

 amongst the lowest creatures, when one bit of animate jelly be- 

 comes two bits of animate jelly, the distinction of generations. 

 cannot be preserved and there is a nearly strict continuity and 

 identity throughout the genetic line from beginning to end. In. 

 other words, the stream of living matter flows on forever, its com- 

 ponent substance never disposed twice in exactly the same man- 

 ner, yet always essentially the same stream. Some portion of it 

 undergoes chemical transformation from time to time, and the; 

 waste is supplied by acquisitions of new material, as the water of 

 a river is evaporated and replenished, but the identity of the 

 stream is, in a sense, never lost. On this conception has beea 

 erected an ingenious theory of immortality, in which the ideaL 



