THE DYNAMIC ELEMENT IN LIFE. 119 



lining chromatophore made of nucleated protoplasm with 

 immersed chlorophyll-grains. This, when the cell is adult, 

 divides into multitudinous zoospores, which presently join 

 their ends in such ways as to form a network with meshes 

 mostly hexagonal, minute in size, but like in arrangement to 

 the network of which the parent cell formed a part. Event- 

 ually escaping from the mother-cell, this network grows and 

 presently becomes as large as the parent network. Under 

 what play of forces do these zoospores arrange themselves 

 into this strange structure? 



Kindred insoluble problems are presented by animal or- 

 ganisms of all grades. Of microscopic types instance the 

 Coccospheres and Rhabdospheres found in the upper strata of 

 sea-water. Each is a fragment of protoplasm less than one- 

 thousandth of an inch in diameter, shielded by the elaborate 

 protective structures it has formed. The elliptic coccoliths 

 of the first, severally having a definite pattern, unite to form 

 by overlapping an imbricated covering; and of the other the 

 covering consists of numerous trumpet-mouthed processes 

 radiating on all sides. To the question — How does this 

 particle of granular protoplasm, without organs or definite 

 structure, make for itself this complicated calcareous ar- 

 mour? there is no conceivable answer. 



Like these Protozoa, the lowest Metazoa do things which 

 are quite incomprehensible. Here is a sponge formed of 

 classes of monads having among them no internuneial appli- 

 ances by which in higher types cooperation is carried on — 

 flagellate cells that produce the permeating currents of 

 water, flattened cells forming protective membranes, and 

 am(eboid cells lying free in the gelatinous mesoderm. These, 

 without apparent concert, build up not only the horny net- 

 work constituting the chief mass of their habitation, but also 

 embodied spicules, having remarkable symmetrical forms. 

 By what combined influences the needful processes are 

 effected, it is impossible to imagine. 



If we turn to higher types of Metazoa in which, by the 

 9 



