PROGRESSIVE STAGES IN COMPLEXITY OF STRUCTURE. 589 



in the pools where these species grow hundreds and thousands of separate nets are 

 to be found living together within a limited area. But the number of instances 

 of swarm-forming cell-complexes is, however, utterly insignificant in comparison 

 with the enormous number of those forms in which the tissues arising by re- 

 juvenescence remain connected. We call these permanently-connected cell-tissues 

 systems; and distinguish between systems of cell-rows, cell -nets, cell-plates, and 

 cell-masses. The arrangement of the individual parts, and the fitting together 

 of the systems is quite irregular, but is defined for each plant-species in the 

 established manner, inherited from generation to generation. The simple cell- 

 tissues which build up an extensive system can be distinguished as separate parts, 

 and may be compared to the members of a body, and even called members of that 

 system. There are, of course, systems which consist of very many simple cell- 

 tissues, and therefore have a much-membered appearance; and others which exhibit 

 only a slight organization, i.e. are built up of only a few simple tissues. Setting 

 aside the question of greater or smaller, the kind and manner of connection must 

 be taken into consideration in a general review of the forms of plants, and these 

 systems can be comprehended under two divisions. 



The first division comprises those whose members {i.e. cell-complexes) are all 

 of similar shape, so that the whole plant-body consists only either of cell-filaments, 

 or of cell-nets, or of cell-plates, or, finally, of cell-masses. These uniform systems 

 are found more especially in plants growing under water, which reproduce them- 

 selves by spores, as well as in fungi, and the commonest forms to be noticed are as 

 follows: — first, the clusters of tortuously twisted and intertwined rows of cells, like 

 strings of pearls, such as occur in the Nostocacese, the bundles of elongated, 

 straight filamentous rows of the Oscillatoriese, the flock-like Scytonema and 

 other aquatic plants, and the dark cushions of whip-like rows grouped in bundles, 

 as shown in the genera Euactis and Dasyactis. Among the series of complex 

 systems a particular interest is claimed by those which are produced from the 

 frequently-mentioned hyph83. When the branched hyphse, often knitted into 

 meshes, and united into net-works, are crowded together in great numbers, plexuses 

 and strands arise which have exactly the appearance of a cell-mass, but which 

 may be distinguished therefrom by the fact that neighbouring cells, whose sides 

 adjoin one another, are not produced by the intercalation of partition-walls. The 

 fungal hyphae have a common development and manner of growth; hundreds of 

 hyphal threads which are joined together into a strand or plexus continue to grow 

 at the apices with equal rapidity and in the same direction; they carry out in com- 

 mon the same curves and twistings, often divide into single threads, then reunite, 

 and thus form the most peculiar shapes. The so-called Hercules-club (Coryne 

 pistillaris), the strange forms of Glavaria, resembling pieces of coral, the Cap-fungi, 

 divided into cap and stalk, the Helvellas and Morels, the very peculiar pufi"-balls 

 and earth-stars, and many other forms are built up of hyphal strands and plexuses, 

 which, as already stated, are nothing else but conglomerated cell-nets. Systems of 

 cell-plates are more rarely to be met with. This construction is found most 



