CONCLUSION 291 



their fruits are concerned) on lines of their own. They 

 are best regarded as forming by themselves a short 

 but distinct line of descent, which may have arisen 

 very far back, among organisms not yet characterised 

 as either animals or plants. In the plasniodial stage 

 the Myxomycetes would most naturally be regarded as 

 animals, especially when we consider their mode of 

 feeding. In the formation of their fruits and spores, 

 however, they rather suggest plants of the nature of 

 Fungi, but probably this is only a case of parallel 

 development, not indicating a real blood-relationship to 

 any undoubted members of the vegetable kingdom. 



The Bacteria are still more difficult to place, for 

 though in some ways we know so much about them, we 

 still do not know what they are. Possibly several 

 heterogeneous groups are included among them. Such 

 forms as Cladothrix show some affinities with" the Cyauo- 

 phycese, of which we took Nostoc as type, and, if it were 

 not for their ciliated swarm-cells, might be described as 

 Cyanophycese without pigment. The more typical Bac- 

 teria, however (such as Bacillus sultilis and its allies), 

 which are characterised by the production of endospores, 

 are still more unlike any other plants, and might be 

 placed in a neutral group lying at the base of both the 

 animal and vegetable kingdoms. Bacteria, however, offer 

 so few points for morphological comparison with other 

 groups, that nothing definite can be said at present as to 

 their relations. 



Nostoc, representing the Cyanophycese, is another ex- 

 tremely simple type, so far at least as our present 

 knowledge enables us to judge. It is probable, however, 

 that further research may show the cell-structure to be 

 more like that of the higher plants than it appears at 

 present. It is doubtful whether the Cyanophyceoe should 



