CONCLUSION 291 



a fairly high stage of development (so far at least as 

 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 plasmodial 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 pretty clear affinities with 

 Cyanophycese, of which we took Nostoc as type, and 

 may be described as Cyanophycese without pigment. 

 The more typical Bacteria, however (such as Bacillus 

 siibtilis and its allies), which are characterised by their 

 cilia and endospores, are 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, are so little known morphologically 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 possible, however, 

 that further research may show the cell-structure to be 

 more like that of the higher plants than it appears at 



