LIVING SUBSTANCE 



73 



network be observed some hours after it is first seen, or upon the 

 next day, it is found that not only its place but its shape has been 

 completely changed ; and if a small piece be cut off from it, laid 

 upon a glass plate and kept in a moist place, it can be seen how 

 the whole mass begins to flow slowly and to send out delicate pro- 

 cesses in this and that direction, which branch in an arborescent 

 manner and flow together into a network. In short, it is seen 

 that the whole network is living. Myxomycetes consists of com- 



FIG. 14. Caulerpa, a leaf-shaped marine alga ; the single leaves are thin, protoplasmic lamella; 

 enclosed between two flat cellulose walls and containing numberless small nuclei ; natural 

 size. (After Reinke.) 



pletely naked protoplasm. Microscopic examination and staining 

 reveal in the fine strands of its plasmodia a large number of 

 nuclei, which are continually being dragged along by the slowly 

 flowing protoplasm and which roll over and under one another, 

 plainly showing that they possess no fixed position but change 

 their places constantly and irregularly in the unitary protoplasmic 

 mass. Here individual cell -territories are not marked off within the 

 protoplasmic body. According to the above criterion, therefore, 

 we would be obliged to regard the plasmodia as multinucleate 



