6 A Monograph of the Myxogastres. 



plasrnodia possess the power of passing into a temporary 

 sclerotioid or resting stage ; the preliminaries for this condition 

 are the breaking up of the protoplasm into innumerable roundish 

 or polyhedric cells with an average diameter of from 25 40 /u.. 

 In some species, as Fuligo and Didymium serpula, the cells 

 become surrounded by a distinct, colourless membrane, which 

 shows the reaction of cellulose with iodine and sulphuric acid or 

 with Schulze's solution. 



In the Acrasieae, the spores on germination give origin to 

 ameboid swarm-cells, ciliated cells never being produced ; 

 after undergoing repeated bi partitions, the swarm-cells form 

 dense masses, but although crowded together, do not coalesce ; 

 this crowding together without loss of individuality constitutes 

 what De Bary terms, aggregation of swarm-cells. 



From the above account we learn that the coalescence of 

 naked, motile cells, or even the aggregation of naked motile 

 cells without loss of individuality, is, from De Bary's standpoint, 

 the proof that the Myxogastres are not plants. 



Naked or primordial cells are as a rule motile ; in fact a 

 considerable amount of motility is usually exhibited by proto- 

 plasm when imprisoned in a cell-wall ; hence we may presume 

 that motility, being so general, is not an important factor in 

 the character that proves Myxogastres to be animals; in fact 

 De Bary admits that the differences between the Mycetozoa 

 and the Fungi " would not be less decided if the Mycetozoa were 

 without their remarkable movements, for such movements are 

 observed in other vegetable cells which have not a firm 

 membrane." The Acrasieae show that the coalescence, with 

 loss of individuality of the component cells, may be omitted 

 from the character that separates the Myxogastres from 

 plants; hence we find that the only point not neutralized 

 by De Bary's own statements is that of naked cells; conse- 

 quently we may, by following De Bary's reasoning, formulate 

 the character that excludes the Myxogastres from the vege- 

 table kingdom as follows Cells naked during the entire vege- 

 tative, period. 



Notwithstanding the fact that the above definition covers 



