MYXOMYCETES. 207 



gelatinous matter, which appears to be formed by a partial 

 degradation of the walls of the cells. They are mostly 

 aquatic ; and the species which are terrestrial live in damp 

 and generally shaded places. 



I. CLASS MYXOMYCETES. THE 'SLIME MOULDS. 



272. In this class is ijfcluded a large group of remark- 

 able organisms, which differ in many respects from all other 

 vegetable structures. In many of their characters, as in 

 having no cell-wall during the period of their active growth, 

 in being destitute of a nucleus, in their mode of nutrition, 

 and in the motility of their naked protoplasm, they resemble 

 certain Monera among the Protozoa ; * while, on the other 

 hand, they have a close external resemblance to certain 

 higher fungi (puff-balls and their allies). 



273. It is difficult to give the Myxomycetes a satisfac- 

 tory place in a system of classification. They have no struc- 

 tural affinities with plants higher than they are, nor with 

 any lower ; they stand alone, and appear to belong to a dif- 

 ferent genetic line. So, although taken up here, they must 

 not be regarded as on that account the lowest or the first of 

 the Protophytes. 



274. All members of this class agree in being composed 

 during the vegetative portion of their existence of naked 

 masses of protoplasm (Fig. 140), which are yellow, brown, 

 purple, etc., but never green. These plasmodia, as they are 

 called, are, during the period of their active growth, endowed 



* There are fewer reasons nowthan formerly against regarding these 

 as near relatives of the Monera. We no longer imagine an absolute 

 line of separation between the lower portions of the great domain of 

 life, and hence may now admit relationships which formerly were in- 

 admissible. It is by no means an improbable hypothesis that in the 

 Myxomycetes we have the terrestrial phase and in the Monera the 

 aquatic phase of a common group of organisms. The Myxomycetes are 

 not Monera, but they are Moneran in their structure, and probably also 

 in their affinities. All the differences between the Myxomycetes and a 

 Moner like Protomyxa, for example, are probably referable tC the 

 terrestrial habit of the former as contrasted with the aquatic habit of 

 the latter. 



