2 



MYCETOZOA AND RELATED ORGANISMS 



UNDER this title are brought together several groups of organisms 

 which are probably interrelated but whose relationship to the true 

 fungi is very doubtful. As mentioned in the preceding chapter the author 

 follows de Bary (1887) in considering them to be more nearly related to 

 members of the Animal Kingdom. They are discussed in this chapter 

 because, for several hundred years before their hfe histories were known, 

 botanists looked upon their mature fruiting bodies as fungi and gave 

 them names, many of which are still maintained. Because they are more 

 usually considered, even at this date, as fungi, they are given a place in 

 this text. 



These organisms all agree in the fact that they are naked during all 

 stages of development except the culminating spore stage. Mostly for a 

 portion or for the whole of this naked stage they are more or less amoeboid 

 and ingest particles of food, rejecting the portions remaining after diges- 

 tion is accomplished. At germination of the spore the escaping naked 

 protoplast may be a simple uninucleate amoeboid cell, or myxamoeba, 

 or it may be provided with one or two anterior flagella which eventually 

 are retracted, leaving the cell a myxamoeba. To a greater or less degree 

 both the planocytes and the myxamoebae are capable of multiplication 

 by fission. Usually after a while the myxamoebae, through the division 

 of the protoplast, become multinuclear plasmodia, or these may arise 

 by the fusion of separate myxamoebae as well as by growth and nuclear 

 division. In the better known groups there is usually a sexual stage, and 

 eventually, just before spore formation, a meiotic division of the nuclei 

 of the Plasmodium so that the encysted spores contain haploid nuclei. 



These organisms are usually classified by the zoologists as belonging 

 to Phylum Protozoa, Class Sarcodina (or Rhizopoda). This classification 

 is quite different from that mostly used by botanists. In the following 

 pages an attempt will be made to reconcile these two viewpoints, yet 

 maintaining so far as possible the nomenclature with which botanists, in 

 particular mycologists, are more or less familiar. Four orders will be 



22 



