XXVIII. A STUDY OF SOME MINNESOTA 

 MYCETOZOA. 



Edmund P. Sheldon. 



In the course of an extended study of a number of specimens 

 of Mycetozoa collected by the members of the field staff of the 

 Geological and Natural History Survey of Minnesota, several 

 facts have been noted which tend to show the importance of 

 a systematic examination of these organisms. 



The delicate and beautiful characters of both the plasmodial 

 and sporangial stages of the slime- moulds have attracted the 

 attention of botanists and zoologists. Some writers have class- 

 ified them as plants, others as animals, and by still others they 

 have been placed outside both the animal and vegetable king- 

 doms. Just what position they should occupy in a natural 

 system of classification is hard to determine; but it is probable 

 that the more study is given to the morphology of this and 

 related groups, the less tendency either botanists or zoologists 

 will have to include them in either the animal or vegetable 

 kingdom. 



A knowledge of the life cycle of a slime-mould is necessary 

 to a good understanding of both the plasmodial and fruiting 

 stages. A spore, when surrounded by the requisite conditions 

 of temperature, moisture, etc., will germinate; the contents 

 will ooze out and take the form of a small, irregular-shaped, 

 often ciliated mass of protoplasm. The result of the germina- 

 tion of several such spores is a number of small bits of naked 

 protoplasm. These are the swarm-cells. Soon a number of them 

 fuse together forming the Plasmodium. These plasmodia, which 

 vary much in size and color in the different species, are merely 

 masses of protoplasm which increase in size by taking up all 

 sorts of bodies, both organic and inorganic. This is the vegeta- 

 tive or plasmodial stage of the slime-mould, a study of the devel- 

 opment of which is much needed, even in the more common 

 species. Rex has contributed somewhat to the knowledge of Tu- 



