

INTRODUCTION. 





FOR half a century the Myxomycetes have been classified on the 

 basis of external characters alone, or such only as could be dis- 

 cerned by the aid of a pocket lens. In one or two instances an 

 additional genus has been constituted in which some prominence 

 was given to characters determined by the aid of the microscope, 

 as for instance in the genus Badliamia proposed by Berkeley in 

 1851, but the general feature of the classification was one of 

 external characteristics. The advance of Microscopy left behind 

 such an incomplete system for many years, and at length Professor 

 de Bary turned his attention to the subject but made no definite 

 propositions for a rectification of the classification, until in 1873 

 his pupil at Strasburg, Dr. Joseph Rostafinski, published in an 

 inaugural address the outlines of a system of classification, based 

 on new principles. In 1875, the more elaborate, and detailed 

 " Monografia Sluzowce " expanded and illustrated his views in a 

 complete and almost exhaustive manner. This work being, un- 

 fortunately, printed in the Polish language, and most difficult to 

 obtain through the ordinary channels of trade, it appeared advis- 

 able to present to English readers as much of it as referred to 

 British species in a more familiar language, and hence the present 

 work. 



At first Rostafinski recognized in the " Mycetozoa," as he 

 termed them, two primary divisions, in one of which the spores 

 were developed externally, on the surface of certain definite 

 spore-bearers, and in the other they were developed internally, 

 covered at first by a protective membrane or sporangium. In 



