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INTRODUCTION 



I. General Morphology 



The Myxomycetes are fungus-like organisms characterized by an 

 assimilative phase consisting of a naked, multinucleate, mobile mass 

 of protoplasm, the Plasmodium, and a reproductive phase, consisting 

 in most instances of a membranous spore-case. The latter often con- 

 tains, in addition to the spores, a system of netted or free threads, form- 

 ing the capillitium, and frequently bears, within or without, calcareous 

 accretions of specific character. The spore, on germination, emits a 

 vesicle which gives rise to one or more swarm-spores, each with an an- 

 terior flagellum; or it may produce the swarm-spores directly. These 

 feed and multiply, eventually function as gametes and fuse in pairs 

 or sometimes larger groups. The zygote so produced is the first stage 

 of the Plasmodium. It grows, with multiplication of nuclei, and 

 also in some cases, perhaps usually, by combining with other Plas- 

 modia, and under appropriate conditions, produces the fructification. 



As here presented, the Myxomycetes are regarded as constituting 

 the first and simplest class of the Fungi, coordinate in rank with the 

 Phycomycetes, Ascomycetes and Basidiomycetes. Certain members 

 of the group have been noted by careful observers for nearly three 

 hundred years. Lister cites Pankow's figure and description, 1654, 

 of the species now known as Lycogala epidendrum. Ray, in 1690, called 

 the same species Fungus coccineus etc.; Ruppenius, in 1718, Lycoperdon 

 sanguineum etc.; Dillenius, a year later, Bovista miniata; Buxbaum, 

 in 1721, Lycoperdon epidendron. In 1729, Micheli erected the genus 

 Lycogala for it and at the same time added recognizable descriptions 

 and illustrations of several other genera and even species. But Micheli's 

 light was too strong for his generation. As Fries, writing a century 

 later, says "immortalis Micheli tarn claram lucem accendit, ut suc- 

 cessors proximi earn ne ferre quidem potuerint." Notwithstanding 

 Micheli's clear distinctions, he was entirely disregarded and the little 

 Lycogala was dubbed Lycoperdon and Mucor down to the end of the 

 century. It was not until 1794 that Persoon came around to the 

 standpoint of Micheli and wrote Lycogala miniatum. Fries himself, 

 reviewing the labors of his predecessors, grouped the slime molds as 

 a suborder of the Gasteromycetes, although clearly recognizing the 

 peculiar character of their assimilative phase, and gave expression to 



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