ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 639 



part of the Myxomycetes, and that, as just stated, being one only of 

 degree and not of kind, consists in the fact that the final act, that of 

 encystment and the resolution of the body into spores, is in this group 

 accomplished by a mass of coalescing or conjugating units, which 

 consequently produce a relatively colossal spore-receptacle or sporan- 

 gium — the so-called fungus — while in the case of the typical 

 Flagellata it is an isolated monad or two, or a few conjugated units 

 only, that build up the relatively minute but otherwise morphologi- 

 cally and physiologically identical reproductive structure. 



" In every structural detail, and in every successive stage of their 

 life-history, the Myxomycetes or Mycetozoa, from their first exit from 

 the spore until their final resolution into similar reproductive elements, 

 may be consistently correlated with the typical Protozoa, and with 

 them alone. While in their compound aggregation, their production 

 of a horny rete or capillitium, and frequent excretion of spicular 

 elements, a departure is made in the direction of the Sponges, the 

 simple flagellate condition of the spore-derived units, and the capacity 

 possessed by them to ingest food-substances at all parts of theii 

 periphery, demonstrate their nearest affinity with the simple Flagel- 

 lata Pantostomata, and of which they may be accepted as representing 

 the most complex factors." 



The views of the author are, he considers, strongly supported by 

 Mr. D. D. Cunningham's description * of Protomyxomyces coprinarius. 

 This is an organism (developed in the intestinal canal of man, cows, 

 and other animals) which, while presenting an infinity of polymorphic 

 expressions, is reducible to the three component terms common to the 

 two groups of the Myxomycetes and ordinary monads, and which 

 indeed, as recognized by Mr. Cunningham, occupies a position pre- 

 cisely midway between these two series. " With the typical Myxo- 

 mycetes, Protomyxomyces agrees in so far as that the usually 

 relatively large sporangium represents the final disintegration into 

 spores of a multitude of closely associated amoeboid elements, sur- 

 rounded by a common membranous envelope studded with organic 

 granules, these amoeboid elements having again commenced existence 

 as simple flagellate monads. Dr. Cunningham's so-called ' zoospores.' 

 From the typical Myxomycetes, on the other hand, Protomyxomyces 

 differs in that the amoeboid beings thus building up the compound 

 sporangium do not coalesce intimately with one another so as to form 

 a common plasmodium, but while closely approximated, remain indi- 

 vidually distract, each amoeboid unit separating into an independent 

 spore-mass, after the manner of the typical Flagellata." 



Myxomycetes with Aggregated Plasmodiuin.t — As soon as the 

 processes of growth and bipartition of the myxamoebse of the Myxo- 

 mycetes are completed, from the exhaustion of the nutritive material, 

 the course of development continues in two somewhat different ways. 

 In the ordinary case, the myxamoebse fuse into an articulated Plasmo- 

 dium, endowed with both external and internal movements, and sub- 



* Quart. Journ. Micr. Sci., xxi. (1881) p. 287. 



t Bull. Soc. Bot. France, xxvii. (1880) pp. 317-22. 



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