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AFFINITIES OF THE Mycetrozoa. By EpcGar W. OLIVE. 
The chief interest which invests this group of low organisms lies in the 
fact that the individuals possess a dual relationship; during one stage of 
their existence resembling certain members of the animal kingdom, while 
during another, they bear many resemblances to the plant kingdom, . 
through the fungi, with which they agree somewhat in the structure of 
their organs of reproduction and spores. 
The spores, on germinating, produce swarm-cells and plasmodia, in- 
stead of mycelium. The swarm-cells, or myxamcebee, resemble the naked 
amcebe of the animal kingdom, while the remarkable plasmodium, al- 
though there is no parallel among undoubted animals, seems to partake 
almost wholly of characters agreed by scientists to be clearly animal. 
The sporangium has a membranous wall sometimes resembling the 
cellulose walls of plants, and its cavity is filled with free spores and in 
many species a scaffolding support of threads called the capillitium. 
Probably the resemblance of this reproductive stage to the fungi is of very 
small amount, being confined to purely external resemblances. 
The Mycetozoa, as defined by DeBary, embraces two distinct groups, 
che Myxomycetes of Wallroth, and in addition the Acrasiew of Van Tieghem, 
evidently resembling each other very closely in the fact that their spores 
send forth swarm-cells which exhibit amceboid movements. The only 
important difference between the two is the formation of plasmodia by the 
coalescence of swarm-cells in the former and the formation of pseudoplas- 
modia by the aggregation of the swarm-cells in the Acrasiew. It was re- 
garded by DeBary as easy to conceive of the common origin of these two 
closely related groups or of the development of the one from the other. 
He says that probably the Myromycete plasmodium was evolved from the 
aggregation plasmodium, since the latter appears to be the less complex 
form and its fructification much simpler; possibly the development took 
place in the converse order. 
Botanists seem never to have questioned the homology of the pseudo- 
plasmodium of the Acrasiee with the plasmodium of the Myxromycetes. 
This plasmodium is strictly vegetative; during this period nourishment is 
imbibed. ‘The pseudoplasmodium is not vegetative; it is simply prelim- 
inary to the reproductive stage by the aggregating of individuals. It fol- 
lows, then, the strictly vegetative stage. If lack of analogy can thus be 
14—ScigEnceE. 
