CRITICAL EVENTS IN THE LIFE HISTORY OF CERATIOMYXA

Abstract

Over two hundred years ago Micheli (I729) described and illustrated Ceratiomyxa under the name Puccinia ravtosa. The next important record is that of Albertini and Schweinitz (IS05) in which they describe two species, Ceratium hyddnoid'es and Ceratium porioides. Numerous descriptions of forms thought to be species have been written. Lister (I925) includes all of these in one species as Ceratiomyxra frutticulosca Macbr. In North American Slime Moulds, Macbride (i922) gives specific rank to the form porioides. Both Lister and Macbride include a list of synonyms with their descriptions of Ceratiomyxa. Three life history studies of Ceratiomyxa have been made. These are by Famintzin and Woronin in I873, Olive in I907, and Jahn in I908. Famintzin and Woronin made no cytological observations but gave an accurate account of the morphology of the pillars. Perhaps their greatest contribution is in the excellent plates which they prepared. These are the best illustrations of Ceratio myxa yet published. Olive (1907a) obsenred that a condition resembling synapsis occurred in the young spores. From this he concluded that the two nuclear divisions in the spore were apparently reduction divisions. He further concluded that since there is a reduction in the spore, there must be a fusion of nuclei somewhere in the previous life history. Later, in a brief note, Olive (09o7b) claimed that he had found nuclear fusion occurring about the time of cleavage in the pillars. Lacking cytological proof of these claims, Olive's work has been superseded by the more detailed observations of Jahn (I908). Jahn reported fusion as occurring about the time of emergence of the plasmodiunm from the wood and the first reduction division as occurring just before cleavage. Because of the difference between the conclusions of Olive and those of Jahn, this study of Caratiomyxa was undertaken.