26 A Monograph of the Myxogastres. 



protuberances into which the whole of the protoplasm passes, 

 leaving behind the remainder of its pellicle attached to the 

 substratum, and known as the hypotliallus. When these 

 protuberances, which may be sessile or stipitate, are symmetrical 

 and individually distinct, they are called sporangia; when 

 sporangia are irregular in form, usually veinlike and creeping, 

 the term plasmodiocarp is used ; finally, when the sporangia are 

 densely aggregated, so that their individuality disappears to a 

 greater or less extent, an aethlium is produced. The three 

 conditions are connected by intermediate links. Aethalia are 

 most frequently sessile on a broad base, as in Tiibulina cylindrica 

 and Enteridivm olivaccum, but stipitate aethalia are not un- 

 common, especially in the Trichiaceae, where the transition from 

 typical sporangia to aethalioid forms in many species is very 

 instructive. 



As previously stated, the late Professor De Bary was the 

 first to show, by his admirable researches on the morphology 

 and physiology of the Myxogastres, that the systematic arrange- 

 ment then in vogue was no longer tenable, owing to the fact 

 that it was founded on analogies rather than affinities; and 

 although at the present day it must be admitted that, within 

 the group, affinities are far from being settled, yet, the appear- 

 ance of Dr. Rostafinski's Monograph based on De Bary's re- 

 searches, gave a fresh impetus to the study, and showed in a 

 masterly manner, that well-marked morphological features, far 

 beyond the ken of pocket-lens revelation, could be utilized in 

 connection with the systematic disposition of the members of 

 the group. Among the essentials still lacking for an approxi- 

 mately correct classification are more especially amount of 

 variability, as also its direction in the various sections ; the 

 relative value of such structures as the columella, capillitium, 

 sporangial, aethalioid and plasmodiocarp forms; the presence or 

 absence of lime, as also its amorphous and crystalline condition 

 as presented in different sections ; and finally, what is undoubt- 

 edly of primary importance, a complete knowledge of the life- 

 history of at least the representative species of each section ; and 

 although complete life-histories might not in all cases be 



