Dr. A. de Bary on the Mycetozoa. 241 



Indeed the difference between the Mycetozoa and those beings 

 nearest akin to them is very much wider than that between the 

 cells of any other divisions of the vegetable kingdom; on the other 

 hand, their structure, vital phaenomena, and movements bear 

 the closest resemblance to many animal organisms, and so much 

 so to the Rhizopoda (figs. 9, 13) that their sarcode-nbres are all 

 but indistinguishable from them except by their much greater 

 magnitude. 



Admitting therefore theMyxomycetes to be of an animal nature, 

 and referable to the animal kingdom under the name of Myce- 

 tozoa, it yet remains questionable to what division of that king- 

 dom they should be assigned. Naturalists have of late treated 

 the Amoebae as one division of the Rhizopoda, but this relation- 

 ship must, in the case of the Amoebae of the Mycetozoa, be 

 looked upon as very doubtful, inasmuch as there is little in their 

 developmental history in common with that of the testaceous 

 Rhizopods. At present it would seem best to regard the Myce- 

 tozoa as a special order, agreeing on the one hand with the 

 Rhizopods in the structure of their bodies and their variety of 

 movements, and on the other, with the Gregarinae by unmis- 

 takeable affinities in the whole cycle of development. 



The next question that arises is : Are all the Amoebae merely 

 developmental phases of the Mycetozoa ? or are only some such, 

 and others similar phases of other animals ? or have some an 

 independent existence as species ? Direct observations are want- 

 ing to determine these points ; but this much is certain that 

 cells possessing the peculiar movements of Amoebae occur as 

 embryonic stages of higher or of lower animals, of unicellular 

 and few-celled organisms. The Arncebiform cells which issue 

 from Psorospermia, and are transformed into Gregarina, may be 

 cited in illustration, as may be also the Amoeba- moving organisms 

 seen by Lieberkiihn and Schenk to issue from the saccular cells 

 found parasitic on the larvae of insects and Crustacea. The 

 Amoebae of the Mycetozoa afford a third example. 



Considering these facts to be indicative of the part played by 

 Amoebae in the cycle of development of other animal forms, 

 in connexion with that of the failure of observers to distin- 

 guish any definite plan of development belonging to them as 

 distinct animals, it appears highly probable that these beings 

 generally have no claim to be regarded as independent existences 

 or determinate species, but simply as developmental phases of 

 other beings. 



This being granted, there is still no sure proof that the aquatic 

 Amoebae belong to the developmental cycle of the Mycetozoa; 

 nor, on the contrary, are there sufficient arguments against the 

 hypothesis. There is no doubt that the aquatic Amoebae agree 



