ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 823 



tion is paid to the radiating pseudopodia with their axial filaments. 

 In lower forms, however, more attention is paid to the whole life- 

 cycle. In the Amoeba the encysted state is almost as familiar as the 

 active, in the Gregarine sometimes more so, while in such a remark- 

 able Moneron as the Protomyxa of Hackel it is hard to say whether 

 the encysted, the amoeboid, the flagellate or the plasmodial is the 

 most prominent stage. For here is no single permanent highly 

 differentiated form, but an eventful life-history in which one protean 

 mass of protoplasm passes through the cycle of at least four distinct 

 phases. 



Such discoveries as those of the life-history of Monads, of the 

 ciliate embryo of Acinetce, of the multiplication of Eadiolarians by 

 zoospores, or of the union of several Actinosphceria or Gregarines 

 into a Plasmodium, point in the same direction — in fact the whole 

 progress of recent research has largely lain in revealing the existence, 

 in even the most highly differentiated forms, of a life-cycle almost as 

 complete as that of Protomyxa. 



In other words, if we make a diagram ot Protomyxa, exhibiting the 

 encysted, the ciliated, the amoeboid, and the plasmodial stages, an 

 essentially similar life-history may be sketched out for all the higher 

 groups of Protozoa, with blanks it is true, but blanks which the pro- 

 gress of discovery is constantly diminishing, and seems likely indeed 

 wholly to fill. In short, a Heliozoon differs from Protomyxa (over 

 and above its possession of a nucleus) merely in the excessively high 

 differentiation and relative permanence of the amoeboid stage of its 

 life-cycle : the Monad or the Infusor has similarly developed its 

 ciliated stage, the Myxomycete its plasmodial. In the Protophyta 

 the resting or encysted stage certainly predominates, but they too 

 show phases of the same life-cycle, as the naked motile zoospores of 

 so many Fungi and Algoj (which as " a transition from plant to animal 

 life " so perplexed the elder botanists) and the amoeboid stage into 

 which these so often collapse, bear witness. 



This view at once demonstrates the thorough unity and natural- 

 ness of the Protista, and affords a basis for their classification into 

 series corresponding to the stages of the life-cycle. In the Palmel- 

 laceae or Schizomycetes the resting and motile stages are almost 

 equally prominent, while in the Desmids and Diatoms and the Sac- 

 charomycetes the encysted stage predominates. The Protoplasta, the 

 Foraminifera, the Heliozoa, and the Eadiolaria, are of course re- 

 ferable to the preponderatingly amoeboid type, while the Infusoria 

 represent the ciliated. The Myxomycetes, far from having any 

 relations to the fungi, stand on the whole nearest to the Moneron or 

 Protomyxoid type, despite the excessive differentiation of their plas- 

 modial stage." 



Mr. Geddes proceeds to point out that an intimate connection exists 

 between the changes undergone by such cyclical forms as those referred 

 to, and the conditions under which they live ; " the amoeboid state, as 

 every observer knows, varies extremely with food and temperature." 

 The morphological importance of cellulose, he cogently indicates, 

 has been greatly over-estimated ; and it is not surprising to find it 



