INTRODUCTORY 11 



plant as to call a slime-mould an animal because in one stage of its 

 history it resembles an amoeba. The total life of an organism in any 

 case must be taken into account.^ At the outset plants and animals 

 are alike ; there is no doubt about it ; they differ in the course of their 

 life-histories. The Plasmodium is the vegetative phase of the slime- 

 mould. It needs no cell-walls of cellulose, no more than do the 

 dividing cells of a lily-endosperm ; both are nourished by organic food 

 and resort to walls only as conditions change. The possession of walls 

 is an indication of some maturity. In the slime-mould the assumption 

 of walls is indeed delayed. Walls at length appear and when they. 

 do come they are like those of the lily; they are cellulose. The 

 myxomycetes may be regarded as a section of the organic world in 

 which the forces of heredity are at a maximum whatever those forces 

 may be. Slime-moulds have in smallest degree responded to the stim- 

 ulus of enviroment. They have, it is true, escaped the sea, the fresh 

 waters in part, and become adapted to habitation on dry land, but 

 nothing more. It is instructive to reflect that even in her most highly 

 differentiated forms the channel which Nature elects for the trans- 

 missal of all that heredity may bestow, is naught else than a minute 

 mass of naked protoplasm. Nature reverts, we say, to her most an- 

 cient and simple phases, and heredity is still consonant with apparent 

 simplicity ; apparent we say, for as becomes increasingly evident, noth- 

 inging that lives is simple ! 



The fact is the Myxomycetes constitute an exceedingly well-defined 

 group, and the question of relationship in any direction need not much 

 perplex the student. Least of all is the question to be settled by any- 

 body's dictum, which is apt to be positive inversely in proportion to 

 the speaker's acquaintance with the subject. No one test can be 

 applied as a universal touchstone to separate plants from animals. 



1 Researches of Olive, Trans. JFis. Acad. Set., Arts and Let., XV., Pt, 2, p. 

 771, and of Jahn, Ber. d. Deutseh Bot. Ges. XXVI., p. 342, and XXIX., p. 231, 

 demonstrate synapsis, and accordingly some form of alternation among the 

 slime-moulds. From the protracted and painstaking investigation of the Ger- 

 man author it appears that in Didymium at least, and probably Badliamia 

 synapsis immediately precedes spore-formation as in Ceratiomyxa; that the 

 amoeboid issue of the spores are haploid; the nuclei of the plasmodium, 

 diploid; that the ordinary vegetative plasmodium is accordingly sporophytic. 

 That is, the sporophytic phase is dominant, as in higher plants. 



