PRRSIDKNTTAL ADDRESS. 447 



to have discovered, but which have never been found again by any other 

 naturalist. These organisms, as described by Haeckel, were by no means such 

 as the modern inicroscopist would call minute ; on the contrary, tliey were rela- 

 tively large, and some of the forms added to the ilonera by Haeckel's con- 

 temporaries might even be termed gigantic, as, for example, tlie supposed 

 organism Udt/iijljiiis, discovered in the bottles of the (Jliulhmjtr Expedition, 

 which was believed to cover large areas of the floor of the ocean with a layer 

 of primordial protoplasm, but which proved finally to be a preeipitation by 

 alcohol of the gypsum hi sea-water. 



The theory of plasson and of the cytodes of Haeckel may be considered first 

 from the purely speculative standpoint of the origin of the living substance, a 

 problem with which I wish to become entangled here as little as possible, since 

 it is my object to confine myself so far as possible to deductions and conclusions 

 that may be drawn from known facts and concrete data of observation and ex- 

 periment. If, however, we postulate a chemical evolution of protoplasm, and 

 believe that every degree of complexity exists, or at least has existed, between 

 the simplest inorganic compounds and the immensely complicated protein- 

 molecules of which the living substance is composed, then no doubt chemical 

 compounds may have existed which in some sense were intermediate in their 

 properties between the two constituents, cytoplasm and chromatin, found in all 

 known samples of the living substance of organisms. In this sense and on such 

 a hypothesis, a substance of the nature of plasson may perhaps be recognised 

 or postulated at some future time by the biochemist, but this is a subject which 

 I am quite incompetent to discuss. To the modern biologist, wlio can deal 

 only with living things as he knows them, Haeckel's plasson must rank as a 

 pure figment of the imagination, altogether outside the range of practical 

 and objective biology at the present time. All visible living things known and 

 studied up to the present consist of protoplasm, that is to say, of an extremely 

 heterogeneous substance of complex structure, and no living organism has been 

 discovered as yet which consists of homogeneous structureless albuminous sub- 

 stance. Van Beneden, who is responsible for the word plasson, though not for 

 the cytode-theory, was under the impression that he had observed a non- 

 nucleated homogeneous cytode-stage in the development of the gregarine of the 

 lobster, Gregarina (Porospora) rjigantea. Without entering into a detailed 

 criticism of Van Beneden's observations upon this form, it is sufficient to state 

 that the development of gregarines is now well known in all its details, and that 

 in all phases of their life-cycle these organisms show the complete cell-structure, 

 and are composed of nucleus and cytoplasm. JMoreover, all those organisms 

 referred by Haeckel to the group ^Monera which have been recognised and 

 examined by later investigators have been found to consist of ordinary cyto- 

 pla.sm containing nuclei or nuclear substance (chromatin). In the present state 

 of biological knowledge therefore, the jMoneni as defined by Haeckel must be 

 rejected and struck out of the systematic roll as a non-existent and fictitious class 

 of organisms. 



Since no concrete foundation can be found for the view that cytoplasm and 

 chromatin have a common origin in the evolution of living things, we are brought 

 back to the view that one of them must have preceded the other in phylogeny. 

 The theories of evolution put forward by Haeckel and his contemporaries, ff we 

 abolish from them the notion of plasson and substitute for it that of ordinary 

 protoplasm, would seem to favour rather the view that the earliest forms of life 

 were composed of a substance of the nature rather of cytoplasm, and that the 

 nuclear substance or chromatin appeared later in evolution as a product or 

 derivative of the cytoplasm. I have myself advocated a view diametrically 

 opposite to this, and have urged that the chromatin-substance is to be 

 regarded as the primitive constituent of the earliest forms of living organisms, 

 the cytoplasmic substance being a later structural complication. On this 

 theory the earliest form of living organism was something very minute, 

 probably such as would be termed at the present dav ' ultra-microscopic' After 

 1 ha,d urged this view in the discussion on the origin of life at the 

 Dundee Meeting of the British Association in 1912 a poem appeared in 

 launch, dividing biologists into ' cytoplasmists ' and ' chromatinists." 



" Vol. cxliii. p. 245. 



