448 TRANSACTIONS OP SECTION D. 



must confess myself still a whole-hearted chromatinist. But l)efoie I cousidei' 

 this point I may refer briefly to some other speculations that have been put 

 forward ^Yith regard to the nature of the earliest form of life. It is manifestly 

 quite impossible that I should undertake here to review exhaustively all the 

 theories and speculations with regard to the origin of life and the first stages in 

 its evolution that have been put forward at different times. I propose to limit 

 myself to the criticism of certain theories of modern times which, recognising 

 the fundamental antithesis between chromatin and cytoplasm, regard these two 

 cell-constituents as representing types of organisms primitively distinct, and 

 suggest the hypothesis that true cells have arisen in the beginning as a process 

 of symbiosis between them. Boveri, whose merits as a cytologist need no 

 proclamation by me, was the first I believe to put forward such a notion ; he 

 enunciated the view that the chromosomes were primitively independent 

 elementary organisms which live synibiotically with protoplasm, and that the 

 organism known as the cell arose from a symbiosis between two kinds of simple 

 organisms, ' Monera."^ 



A similar idea lies at the base of the remarkable and ingenious speculations 

 of Mereschkowsky,"^ who assumes a double origin for living beings from two 

 sorts of protoplasm, supposed not only to differ fundamentally in kind but also 

 to have had origins historically distinct. The first type of protopla.sm he 

 terms mycoplasm," which is supposed to have come into existence during 

 what he calls the third epoch '" of the earth's history, at a time when 

 the crust of the earth had cooled sufficiently for water to be condensed upon 

 it, but when the temperature of the water was near boiling-point ; consequently 

 the waters of the globe were free from oxygen, while saturated with all kinds 

 of mineral substances. The second type of protoplasm was amoeboplasm, the first 

 origin of which is believed to have taken place during a fourth terrestrial epoch 

 when the waters covering the globe were cooled down below 50° C, and con- 

 tained dissolved oxygen but fewer mineral substances. Corresponding with the 

 differences of the epoch and the conditions under which they arose, 

 Mereschkowsky's two types of protoplasm are distinguished by sharp differences 

 in their nature and constitution. 



Mycoplasm, of which typical examples are seen in bacteria, in the chromatin- 

 grains of the nucleus and the chromatophores of plant-cells, is distinguished 

 from amoeboplasm, which is simply cytoplasm, by the following points. (1) 

 Mycoplasm can live without oxygen, and did so in the beginning at its first 

 appearance when the temperature of the hydrosphere was too high for it to 

 have contained dissolved oxygen ; only at a later period, when the temperature 

 became low enough for the water to contain oxygen in solution, did some of 

 the forms begin to adapt themselves to these conditions, and became secondarily 

 facultative or obligate aerobes. Amoeboplasm, on the other hand, cannot exist 

 without a supply of oxygen. (2) Mycoplasm can support temperatures of 

 90° C. or even higher; amoeboplasm cannot support a temperature higher than 

 45° C. or 50° C. (3) Mycoplasm is capable of building up albumins and com- 

 jDlex organic substances from inorganic materials ; amoeboplasm is incapable of 

 doing so, but requires organic food. (4) Mycoplasm has restricted powers of 

 locomotion and is incapable of amoeboid movement, or of forming the con- 

 tractile vacuoles seen commonly in amoeboplasm. (5) Mycoplasm, in contrast 

 to amoeboplasm, is rich in phosphorus and nuclein. (6) Mycoplasm is extra- 

 ordinarily resistant to poisons and utilises as food many substances that are 

 extremely deadly to amoeboplasm, such as prussic acid, strychnine, and morphia. 



" Fide Vejdovsky, l-c. I have not had access to the work of Boveri, in 

 which he is stated to have put forward these ideas. 



" Mereschkowsky, C, ' Theorie der zwei Plasmaarten als Grundlage der 

 Symbiogenesis, einer neuen Lehre von der Entstehung der Orgamsmen.' Biol. 

 Centralhlatt, xxx. 1910, pp. 278-303, 321-347, 353-367. 



" The term mycoplasm used by Mereschkowsky must not be confounded 

 with the similar word used by Eriksson and other botanists in reference to the 

 manner in which Rust-Fungi permeate their hosts. 



" In the first epoch the earth was an incandescent mass of vapour ; in the 

 second it had a firm crust, but the temperature was far too high to permit of 

 the condensation of water vapour upon its surface. 



