1899] WHAT IS LIFE ? 263 



pendent of chance, as the combination of compounds peculiar to each 

 individual leads to the formation of a new environment consisting of 

 complex carbon compounds, which in their turn, by acting on the 

 world at large, so modify the latter as to make it directly assimilable 

 by the nucleus. The nucleus in its turn forms the organic environ- 

 ment or cell-plasm by which it is kept in existence." 



Dr. Mann calls this an " interpretation of life," but it seems to 

 us rather dull. It is a description, and not a very lucid one, of one 

 of the characteristics of the chemical changes observed in organisms, 

 rather than a re-statement in simpler terms, which is the only scientific 

 interpretation we know of. But some of Dr. Mann's paragraphs are 

 more luminous. " In a cell we have a great many comparatively 

 simple compounds, which only collectively form the protoplasm. What 

 constitutes life is the presence of a number of such ' organic ' com- 

 pounds, capable of mutually reacting on one another, and thereby 

 giving rise to new compounds which, because of their origin, have no 

 further chemical interaction, and which therefore will form a com- 

 paratively stable mantle round the unstable or active groups which 

 gave rise to them." 



Thus the cytoplasm is a new environment created between the 

 chemically active groups (chiefly nuclear) and the world at large. 

 It has the functions — (a) of elaborating food, (b) of protecting the 

 nucleus from deleterious influences, and (c) of attracting food to the 

 cell, or of moving the cell towards food. But what, after all, is life ? 



Cycadofilices. 



Ix a paper read before the Royal Society on January 26, Dr. D. H. 

 Scott, F.R.S., gave an account of the structure of a new representative 

 of a group of Palaeozoic plants known as Cycadofilices. The plants 

 included under this head are among the most interesting of all fossil 

 types, as they furnish very important evidence as to the lines of 

 evolution of both ferns and cycads. Dr. Scott has recently had an 

 opportunity of investigating a large number of specimens of a new 

 species of the genus Mcdullosa, discovered by Messrs. Wild and Lomax 

 in the Ganister beds (Lower Coal-Measures) of Lancashire. This first 

 British example of the genus has been named MedvMosa anglica. It 

 differs in several points from the continental species, and adds some 

 valuable facts to our knowledge of the Medulloseae. 



The stem — measuring about 7 cm. in diameter — was thickly 

 clothed with the large leaf-bases of compound fronds, bearing ultimate 

 segments of the form long familiar in the common Palaeozoic genus 

 Ahthopteris; and branched roots were given off in vertical series between 

 the confluent bases of the leaf-stalks. In habit the plant must have 

 borne a close resemblance to some recent tree-ferns. 



