234 NATURAL SCIENCE. qct., 



hypothesis. " If anyone is incHned to reject my explanation because 

 it leads into the obscureness of the germ-plasm, of the structure and 

 vital processes of which we can learn nothing directly, let him 

 remember that the origin of the variations cannot be found anywhere 

 else, and that we must, therefore, form some conception of the germ- 

 plasm if we wish to penetrate deeper into the riddle of phylogenesis 

 at all. I simply submit my conception of the structure of the germ- 

 plasm as a working hypothesis. Let it be tested by facts ; let it be 

 improved according to the results thus attained ; let it be overthrown 

 should it in the end prove unsatisfactory ; but do not let us say in 

 advance that such a thing cannot be ! " 



Many writers have confused the actual existence of a germ- 

 plasm with Weismann's hypothetical conception of its structure. 

 No one having the smallest acquaintance with the results of modern 

 embryology doubts that there is a material contributed by each 

 parent in parts of equal valency. In the same fashion as the 

 properties of an amoeba are resident in its protoplasm, the inherited 

 qualities of an organism are resident in the portion of germ-plasm 

 from which it sprung. Dr. Oskar Hertwig, who has been the most 

 weighty critic of Weismann's hypotheses, agrees with Weismann, 

 and, indeed, with everyone else worth considering, that the germ- 

 plasm must be a material of extraordinary complexity. Weismann 

 has endeavoured to interpret the observed phenomena of heredity into 

 terms of a hypothetical structure of the germ-plasm. As he says 

 himself, his interpretation may have to be enormously modified or 

 abandoned as knowledge increases. But to object to it, as it seemed 

 to us and to Weismann himself that Mr. Herbert Spencer objected 

 to it, that it cannot solve a number of problems of heredity that as 

 yet are insoluble upon any hypothesis, is special pleading for a 

 verdict, and not helping to advance thought. 



Life-History of the Foraminifera. 



In Natural Scienxe for November, 1894, we called attention to 

 the abstract of a paper by Mr. J. J. Lister on the above subject. The 

 full paper is now before us (Philosophical Transactions, vol. clxxxvi.) 

 and is illustrated by four plates dealing with Polystomella crispa, 

 Calcavina hispida, Rotalina beccarii, Orbitolitcs complanata, and Cycloclypeus 

 carpenteri. The conclusions arrived at by Mr. Lister are as follows: 

 (i) The species of Foraminifera are in a great number of cases 

 dimorphic. (2) The two forms differ from one another in the 

 following features, (a) the size of the central chamber, (b) the shape 

 and mode of growth of the chambers succeeding the megalosphere and 

 microsphere, (c) the character of the nuclei. (3) The two forms differ in 

 the frequency of their occurrence, the megaiospheric forms being much 

 more abundant that the microspheric. (4) The megaiospheric form 

 arises as a young individual already invested by a shell, which may 



