SCIENCE-GOSSIP. 



309 



extremities. It is abruptly truncate anteriorly, 

 and produced posteriorly into a sharp point ; it is 

 from 45 to 227 microns in length. The amylaceous 

 corpuscles are numerous, and elongate and rec- 

 tangular in shape. It needed no great flight of the 

 imagination to call this animal " acus " ; it truly 

 resembles a needle, the posterior extremity forming 

 a formidable point, and the contractile vacuole an 

 excellent eye. It would take a skilled sempstress 

 indeed to thread this needle. 



Phacus longicaudus, Ehr. — The body is compressed 

 and leaf-like in shape ; the posterior extremity is 

 drawn out into a sharp-pointed tail-like prolonga- 

 tion, which may equal the rest of the body in 

 length ; the cuticular surface is longitudinally 

 striated and hard, but not so hard as in some of 

 its congeners. A curious characteristic of this 

 animal is the corkscrew-like shape into which it 

 sometimes twists its body. This is not brought 

 about by any sudden movement but by a very 

 gradual process, which might possibly be due to an 

 unequal rate of growth of the ectosarc. If this 



were the case it would be analogous to the twisting 

 of the tendrils of plants, which is effected by 

 different parts of the tendril assuming in succession 

 a more rapid rate of growth. 



In other points of structure besides those above 

 mentioned, Phacus agrees fairly closely with 

 Eugtena. I found P. longicaudus in greatest 

 quantities in the dykes which drain the large 

 areas of marshland which occur on the east coast 

 of Norfolk. The length of the body is 52 to 156 

 microns. 



Phacus triquetev, Ehr. — More or less closely re- 

 sembles P. longicaudus, Ehr. It has a raised keel- 

 like elevation produced down the middle of one 

 side, its caudal prolongation is only about a 

 quarter of the length of the body, and is obliquely 

 pointed in an upward direction. It does not twist 

 itself spirally like the last species. Length of 

 body, 47 microns. 



Its favourite habitat appears to be in ponds 

 covered with duckweed. 



[To be continued.) 



AFTER DARWIN. 

 By G. W. Bulman, M.A., B.Sc. 



TT was, perhaps, but to be expected that with the 

 ■*■ loss of their captain the camp of evolution by 

 natural selection, should be divided, and that each 

 lieutenant should aspire to the rank of leader. Or, 

 to speak more appropriately, it was only natural 

 that spontaneous differences of opinion should 

 arise, and that in the ensuing struggle for existence 

 among these variations, certain should survive, and 

 finally form more or less distinct theories. This is 

 emphatically what has happened. 



In a letter to " Nature," July 30th, 189G, 

 Mr Thistleton Dyer writes: "The result is that 

 the Darwinian theory of organic evolution seems 

 hardly to have a convinced supporter left except 

 Mr Wallace. In its place we have the ' Physiolo- 

 gical Selection ' of Dr. Romanes, the ' Discontinuous 

 Variation ' of Mr. Batcson, and, last of all, the 

 extended ' Correlation Principle ' of Professor 

 Lankester." 



Even this does not exhaust the list. We must 

 add the Neo-I.amarckism of the Americans, and 

 the Nee-Darwinism, or pure Natural Selection, of 

 Weiimann and others. Each thinks his own 

 ••improvement" does away with the difficulty 

 which he naturally and rightly feels in the original, 

 and no one else quite agrees with him Still more 

 naturally doe* Dr. Wallace hold to the older view 

 as being hb own Yet even Dr. Wallace ii nol on 

 all poind an orthodox Darwinian. He has, for 

 example, rejected sexual selection, which formed so 

 wq-- riant a part of Darwin's views, and upon 



M 



which he relied so much. Dr. Wallace would also 

 bring in other factors in the evolution of the 

 higher nature of man which Darwin did not 

 acknowledge. Thus, even Darwin's co-partner in 

 the theory of natural selection has diverged ; and 

 we may, perhaps, safely assert that there is no 

 evolutionist of authority who has not wandered, 

 more or less, from pure Darwinism — meaning 

 thereby the Darwinism of Darwin himself. 



The volume before me — " Darwin and After 

 Darwin," part iii. — is an interesting example of 

 the evolution of a new variety of the parent theory. 

 This third part of Dr. Romanes' work deals with 

 the questions of isolation and physiological selec- 

 tion. It is in some respects the most important, 

 as it contains an account of Dr. Romanes' own 

 contribution to the theory of natural selection. 

 The author was led to formulate this hypothesis to 

 supplement what he felt was the insufficiency of 

 the theory of natural selection as understood by 

 I larwin and others. This, indeed, is the explana- 

 tion of most of the amended theories of evolution 

 which have from time to time appeared. Their 

 authors have all felt the difficulties of the subjei I 

 as it Stood, but all have found I lie In >le:, In dillemit 

 places. So, each having put on his patch, refuses 

 1 liat the patch of any other is at all necessary. 

 Their united testimony leaves scarcely a Bound 

 part in the original view. To the impartial 

 onlooker each is more convincing when ho is 



showing the weakness of another than when 



