84 



NA TURE 



[XOVE.MUEK 19, 1908 



also bipolar, and that the southern Echiurus chilensis and 

 Priapidoides australis have their counterparts in . the 

 northern E. unicinclus and P. typicus. Prof. R. Blanchard 

 describes six new species of leeches belonging to the genera 

 Trachelobdella (i), Helobdella (4), and Seniiscolex (i). 

 Mr. Frank E. Beddard deals with a large number of new 

 OIigocha;ta. Thus he establishes a new genus of 

 Limicols, Hesperodrilus, with four species, and among 

 Terricolae he describes thirteen new species of Acanthodrilus 

 and eight of Microscolex. He regards the south of South 

 .America as the headquarters of these two genera, while 

 the Geoscolecida; and the genera Kerria and Ocnerodrilus 

 arf as distinctively northern. The collection included eight 

 Lumbricida?, which are all European species, and probably 

 imported. Dr. Michaclsen also makes a report on the 

 Terricolse, adding some new forms and adjusting the 

 names of others in accordance with his system of classifi- 

 cation. Dr. H. Ude deals with the Enrhytraeidje, and 

 points out that the genera represented in the sub-Antarctic 

 region, e.g. Enchytra;us, Pachydrilus, and .Marionina, are 

 familiar European or even boreal genera. This indicates 

 the world-wide distribution of an ancient fresh-water fauna. 

 But, curiously enough, the genus Mesenchytra;us is not 

 represented at all in the .Antarctic region. 



Prof. Ernst Ehlcrs reports on the .Magellan Polychaeta — 

 eighty-five species (thirty-six new) in fifty-five genera — and 

 gives an interesting description of the general features of 

 the polycha^t fauna, such as the strong representation of 

 Syilids and Phyllodocida". The following species occur in 

 the boreal and notial regions, but not in the intermediate 

 tropical and subtropical seas : — .Xcphthys loiigisciosa, 

 Glycera americana, Scolecolepis vulgaris, .irenicola 

 assimitis, and \'otnmastus latericcus. How this " bi- 

 polarity " is to be accounted for Prof. Ehlers does not 

 say. 



Dr. von I.instow has some very remarkable facts to 

 relate reg.-irding nematodes. Thus Ascaris osciilata of 

 northern Fissipedia occurs also in exclusively .Antarctic 

 forms, and .l.scaris adiiiua occurs in northern and southern 

 fishes the habitats of which in no way overlap. From 

 cases like these, and from the character of the free-living 

 nematodes, von Linstow argues that in past ages the 

 conditions of life -and evolution must have been moi'c 

 uniform over the earth, and the occurrence of types much 

 more widespread. Dr. O. Steinhaus points out that four 

 species of Chastognatha are common to the far north and 

 the far south. .As to nemerfeans. Prof. O. Burger directs 

 attention to the complete absence of Protonemertini from 

 southern waters, and to the occurrence of Carinonia 

 patagonica in the Straits of .Magellan — its only known 

 congener being the rare C. armaiidi of the British coast. 

 He thinks that the resemblance of the boreal and notial 

 nemerteans is undeniable, so long as we fix our attention 

 on genera. 



Prof. Lonnberg remarks on the close resemblance 

 between three southern cestodcs and Scandinavian species. 

 It is the similarity of ho.st that counts. The northern host 

 of Bothridiotaenia crostris is a gull or a fulmar ; the 

 southern host of the same is a penguin. Prof. Max Braun 

 establishes a new genus of trematode, Lophocotyle, which 

 ranks among the .Monocotylida? ; Dr. Rudolf von Ritter- 

 Zahony establishes two new genera of polyclads ; and 

 Prof. L. Bohmig describes three new rhabdoccclids and 

 five new tridads. 



It should be noted that most of the authors have in- 

 creased the value of their contributions by including in 

 their survey all the forms recorded from' the Magellan 

 region. As regards the question of " bipolar " distribution, 

 to which most of them refer, the impression left on a 

 reader's mind is that it is very difficult to generalise. It 

 appears that the state of affairs differs in regard to 

 different sets of animals. In some cases, e.g. holo- 

 thurians,^ the dissimilarity of boreal and notial forms is 

 more striking than the resemblance ; in other cases, e.g. 

 Bryozoa, there is a marked resemblance as to the genera 

 represented at the two poles, but this does not extend to 

 any identity of species ; in a few cases, e.g. Gephvrca, the 

 same species occur north and south, but some of the 

 instances of this kind have to be discounted when the 

 species in question {e.g. of Cirripedia) are cosmopolitan. 



NO. 2n';S, vol.. 7<j] 



BOTANY AT THE BRITISH ASSOCIATION. 

 'THE proceedings of Section K at Dublin, under the 

 presidency of Dr. F. V. Blackman, were rather 

 above than below the average standard of quality, and 

 were characterised by more homogeneity than is usually 

 the case, a large proportion of the papers dealing with 

 certain aspects of physiological botany. Several of these 

 dealt with those fields of investigation in which progress 

 at present consists in the application of physico-chemical 

 principles and quantitative methods to the experimental 

 analysis of complex physiological phenomena into their 

 component processes and factors. 



The presidential address (N.iture, October i, vol. Ixxviii., 

 p. 556), which was entitled " The Manifestations of the 

 Principles of Chemical Mechanics in the Living Plant," 

 dealt with this aspect of physiology, and urged the view 

 that in some cases the internal metabolic changes of the 

 organism which follow external changes should be re- 

 garded, not as reactions of protoplasm to stimulation, but 

 as inevitable alterations of metabolic reaction-velocity. 



Physiological Papers. 



The death of individual cells as brought about by ( homical 

 poisons or high temperatures is a complex phenomenon, the 

 experimental quantitative investigation of which leads to 

 important biological conceptions. Two papers were com- 

 municated on this subject after the delivery of the presi- 

 dential address. The first, by Miss Harriette Chick, dealt 

 with the death-rale of bacteria under the action of dis- 

 infectants. When a crowd of similar bacteria are treated 

 with any disinfectant they die off at such a rate that the 

 " number surviving " after successive intervals of time fall 

 into a logarithmic curve. The process of killing is thus 

 continuous, and there is no definite time of exposure which 

 can be said to be fatal. The killing goes on in a way that 

 recalls the progress of a monomolecular reaction according 

 to the " law of mass." It is shown that the different 

 times of resistance of the bacteria are not due to permanent 

 differences between the individuals, but that these differ- 

 ences are temporary and possibly phasic. Viewed in this 

 way, the rate of killing is a phenomenon of reaction- 

 velocity, and it is found that increase of temperature 

 accelerates the reaction-velocity of disinfection just as it 

 does that of a chemical reaction. 



This paner was followed by one by Miss Nora Darwin 

 and Dr. V. F. Blackman, dealing with the death-rate of 

 cells of higher plants in llttal conditions. When it is 

 realised that bacteria die off logarithmically under uniform 

 unfavourable conditions, it becomes at once interesting to 

 determine whether the cells of a tissue of a higher plant 

 die in the same independent way, or whether their closer 

 protoplasmic connection leads to their behaving all alike. 

 Fxperimenis on this point are being carried out with strips 

 of potato, fuchsia stamens, and other organs, using the 

 shortening of the tissue resulting from loss of cell-turgor 

 on death as an indication of the progress cf the death- 

 rate. .An optical lever was used to record the shorteninsj, 

 and submersion in hot water as the fatal condition. The 

 cells of the tissue appear to behave like a number of 

 bacteria, and to die off progressivelv and Iog;arith'iii<-allv, 

 but this interpretation has yet to be firmlv ei'iblished. 

 Seeds submersed in w.Tter at 42° C. to 50° C. exhibit 

 clearly a logarithmic death-rate. 



Other physiological oapers were communicated on Thurs- 

 day by Prof. H. H. Dixon, on the influence of living cells 

 on the transpiration current, and bv Prof. Bose. on tli" 

 mechanical and electrical responses of plants. Prof. Dixon 

 described experiments to show that there is no evidence 

 of vital activity as a contributory factor in raisinar the 

 transpiration current in a branch. The rate of trans 

 mission of water in a branch from above downwards was 

 found to be the same bi^fore and after killing by ste.i-" 

 rr picric acid. The fading of leaves on a steam-kill"d 

 branch is shown to be directly due to n noison libe'-n<m1 

 into the transpiration current by the dead cells, and '■= 

 not to be t.'d^en as evidence th.nt some preexisting \''t.''l 

 raisin"- force has been extino^uished bv the killing. 



Prof. Rose rtnve ,n c,i.-.7-.r-iry of his views on nlnnt-'o- 

 sponses as expounded in bis recent bonks. His paper was 



