November 13, 1902] 



NA TURE 



43 



the same conception and extends it in a thesis for the doctorate. 

 The cytoplasm of a dividing cell is differentiated as the site of a 

 field of force ; the spindle with its asters is the visible embodi- 

 ment of the lines of force ; the centrosomes occupy the poles, 

 that is the points of maximum potential and of physical equi- 

 librium, though it is not legitimate to say that they are them- 

 selves either the sources or the causes of the molecular stresses 

 and strains. Where the centrosome expands into a large zoned 

 astrosphere, as in the eggs of Rhynchelmis or Unio, the zones 

 correspond to equipotential surfaces. It has been objected to 

 such views that they will not explain multipolar figures, such as 

 often occur in nature : but a tripolar figure can be formed in the 

 above electric working model by introducing a third terminal put 



Fig. 



to earth ; while a quadripolar spindle can be reproduced by a 

 magnetic model where iron-filings group themselves under the 

 action of four poles alternately arranged at the consecutive angles 

 of a square. But perhaps the most convincing illustration is sup- 

 plied by two consecutive figures ; the one (Fig. i) is a geometrical 

 construction to represent the plane section of a field of force 

 passing through the poles, and displaying the system of equi- 

 potential zones and lines of force, when the charges at the poles 

 are + 5 and - 3 respectively ; and the other (Fig. 2) is the de- 



FlG. 



lineation of an unequal mitosis in the connective tissue of a 

 salamander-larva copied from F. Reinke. 



The splitting of the chromosomes and the repartition of their 

 twin moieties are referred to the same forces, which he terms 

 "■ karyokinetic" not to prejudge their real nature. He suggests 

 that in direct or amitotic divisions of the cell and nucleus the 

 same forces are at work, although nd material presentment of 

 the lines of force is seen. 



The whole of this part is admirably worked out : it is quite 

 free from those mathematical short-cuts, which are, indeed, indis- 

 pensable for the rapid daily work of the physicist, but which 

 Faraday, the great investigator of polar forces, was able to dis- 

 pense with, and which are for the most part incomprehensible 

 if not revolting to the biologist. 



NO. 1724, VOL. 67] 



Gallardo regards heredity as the transmission from cell to 

 cell of the power to develop such forces in due course. That 

 these forces are neither electric nor magnetic is certain. - It is 

 unlikely that Blitschli's suggestion that they are osmotic is 

 adequate, though doubtless osmosis does play a part in the pro- 

 cess. Gallardo is content for the moment to regard them as 

 " vital " forces, avowing that he is so far a vitalist as to admit 

 that the phenomena of living beings present problems and cha- 

 racters not found in inorganic or dead groupings of matter. 

 He does not, however, accept J. Reinke's " dominant " 

 hypothesis. 



We ourselves greet this pamphlet the more cordially as em- 

 bodying ideas that we have held for years — nay, have attempted 

 to work out. The task, however, could only be accomplished 

 by one who possessed a solid grasp of modern physical science 

 as well as of biological fact. We may note that the device we 

 have adopted for modelling in three dimensions the karyokinetic 

 figures — a glass trough of glycerine in which are suspended the 

 finest iron-filings, levigated in alcohol — will be found useful by 

 the physicist ; for by moving it from place to place in a magnetic 

 field he can render the courses of the lines of force visible, and 

 map them out in space for himself or his students. 



Marcus Hartog. 



THE RABBIT PEST IN AUSTRALIA. 1 



TT was hoped and expected that the long-continued drought 

 ^ which has prevailed throughout eastern Australia for the 

 last six years would at least have had a good influence in sub- 

 duing the rabbit pest, but such does not seem to have been the 

 case. The rabbits, like all other living animals, have suffered 

 severely in certain districts, but on the least mitigation of the 

 drought they quickly recover themselves, and become as numerous 

 and as destructive as ever. Large tracts of country formerly able 

 to maintain sheep have been abandoned, we are told, on account- 

 of the rabbit pest, and have gone to waste in consequence of the 

 futility of the various schemes that have been tried for the 

 mitigation of this frightful evil. 



In these circumstances, Mr. William Rodier, of Tambua 

 Station, Cobar, New South Wales, has done well to reprint the 

 pamphlet on this subject to which we directed attention on 

 a former occasion (Nature, March 21, 1SS9), and to explain 

 more fully the very simple and efficacious method by which he 

 proposes to deal with the rabbit pest. Had the scheme put for- 

 ward by Mr. Rodier been adopted when it was first suggested, 

 we do not doubt that the success which it has met with on his 

 own station would have followed it elsewhere. But, as we all 

 know too well, the prophet has little honour in his own country, 

 and, instead of following Mr. Rodier's excellent advice, the 

 authorities have tried various other schemes that have in many 

 cases only had the effect of augmenting the evil. 



Mr. Rodier's plan for combating the rabbit pest is very simple. 

 It is based on the well-known law of nature that polygamy is 

 favourable to the increase of offspring and polyandry is 

 unfavourable. Rabbits usually live in a polygamous state. One 

 male impregnates a number of females and produces a large 

 offspring. Mr. Rodier proposes to convert this polygamy into 

 polyandry by catching the rabbits alive and killing all the 

 females, while all the males are turned out again. If this is 

 done, the male rabbits become more numerous than the females,, 

 harass the females by their constant attentions and injure their 

 powers of breeding. Thus the offspring becomes continually 

 less numerous. That this result will follow is illustrated by the 

 case of public women, who seldom bear children and never 

 produce large families, and by other facts well known to science. 



The ordinary course pursued in trapping rabbits, in which 

 all that are caught are killed, so far from diminishing the evil 

 is much more likely to increase it. The great majority of the 

 rabbits captured are sure to be males, because the male rabbits 

 have the habit of congregating in certain spots called " buck- 

 heaps." In these spots they are easily caught by the trappers, 

 who are, of course, only anxious to kill as many as possible and 

 to obtain the fees offered for their destruction by the Rabbit 

 Acts. Thus the males become diminished in numbers and the 

 breed becomes increased. Various other modes of combating the 

 rabbit pest have been tried in Australia, but all alike have proved 

 to be failures. Poisons of different descriptions have been much 



1 " The Rabbit Pest in Australia, its Cause and its Cure." By W. Rodier, 

 Pp. 16. (Sydney, 1902.) 



