November 21, [918 



NATURE 



239 



infection's from the character of the eggs in the faces. 



|i.. Leipei stated that, by examination of the fasces 



livinp animal, the extent anil specific nature of 



helminthic infections could be accurately deter- 



,1, and tin' method hail been applied successfully 



tice in the case of man, rabbit, dog, 



! \\. is apparently capable of indefinite 



extension. The eggs of parasitic worms were con- 

 stant in character and of great systematic import- 

 ance. The ground-plan of the eggshell indicated the 

 genus, or even subfamily, to which the parasite 

 belon diffi rences n ere found in slight 



but constant peculiarities in relative length and 



Ith, anil in the conformation of excrescences on 

 the surface of the shell.— Dr. R. T. Leiper : The 

 "new" rabbit disease. Examination of a large 

 numb., of rabbits shows that the chief cause of mor- 

 tality is a coccidial invasion of the intestinal wall or 

 of tin- lining of the bile-ducts. According to Fantham 

 others, the causal agent in both types of disease 

 is Eimeria stiedae, but Dobell holds that the intes- 

 tinal lesion is due to a distinct species. In many 

 cases changes in the liver attributed to coccidiosis 

 win- the result of infection with Cysticercus piri- 

 formis, the larval stage of tin: dog tapeworm (Taenia 

 serrata). Large swellings in the region of the head 

 and neck, suspected to be cancerous, were due to 

 Coenusus seriaJis, the larva of the dog tapeworm 

 Taenia coenurus. Of relatively small economic im- 

 portance are infections with the threadworm (Oxyuris 

 ambiguus) and the tapeworm (Ctetwlacnia leuckarti). 

 There is some evidence that a bacterial infection mav 

 occasionally be the cause of death. The coccidial 

 infections pass from infected to healthy animals 

 through the fseces. When freshly passed, the coccidial 

 oocysts are not infective. Thev only become so after 

 a period of delay, in which certain developmental 

 changes take place. These changes proceed more 

 dly in dry than in wet faeces. Prevention depends 

 matic periodical removal and destruc- 

 tion b> burning of all pellets and contaminated 

 bidding, and the use of some fluid which will destroy 

 such oocysts as remain in the hutch. Although several 

 of coccidial infection in man have l»en recorded, 

 Dobell maintains that in none of these cases is 

 Eimeria stirdac the causal agent. There would 

 . to be no risk- of inf.. lion to man. 

 The cvstic stages of the tapeworms of the dog npnear 

 to occur chiefly in 'hose rabbits fed with dandelions 

 and other gri • n stuffs collected from the roadsides, 

 i.ei is especialh liable to contamina- 

 of dogs which have acquired their 

 . • ating un ooked i .ibi.it offal. 

 I.innean Socieh, Novembi r 7. s i David Prain, presi- 

 . in the chair. — The late Dr. E. \. Newell Arber and 

 F. YV. I.awfield : The external ..f the stems 



of Catamites, with a revision of the British species 

 of Calamophloios and Dictvocalamites of Upper Car- 

 This paiier deall with the externa! 

 morphology of Calamites and their reception into the 

 new form genus — Calamophli ously erected 



by Dr. Arber. No systematii endeavour to differen- 

 tiate specimens showing the external surfaces of 

 has previously bi ' although the 



as long overdue. Bv further inquiry it was 

 hop. d the various species of Calamophloios 



I to pith-casts, and a 

 1 d alreadv been made in this paper. — Mrs. 

 \rhcr : Tie lution. It apt. ear i 



il. that a structure or organ once lost 

 in the course of phytogeny '.an never be regained; if 



the organism afterwards has ision to replace it. 



it cannot be reproduced, hut must be constructed 

 h in some different mode. Tin- author proposes 



NO. 2560. VOL. T02" 



io term this principle the "law of loss." This law- 

 is obviously not susceptible of direct proof, but an 

 attempt is made to show that, if used as a working 

 hypothesis, it throws light on a number of structural 

 features the interpretation of which presents difficul- 

 ties on oili.r theories. Some time after the author 

 had deduced the "law of loss" from a comparative 

 study of living plants, she learned that zoologists had 

 arrived at very similar conclusions regarding 

 vertebrates from a study of their palaeontological his- 

 tory. Dollo's "law of irreversibility" covers much the 

 ground as the "law of loss." The fact that 

 the satin- principle lias been recognised independently 

 for plants and for animals — in one case through a 

 study of comparative morphology, and in the other 

 through a consideration of actual historical evidence 

 derived from fossil records — seems to be an indica- 

 tion of the validity of the law. 



Mathematical Society, November 14. — Annual meeting. 

 — Prof. H. M. Macdonald (retiring president) and after- 

 wards Mr. J. E. Campbell (new president) in the 

 chair. — Prof. H. M. Macdonald (retiring president) : 

 Presidential address.— Prof. M. J. M. Hill : The use of 

 a property of Jacobians to determine the character of 

 any solution of an ordinary differential equation of the 

 first order, or of a linear partial differential equation 

 of the first order.— Prof. H. J. Priestley: The roots of 

 1 certain equation in spherical harmonics. — J. Hodg- 

 kinson : A detail in conformal representation. — T. A. 

 Broderick ; The product of semiconvergent series. — Dr. 

 YV. P. Milne : A simple condition for co-apolar 

 triangles. 



Edinburgh. 

 Royal Society, October 28.— Dr. Home, president, in 

 the chair.— The president delivered an opening ad- 

 dress on the endowment of scientific and industrial re- 

 -. arch.— Dr. T. S. Patterson and Mr. K. L. Moudgill : 

 Researches in optical activity : the temperature rota- 

 tion curves for the tartrates at low temperatures. 

 By the piecing together of evidence of different kinds, 

 general temperature-rotation curves for the tartrates 

 have been arrived at. These graphs show- maxima 

 and minima, and also a region of intersection. The 

 influence of temperature changes, of change of sol- 

 vent, of change of concentration, or of change of 

 1 .institution appears to be to displace the whole series 

 of graphs in one direction or the other, with, of 

 course, accompanying minor alterations. The present 

 paper describes the investigation of the temperature- 

 rotation curves for tartrates at the low temperature 

 end of the diagram, where a deep minimum is shown 

 to exist. Miss \I. G. Haseman : Amphicheiral knots. 

 This is a continuation of a former communication on 

 amphicheiral knots, and contains, among other things, 

 the description of two amphicheiral knots of twelve 

 i itersections which had formerly escaped notice.— Dr. 

 C. (;. Knott: Further note on the propagation of 

 earthquake waves. Following up the investigations 

 given in a former paper (see Nature, Februarysi, 

 ,,,S). the author directed attention to the curious 

 Millions form of seismic r.avs which emerge at an 

 aniiil distance of from 6o°-8o° from the epicentre, 

 reach a depth of about a quarter of the 

 earth's radius. This sinuositv proves that in the 



bourh 1 of that depth the velocity of propaga- 



after increasing with the depth, begins to 

 diminish, but Ibis diminution does not seem to con- 

 tinue to greater depths. 



Manchester. 



I.itcnirv and Philosophical Society, October 29.— Mr. 



W Thomson, president, in the chair. Prof. C. A. 



Edwards: The hardness of metals. Prof. Edwards 



in account of various methods of making hard- 



