Nov. 2 2, 1883] 



NATURE 



91 



SPLENIC FEVER IN THE ARGENTINE 

 REPUBLIC^ 

 *!" HE author stated that he did not think any one who had 

 worked much on the subject of splenic fever could doubt 

 that the bacilli which caused that disease were capable of 

 considerable variation in their effects on animals and man. 

 Whether this disease, which is without doubt the one which has 

 been most thoroughly investigated of all zymotic affections, gave 

 any support to the views of Dr. Carpenter was another matter, 

 but there could be no doubt that the Bacillrts anthracis can be 

 so modified by artificial means that the disease which it pro- 

 duces when introduced into animals, such as sheep and cattle, 

 varies considerably as to duration, amount of fever produced, as 

 well as to its mortality. 



That, on the other hand, this bacillus has at least a very strong 

 tendency to retain the characters which it nt present presents in 

 Europe is shown by the fact that in the Arg;entine Republic, — into 

 which the affection was introduced at least thirty years ago, 

 and where the conditions ai-e very different from those which 

 exist in Europe, — we find that the minute organism retains its 

 characteristic form and the properties with which we are so well 

 acquainted in liurope, and that the disease which it produces is 

 practically identical with the European disease. That it should 

 vary in some particulars is perhaps only to be expected, but Dr. 

 Roy preferred leaving that point to be treated of elsewhere and 

 occu]3ying the time at his disposal with an account of the obser- 

 vations which he had made as to the means of protecting from 

 the disease by means of inoculation. 



Some six months ago he had been requested by a City com- 

 pany who possess a large tract of land in the Argentine Re- 

 public, to pay a visit to their property in order to investigate a 

 disease which was causing much mortality among-t the cattle, 

 sheep, and horses, and which was affecting the employes as well 

 to a very serious extent. This disease, he found on arriving 

 at the River Plate, was splenic fever, of which the absence of 

 efficient veterinary surgeons and the general apathy of the 

 owners of stock had prevented the recognition. Having spent 

 some time in studying the characters of the disease, he pro- 

 ceeded to make observations on the be-t means of protecting 

 the stock by means of inoculation, which work was much facili- 

 tated by the liberality of the company (the " Las Cabezas 

 Estancia Company") who gave him "carte blanche" as to 

 the number of animals which he might employ for his experi- 

 ments. Having previously found, in a small series of observa- 

 tions made in this country in conjunction with Dr. E. Klein, that 

 splenic fever virus from white mice was of the proper strength 

 to protect sheep from the disease, he proceeded in the same 

 lines, employing such animals as were available to produce the 

 inoculating fluid. After a number of animals had been tried, he 

 found that the blood of Biicachas (prairie dog) which had died 

 of the disease gave satisfactory reults when used to inoculate 

 cattle and horses. It was, however, a little two powerful, as 

 I or 2 per cent, of the cattle so inoculated died. The pecuniary 

 loss entailed by this was, however, more than counterbalanced 

 by the arrest of the mortality from the natural affection. With 

 regard to sheep, greater diiSculties were encountered, and no 

 animals were found giving a virus sufficiently mitigated to cause 

 only a slight form of the disease with subsequent protection. 

 Unfortunately it was imp )s4ble to repeat on a large scile the 

 successful experiments which Dr. Roy and Dr. Klein had made 

 with virus from white mice, these animals not being obtainable. 

 Virus from field-mice and rats did not prove satisfactory. 



Under these circumstances the speaker then proceeded to 

 investigate the results obtained by artificial mitigation of the 

 bacilli in the laboratory. He first employed the method of 

 Toussaint, which consists in warming the fluid containing the 

 pathogenic organisms to a temperature of 55' C. for a period 

 varying from a half hour to one hour and a half. It was found 

 possible by this means to diminish the strength of the virus so 

 that it took longer to kill, and by graduating the duration of the 

 heating it is not difficult to obtain a virus which will only kill a 

 small percentage of the animals inoculated. Bat unfortunately, 

 in weakening the virulence of the organised poison, this process 

 weakens aUo its power of protecting from a second attack, and 

 it w'as easy to kill the animals so inoculated by subsequently in- 

 troducmg into their system strong virus which had not been sub- 

 jected to heat. This method having failed. Dr. Roy proceeded 

 to Buenos Ayres, where, in the laboratory of the " Collegia 



* Abstract of a paper read at tfie British Association by Dr. C. S. Roy. 



Nacional," which was kindly placed at his disposal, he manipu- 

 lated the virus by the method of Pasteur, w^hich consists in culti- 

 vating the virus in sterilised chicken broth at a temperature 

 of 42' — 43° C. At this temperature the bacilli grow much les 

 readdy than at one more nearly approaching blood heat. The 

 bacilli so cultivated diminish in vnulence day by day, and after 

 being cultivated for six or eight days no longer caused the death 

 of full-grown sheep, although they still killed lambs and prairie 

 dogs. 



Careful experiments with inoculating fluid prepared in this 

 manner showed that with it a slight fever could be induced 

 which suffices to protect, at least for some time, from a second 

 attack of the disease. The same objection, however, which 

 characterises the inoculating fluid prepared by Toussaint's method 

 exists, though to a less extent, with regard to Pasteur's fluid ; 

 in the case of the latter as well as the first named, the protecting 

 power is seriously diminished at the same time that the virulence 

 of the bacilli (as mdicated by the mortality) is lessened. With 

 care it is possible, however, to prepare a liquid which, while its 

 virulence has been brought sufficiently below the lethal limit to 

 insure that none of the inoculated animals succumb to the inocu- 

 lation, still retains enough protsicting power to enable the sheep 

 to resist the effects of strong virus employed some ten to fifteen 

 days after the first inoculation. Dr. Roy was, therefore, able to 

 confirm the assertions of M. Pasteur regarding the attributes of 

 his inoculating fluid in so far that it is possible effectually to pro- 

 tect sheep from anthrax by its use. titill, it was impossible to 

 overlook the fact that its employment necessitated very careful 

 graduation of the strength of the mitigated virus to the resisting 

 power of the animals inoculated. The speaker did not think 

 that the method was one which w as likely to be adopted univer- 

 sally, and he rather looked forward to the general acceptation of 

 some inoculating fluid which had been mitigated by cultivation 

 in the bodies of some animal distinct in species from that which 

 it was desu-ed to protect. In the case of cattle the virus taken 

 from BUcachas seemed to protect in all cases, whether the illness 

 produced by the inoculation was mild or severe. It w as to be 

 hoped that more extended inquiries would confirm the favour- 

 able results obtained by employing the virus from white mice 

 to protect sheep. The speaker stated that he proposed com- 

 municating the results of his observations on this subject to the 

 Royal Society at an early date. 



SUGGESTIONS FOR FACILITATING THE USE 



OF A DELICA TE BALANCE 

 TN some experiments with which I have lately been occupied, 

 •^ a coil of insulated wire, traversed by an electric current, was 

 suspended in the balance, and it was a matter of necessity to be 

 able quickly to check the oscillations of the beam, so as to 

 bring the coil into a standard position corresponding to the zero 

 of the pointer. A very simple addition to the apparatus allowed 

 this to be done. The current from a Leclanche cell is led into 

 an auxiliary coil of wire coaxial with the oiher, and is controlled 

 by a key. When the contact is made, a vertical force acts upon 

 the suspended coil, but ceases as soon as the contact is broken. 

 After a little practice, the beam may be brought to rest at zero 

 at the first or second application of the retarding force. 



This control over the oscillations has been found so conve- 

 nient that I have applied a similar contrivance in the case of 

 ordinary weighings, and my object in the pre-ent note is to induce 

 chemists and others experienced in such operation ^ to give it a 

 trial. Two magnets of steel wire, three or four inches long, are 

 attached vertically to the scale pans, and underneath one of 

 them is fixed a coil of insulated wire of perhaps fifty or one 

 hundred turns, and of four or five inches in diameter. The best 

 place for the coil is immediately underneath the bottom of the 

 balance case. It is then pretty near the lower pole of the mag- 

 net, and is yet out of the way. The circuit is completed through 

 a Leclanche cell and a common spring contact key, placed in any 

 convenient position. The only precaution required is not to 

 bring other magnets into the neighbourhood of the balance, or, 

 at any rate, not to move them during a set of weighings. 



The other point as to which I wish to make a suggestion re- 

 lates to the time of vibration of the beam. I think that with the 

 view of obtaining a high degree of sensitiveness the vibrations 

 are often made too slow. Now the limit of accuracy depends 

 more upon the smallness of the force which can be relied upon 

 • Paper read at the British Association by Lord Rayleiah, F.R.S. 



