406 



SCIENCE. 



[N. S. Vol. VIII. No. 195. 



lence of winds in the region of the Plains 

 is hostile to agriculture, by reason of the 

 increased transpiration from vegetation 

 and the evaporation from the soil thereby 

 produced ; and trees planted in masses or 

 large groves, in selected locations, form ex- 

 cellent wind-breaks and protect the crops 

 for some distance to leeward of them. The 

 Bulletin contains full descriptions of the 

 various experimental plantings and is well 

 illustrated. 



R. DeC. Ward. 

 Haevaed University. 



BACTERIOLOGICAL NOTES. 

 The bearing of optical aids upon the 

 growth of our knowledge of disease-pro- 

 ducing germs is well illustrated by two 

 contributions recently made to the Ninth 

 International Congress of Hygiene and 

 Demography, held at Madrid. The work of 

 Loeliler and Frosch on bhe {etiology of foot 

 and mouth disease in cattle was reported. 

 The disease-germ of this disease is so small 

 that it passes, contained within the lymph, 

 through Berkefeld filters that hold back 

 the smallest known microorganisms. This 

 germ is thus far known by its effects only, 

 for the highest power of the microscope fails 

 to disclose anything in the filtered lymph, 

 which is yet capable of setting up the dis- 

 ease upon inoculation. That the disease 

 does not depend upon some soluble toxic 

 agent contained within the lymph is proved 

 by the fact that the disease has been trans- 

 mitted through a series of six animals, the 

 original material, which was employed for 

 the first inoculation, having been obtained 

 from a case of the natural disease. In each 

 successive inoculation the Ijmph was fil- 

 tered. We know of no toxic substance so 

 potent, nor, indeed, is it probable that 

 anything but a living and multiplying 

 organism could be so active as to be trans- 

 missible through such a number of cattle, 

 each one of which succumbs in turn to the 



disease produced. These authors do not 

 even conjecture as to the probable character 

 of the microorganism concerned. 



The microorganism of infectious pleuro- 

 pneumonia of cattle has also been sought 

 by many bacteriologists. It has just been 

 obtained by Nocard and E,oux. The lymph 

 taken from the affected lungs is highly in- 

 fectious and readily produces the disease in 

 cattle upon inoculation. Cultures made 

 with this material had always remained 

 sterile, and most painstaking search had 

 failed to reveal any foreign elements in the 

 lymph. By a novel procedure, first intro- 

 duced by Metschnikoff, Nocard and Roux 

 succeeded in obtaining cultures of the mi- 

 croorganism. If small sacs (or bladders) 

 made of celloidin are filled with sterile bouil- 

 lon and placed in the peritoneal cavity of 

 the rabbit they undergo no change, the 

 fluid remains clear and limpid, and the 

 animal is unaffected. If, however, a minute 

 quantity of the lymph from an infected lung 

 is introduced into the sac, after a period 

 the bouillon becomes opalescent. Trans- 

 plantation from one sac to another brings 

 about similar results. Microscopical ex- 

 amination of the turbid fluid shows an en- 

 tire absence of wandering or other body 

 cells, but a magnification of 1,600 to 1,800 

 times brings to light very minute round or 

 elongated bodies which are believed to be 

 the parasites of the disease. After the sacs 

 have remained for a time in the abdominal 

 cavity of the rabbit these animals lose 

 weight and become cachetic. Albumen 

 probably diffuses into the sacs and toxic 

 substances into the peritoneal cavity. These 

 cultures are exceedingly active and produce 

 the typical disease upon inoculation. At 

 first all attempts to cultivate this minute 

 organism outside the body failed, but later 

 through the use of a special culture medium 

 success was achieved. 



It is safe to assume that the parasite of 

 foot and mouth disease is much smaller 



