12 DISEASES OF SWINE AND OTHER ANIMALS. 



as the blood-corpuscles conuneiice to decompose or i)utrefy. They are 

 also destroyed if brought in contact with or acted ui)on by alcohol, car- 

 bolic acid, thymol, iodine, &c. The destruction of these germs by de- 

 composition -would seem to account for the harmless nature of thoroughly 

 putrid products when consumed by healthy animals. (See drawings, 

 hacilU and hacUlus-germs.) 



Dr. Law also discovered bacteria in the blood of i^igs suffering with 

 the disease, and in one case, on the second day before death, he found the 

 blood swarming with them, all showing very active movements. (See 

 drawings, Plate xiii. Fig. 3.) The blood from another pig, which had 

 been inoculated from this one, showed the same living, actively-moving 

 germs in equal quantity. They were further found in the blood of a 

 rabbit and of a sheep inoculated from the first-mentioned pig. In an 

 abscess of a puppy, which had also been inoculated, the germs were 

 abundant. In the examination of blood from healthy pigs the micro- 

 scope failed to reveal the presence of these organisms. Dr. Law states 

 that in his experiments the greatest precautions were taken to avoid 

 the introduction of extraneous germs. The caustic potash emi^loyed was 

 first fused, then placed with reboiled distilled water in a stoppered bot- 

 tle which had been heated to red heat. The glass slides and cover- 

 glasses were cleaned and biu'ned, the skin of the animal cleaned and 

 incised with a knife that had just been heated in the flame of a lamp. 

 The caustic solution and the distilled water for the immersion-lens were 

 reboiled on each occasion before using, and finally the glass rods em- 

 ployed to lift the latter were superheated before being dipped iii them. 

 On diiferent occasions, when the animal was being killed, the blood 

 from the flowing vessels was received beneath the skin into a capillary 

 tube which had just been purified by burning in the flame of a lamp. 

 With these precautions he thinks it might have been possible for one or 

 two bacteria to get in from the atmosphere, but this would not account 

 for the swarms found as soon as the blood was placed under the micro- 

 scope. 



The most scrupulous care was observed by Dr. Law in his experi- 

 ments in inoculation. The isolated and non-infected locality where the 

 experiments were conducted offered special advantages for a series of 

 experiments of this character, as there were no large herds of diseased 

 and exposed swine, and, consequently, no danger of accidental infection 

 from other sources than the experimental pens. The number of animals 

 subjected to experiment was limited by the necessity for the most per- 

 fect isolation of the healthy and diseased, for the employment of sepa- 

 rate attendants for each, and for the disinfection of instruments used 

 for scientific observations, and of the persons and clothes of those neces- 

 sarily in attendance. Th(i experimental pens were constructed on high 

 ground in an open field, with nothing to impede the free circulation of 

 air. They were large and roomy, with abundant ventilation from back 

 and front, with perfectly close walls, floors, and roofs, and in cases 



