392 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



winter, particularly in the latter part of December (1878) and in tlie 

 month of January (1879), the temi)erature of the atmosphere was very 

 low ; it snowed considerably ; the snow became very deep and covered 

 the ground for a long time ; consequently, everj'thing on the surface of 

 the ground remained unchanged and unmoved, and the evaporation of 

 moisture was A^'ery limited. The disease-producing- germs, or the Schiz- 

 omycetes, which constitute the cause and infectious principle of s\^^ne 

 plague, although not immediately and necessarily destroyed by frost 

 and snow — recent developments have shown that these germs may re- 

 tain their vitality for a considerable length of time even if imbedded in 

 ice — were prevented from rising into the air, and thus from being carried 

 by winds from one place to another, neither could the same be conveyed 

 from one herd to another in streamlets and currents of water, because 

 everything- was frozen and covered with snow; consequently, these 

 germs or Schizomycetes could not propagate ; they were kept dormant 

 or in a state of rest, and there can be no doubt that a great many, per- 

 haps most of them, were thus i)revented from finding their proper nidus 

 and therefore perished. Consequently, in the latter part of the winter, 

 1879, but little disease was existing. The plague had almost died out 

 everywhere. Toward spring, however, sporadic cases made their ap- 

 pearance, especially at the borders of timber lands and in swine yards 

 and pastures which contained old straw stacks, or something of a simi- 

 lar nature calculated to give shelter and protection and the means of 

 propagation (warmth and moisture) to the Schizomycetes or disease- 

 producing germs. From such centers, at the close of last winter when 

 snow and frost disappeared, the disease commenced slowly to spread, 

 "but in the spring nearly every week or ten days a pouring rain set in 

 and ijrobably washed away most of the germs or Schizomycetes which 

 existed at places accessible to swine, or at which a chance was given to 

 enter the organism of a hog or ])ig with the food or water for drinking. 

 Be that as it may, one thing is certain, immediately after a heavy or 

 pouring rain a perceptible stop or cessation could be observed in the 

 spreading of the disease, while each time after the lapse of about a week 

 a renewed spreading took place, to be interrupted only by the next heavy 

 or pouring rain. Thus the plague made but little progress until th^e 

 pouring rains became less frequent or ceased altogether, or till July and 

 August, when a drier season set in, in which heavy dews took the place 

 of heavy rains ; but even then, in midsummer, swine plague failed to 

 make as rapid progress as a year ago (1878), because the season very 

 soon became too diy to be favorable to a rapid and extensive propaga- 

 tion and dissemination of the disease-producing elements. Further, 

 during last fall and the larger part of the i^resent winter, the season, 

 with brief interruptions, has been very dry, at any rate in Henderson 

 County; and it seems a dry season is not at all favorable to the propa- 

 gation of swine plague, unless drainage is very poor and the soil is in- 

 clined to be wet. Careful observation has convinced me that continued 

 dry weather on the one hand and pouring rains on the other have a 

 decided tendency to reduce, and a common wet spell, brought about by 

 repeated light rains — a few of about a week's duration were experienced — 

 wUl invariably promote the spreading of the disease. If it is taken into 

 consideration what has been ascertained in regard to the nature of the 

 Schizomycetes, and the manner in which they are conveyed from herd 

 to herd, and from animal to animal {cf. below), no explanation will be 

 necessary. 



Whether the circumstances just related have also diminished the in- 

 tensity of the infectious principle or the vitality of the Schizomycetes 



