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THE FARMER'S MAGAZINE. 



rot, not only giving his own experience upou the matter, but 

 culling from nearly all those who have written at all 

 sensibly of this affectioa. He comes to the couclusioa that the 

 disease is due to the inhalation of miasm, and heuce that it 

 shows itself more particularly in the summer months, though 

 the progress of the disease carries it over into the autumn, 

 through the winter, and even into the next year. He says that 

 there are many deleterious eniauations coming from the earth, 

 where it is surcharged with moisture in damp and swampy 

 districts; that the sheep inhale this miasmatic matter; that it 

 isduees a bad habit of body, and lies at the foundation of the 

 malady. It is, however, not a little singular that Mr. Yoaatt, 

 in stating facts with reference to the disease, should state one 

 which positively contradicts this theory with regard to miasm, 

 and he appears to have done it without noticing it at the time. 

 The fact to which I allude is this — that on a particular farm 

 there was one field in which there was a swamp, hardly to be 

 called a pond, and when the sheep were turned into the field 

 during the summer months they became affected with rot. 

 This became so obvious to the farmer that after a time he 

 hedged in the pond, and prevented the sheep from having 

 access to the swampy part, and then the disease ceased upon 

 the farm. Now, this being a fact of which I have very little 

 doubt, it at once negatives the idea propounded with regard 

 to miasm. If the pond had been thoroughly drained, the 

 water being entirely removed, and the character of the soil 

 improved, I can understand that miasmatic vapours would 

 not have arisen from it ; but the pond remaining as a poud or 

 swamp, we can of course see that the miasmatic matter would 

 arise from it just as much when it was inclosed with an or- 

 dinary fence as when it was open ; and this therefore strikes 

 at the root, or negatives to a considerable extent, if not en- 

 tirely, the view which Mr. Youatt has taken of this affection. 

 Then we have had other individuals who have spoken of im- 

 pure food as the cause. They say that where there is abund- 

 ance of moisture, together with an elevated temperature, we 

 have a great growth of grass, especially iu damp situations ; 

 that such grass is deficient in nutriment to the sheep ; that 

 the blood produced from such food is impure; and that hence 

 arises a cachectic condition of the body. But this can hardly 

 be said to be the origin of the disiease, since it would be per- 

 fectly impossible for impure food or water, or anything else, 

 simply as impure material entering into the organism, to call 

 into existence these catozoa, upon which the disease depends. 

 Others, again, have looked to certain plants as the cause of 

 the malady ; and there is nothing new in this. I have here a 

 work written by Mr. Maacall, who was I believe the chief 

 farrier to King James. It bears the date of 1587, and is the 

 original edition. It treats of the maladies of cattle, and it 

 has this passage : " It is good for al men to understand, spe- 

 cially shepheards, which things do hurt or rotte sheepe, 

 whereby, they male avoide the danger the better, ye shal 

 understand there is a Grasse or weed called Speare Wort, 

 the leaves are loug and narrow like a speare, hard and 

 thick, the steaks hollow, growing a foote or more high, 

 with a yellow floure, which is comonly in wet places, 

 and there wil it grow most, or where water have stood in 

 the winter. There is also another weed called Peniwort 

 or Penie-grass ; it wil corconly grow iu moist and msrrish 

 grounds, and it groweth low by the ground, and 

 hath a leafe on both sides of the stalke like unto a penie, thick 

 and round, and without floure, yet some doe saie it beareth a 

 yealow floure, which will (as they say) kil sheepe if they eat 

 it. Alsoe all manner of Grasse that landfloods doe overrun 

 before a raine is not good for sheepe." Coming down to later 

 times, we have had a theory which certainly ought not to be 

 rejected without due consideration. It is founded entirely 

 upon the existence of the fact that in this disease we have 

 certain entozoB, to which I shall allude more fully, that are 

 inhabiting the biliary ducts of the liver. These entozoa pro- 

 duce a number of eggs ; these eggs pass out of the liver into 

 the intestines, and are consequently expelled with the feculent 

 matter of the sheep, in countless myriads it may be said. 

 Some time ago a Mr. King (I do not know whether he had a 

 medical education) wrote a series of papers in the Bath 

 Society's Journal, in which he propounded the theory that 

 the rot in sheep was due to this circumstance : that healthy 

 sheep, if put upon pasture grounds where these eggs exist 

 upou the soil, receive them into their organisms ; that the 

 egg produces the fluke, and that the fluke would consequently 



thus find its proper liaUlal — it would f eek cut matinctivtly 

 the biliary ducts of the liver, wliere it would locate itself and 

 grow to perfection. This theory of the simple introduction 

 of fluke eggs certainly did seem to have common sense for 

 its foundation ; but it was found, after a certain length of 

 time, that there was little or no truth even in it; that the ova, 

 for instance, of the fluke did not immediately produce young 

 flukes. Some 10 years ago I put this to the test of positive ex- 

 periment. I collected a great number of the eggs of the fluke 

 — far more than it would be possible for a aheep to receive into 

 its stomach in the course even of a summer's grazing. I took 

 no less than a tea-apoonful of them, and it would be scarcely 

 possible for you to count the number in a single drop of the 

 water ia which they are placed under the field of a micro- 

 scope; and these, to the number of millions, I conveyed into 

 the system of a sheep, which I kept six mouths, and then 

 had it destroyed. Ou examining its liver and other organs I 

 found that there were no entozoa at all in the biliary ducts. 

 In reality there was not a single fluke produced from those 

 millions of eggs so carried into the system of the sheep. This 

 negative result was exceedingly valuable, and I may further 

 remark that it fully confirms similar experiments carried out iu 

 Germany. Gerlach, who is connected with the Berlin school, I 

 believe, has had recourse to experiments Of the same kiud, and 

 invariably with the eame result, thus proving that the ova of the 

 fluke, if carried into the system of the sheep will not generate 

 or develope themselves into flukes. We find then, that all these 

 theories have been more or less at fault, and it is only within, 

 comparatively speaking, a very short; space of time, that we 

 have approximated to anything like one which will explain the 

 pathology of the disease. You will remember that I stated I 

 was anxious to confine my remarks entirely to the malady in 

 which we have certain entozoa within the biliary ducts. In the 

 diagram before you you have a representation of one of these 

 creatures. It is called the Distoma hepaticum, and is so desig- 

 nated in consequence of its having apparently two mouths or 

 sucking discs — one placed at the anterior part of the body, 

 which may be truly regarded as a mouth; and the other placed 

 on the ventral surface, at a short distance below the neck, just 

 where it terminates in the bod}'. The animal, as I have said, 

 inhabits the biliary ducts of the liver (which you have repre- 

 sented in this diagram) ; and if we slit up these ducts in any 

 case of this kind we shall find that they are filled more or less 

 to repletion with these distoma. Before going into the natural 

 history of these creatures I may say that after a certain length 

 of time they lead to au auiemiiiated condition of the entire 

 organism. They not only feed upon the bile which is pro- 

 duced, but they alter the structure of the liver by their pre- 

 sence, just as we find with entozoa in other parts, and when 

 this is the case it is of csurse perfectly impossible for the liver 

 to secrete healthy bile, any more than pure water can flow 

 from an impure spring. The bile plays an important part in 

 the manufacture of blood, and if it is not in a healthy condi- 

 tion, pure blood canuot be produced from the food which the 

 animal takes. The result is that the entire orgauism is sup- 

 pUed with impure blood, while the system is being draiued by 

 the presence of these creatures. After a certain length of 

 time we find that dropsical effusions take place, and 

 then we have the disease established iu all its in- 

 tensity and in all its destructivencss. Having thus shown 

 you that this is truly to be considered as au entozoic disease, 

 it becomes a matter of great importance to see how these 

 entozoa really do inhabit that part of the system of the 

 sheep. When speaking of sheep, however, I may be allowed 

 to remark, that although the affection is moat destructive to 

 this animal, it is not exclusively a sheep-disease. These 

 creatures have been found not only in cattle, but in pig?, in 

 the ass, and also in the human subject. They are very widely 

 dispersed, but it i« in the sheep in particular that they accumu- 

 late in such numbers as absolutely to produce this special or 

 specific malady. We come now to inquire a little into 

 the natural history of the distoma, that we may see what 

 light it will throw on the nature and progress of the disease, 

 and upon the means at our disposal for preventing or curing 

 the affection. It ia self-evident that if a disease depends upon 

 a special entozoon, if we are thoroughly acquainted with the 

 natural history of the creature, and if by means of that know- 

 ledge we can destroy it or get rid of it, we shall thus be able 

 to neutralize its effects ; for if we remove the cause, the effects 

 must cease. Now, without unnecessarily occupying time, 



