1882.] 



MICROSCOPICAL JOURNAL. 



123 



ease which he calls pneumo-enteritis 

 of swine, and which is so well-known 

 in this country as hog cholera; but 

 my own investigations do not confirm 

 this, for I have always obtained by 

 cultivation an entirely different or- 

 ganism, being the one which Klein 

 himself discovered in the tissues of 

 affected animals, and which he was 

 led to discard by what I am forced to 

 consider most imperfect cultivation 

 experiments. Even Doctors Wood 

 and Formad are constrained to admit 

 that in their cultivation of the sup- 

 posed virus of diptheria, if the tem- 

 perature was varied, a different or- 

 ganism frequently appeared.* These 

 gentlemen selected the cultivation- 

 apparatus which misled Klein, and 

 which, to say the least, is hardly suited 

 to investigations of this delicate na- 

 ture. 



The writer has used an apparatus 

 of his own, which Avill be fully de- 

 scribed in his report to the Depart- 

 ment of Agriculture of 1881, and 

 which in his hands has given the most 

 complete satisfaction. Instead of 

 using one or two drops of liquid for 

 a cultivation-medium, the usual quan- 

 tity is half an ounce; and this has 

 been increased for special purposes 

 to a quart. A small fraction of a 

 drop of virulent blood added to such 

 an apparatus, with suitable precau- 

 tions for excluding atmospheric bac- 

 teria, will cause the limpid liquid 

 which it contains to become opale- 

 scent, or turbid, within twenty-four 

 hours, and a microscopic examination 

 shows this turbidity to be due to vast 

 numbers of the dumb-bell forms al- 

 ready mentioned. If the blood is 

 obtained and introduced with proper 

 care, it will be in vain for us to search 

 our preparations for other forms of 

 bacteria, and no matter how long we 

 preserve our cultivations, nor at what 

 temperature we keep them, the result 

 will be the same. Having made a 

 pure cultivation of the organism, if 



*Drs. H. C. Wood and H. F. Formad. 

 Report on Diphtheria. — Supplement A'o ly, 

 National Board of Ilea If /i Bulletin, p. 6. 



our apparatus is perfect, it will re- 

 main pure indefinitely. 



With a single cultivation and with- 

 out other tests, we might be uncertain 

 as to whether the bacterium obtained 

 really existed in the blood, or whether 

 it was of atmospheric origin; but 

 when we have repeated the experiment 

 a considerable number of times, al- 

 ways obtaining organisms morphologi- 

 cally the same, and these very different 

 in essential characteristics from the 

 bacteria which multiply in similar 

 liquids after exposure to the air, we are 

 warranted in concluding that they 

 were not introduced from the air but 

 from the blood. 



Now, when we have proved that a 

 certain bacterium exists during life in 

 the blood of affected birds, is that 

 good evidence that the disease is 

 caused by such organisms ? Evi- 

 dently, it is very insufficient, but for- 

 tunately we are able to satisfy the 

 most fastidious on this point, by ad- 

 ditional facts. 



2. Liquids in ivhich bacteria are cul- 

 tivated produce the disease by inocula- 

 tion. — If we add one-fourth of a drop 

 of virulent blood to five hundred 

 drops of cultivation-liquid, and place 

 this in an incubator at 90*^ F. for 

 twenty-four hours, or until the de- 

 velopment of micrococci has pro- 

 duced turbidity, we find that inocula- 

 tion with this liquid as surely pro- 

 duces the disease, and that this is as 

 fatal, as when virulent blood is the 

 material used. But there is a point 

 here that is nearly always overlooked 

 by those who make this class of inves- 

 tigations : -perhaps this cultivation, 

 as we call it, is only a dilution of the 

 original virus — a dilution not suffi- 

 cient to destroy its activity. We have 

 used a half-ounce or more of liquid, 

 and have made a dilution of i to 

 2000 — a dilution much greater, it is 

 true, than is usually made by those 

 who cultivate in but a drop or two of 

 fluid in a small cell — but it is our ob- 

 ject to give a scientific demonstration 

 and not to follow in the uncertain 

 footsteps of those who have preceded 



