Those who have not been affected can be immunized the same as those who have been bitten. The individual who has been bitten by a mad dog realizes when and how severely he has been bitten, and were it not for the so-called period of latent development of the virus, it would not be possible to carry out the Pasteur treatment. The patient may, if he will, take advantage of this fact and be immunized by treatment before the disease has developed. Deep and severe bites are most dangerous, but the disease may develop simply from a rabid dog licking a scratch of the skin. As before stated bites on exposed or uncovered surfaces, are more dangerous than those through clothing. There is a very easy access of the saliva to the wound in the unprotected part, while in the protected parts the teeth in passing through the protection, clothing, are freed of their saliva at least partially. The virus is conveyed from the bitten part or inoculation to the central nervous system through the nerve trunk, and the rapidity of extension depends upon the resistant powers of the patient, the virulence and the amount of virus deposited in the bitten part at the time the person was bitten. This disease develops only in nerve tissues. Virus can be found in the nerves of the side bitten, while the corresponding nerves on the opposite side are free from it. It can be ascertained that the virus is present in the medulla oblongata before the lower portion of the cord. [248 MOTHERS' REMEDIES] Comparative danger.--A wound of the hand after a delay of three weeks is as dangerous as a bite on the head exposed only a few days. There is always a possibility of an accumulative action and extension of the virus along the nerve trunk to the central nervous system during the interval of exposure, and this should be always borne in mind. It is stated by authority that the virus is not transmitted by the bite of a rabid animal until two days previous to the appearance of the first symptoms. It is with some difficulty that a decision is reached in advising patients who are bitten to take treatment early in the course of the disease. The symptoms are often so very obscure and slight that they are not recognized. If a dog which is not naturally vicious suddenly bites without any cause it should be tied securely and watched for seven days; and should it develop symptoms of the disease during this period the bite should be considered dangerous.