Dis-eases are also considered to be acute or chronic. A dis-ease is in the acute stage when there is a “hot box” found at the causative subluxation. When adaptation has taken place and the “hot box” has disappeared, the condition is in the stage of chronicity. Taut fibers will then be present and by their presence the palpation and location of the major subluxation may be verified. It is well for the student to understand what is meant by such expressions as the stage of exposure, the period of infection, the stage of incubation, the period of invasion, the degree of infection, even though we have no particular reason to use such terms in our chiropractic explanations of dis-ease. Stage of Exposure The time during which the person is exposed to the morbific agents is known as the stage of exposure. Period of Infection The period of infection is the time during which the pathogenic germs actually enter the body. Stage of Incubation The stage of incubation is the time during which the morbific agents develop within the body and for the time being have overcome the natural resistance. The incubation period varies greatly in different so-called contagious dis-eases, it being governed largely by the character of the invading germs and the general health of the patient. Period of Invasion The time during which the germs remain in the body is called the period of invasion. Degree of Infection The vital resistance of the body, the portal of entry and the character of the invading germs determines the degree of infection. We wish again to call the student’s attention to the fact that these expressions are not used chiropractically to explain the cause of dis-ease nor the different stages through which dis-ease passes. Contagious A contagious dis-ease is one that is thought to be transferred from one individual to another by personal contact. From the etymology of the term (contingere, to touch) we would conclude that only such dis-eases as syphilis would come under this category. But as the term is generally understood it includes such dis-eases as smallpox, measles and chickenpox. Infectious An infectious dis-ease is one that is supposed to be conveyed from one individual to another indirectly through some medium. Typhoid fever has been given as an infectious dis-ease. Today it is generally considered that the terms, contagious and infectious, do not have a precise meaning which will scientifically differentiate them, for most of the so-called communicable dis-eases may be conveyed in many different ways. The so-called infectious dis-eases may be contagious and the so-called contagious dis-eases are infectious; so we see the terms lack scientific precision and this has led to confusion many times. Morbific Agents