CHAPTER III 

 IMPERFECT VIRUSES 



1. Eczema or Allergic Dermatitis 



There is a large group of skin diseases called eczema, a dermatitis 

 usually accompanying itching, erythema, vesicles or pustules. It is 

 acknowledged that for the occurrence of this disease both the predis- 

 position liable to be affected by this disease and adequate external 

 irritants are needed. 



The mechanism of eczema formation may be as follows : Skin 

 cells having the predisposition may change in their protoplasm struc- 

 ture by the effect of a stimulus, and the change thus occurs may 

 subsequently spread successively to surrounding cells followed by 

 various pathological symptoms. The symptoms may be attributed in 

 the main to the disturbance in autonomous nervous systems. 



An abnormal reactivity of man to some agents is termed allergy, 

 and eczema is commonly regarded as a kind of allergy. It should be 

 borne in mind that allergy cannot exist without a peculiar predisposi- 

 tion which is occasionally hereditary and that the symptoms cannot be 

 brought about without a proper stimulus. Common cold, as mentioned 

 in the previous chapter, is also raised when a stimulus, chilling, acts 

 upon the peculiar predisposition, although some other factor or factors 

 appear to be needed, and hence sometimes common cold is also re- 

 garded as a kind of allergy. 



If, in the case of allergic dermatitis, the fragments or particles of 

 changed protoplasm were stable enough to retain its changed struc- 

 ture, they would be able to give rise to the same changed structure 

 in other healthy cells as a virus. This is, however, never the case, 

 presumably because of the lability or the weakness of the newly in- 

 duced structure. The dermatitis cannot be called, therefore, a virus 

 disease, although it may not be quite impossible to transmit the dis- 

 ease through the protoplasm fragment, if the latter is applied to a 

 proper healthy region of the skin of the same individual immediately 

 after the isolation. 



The newly induced structure causing the dermatitis seems to be, 

 on the one hand, stronger than the original, because the structure 

 has to overcome the original structure at least for the period of its 

 spreading, while on the other hand its strength seems to be lost 



