102 II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



We were able to demonstrate that phage and vaccinia virus are 

 most stable in water containing no salt ; under such a condition their 

 folding is considered to be most complete (133) (134). Inorganic salts 

 except those of divalent cations, such as calcium and magnesium, al- 

 ways render the phage more susceptible to heat. As was already dis- 

 cussed, divalent cations can cause virus particles to become rigid and 

 stable, whereas salts of monovalent cations may cause their unfolding. 



The disappearance of virus in host cells on the infection has been 

 confirmed also with influenza virus. According to Isaacs and Edney 

 (135), influenza virus injected into allantoic sac is mostly adsorbed by 

 the chorio-allantoic membrane, but only less than 1 per cent of the in- 

 oculum is recovered from ground supsensions, recovering of the virus 

 being reduced further by 10 fold, if membranes are incubated before 

 grinding. Such a difficulty of recovering may naturally result, when 

 the virus undergoes a change into an unstable stretched form on the 

 surface of host cells so as to be inactivated during the isolating ma- 

 nipulation. According to Rountree (136) phage particles adsorbed onto 

 host cells lose first its infectivity, followed by its antigenicity, and then 

 ensues a period, from 12 to 19 minutes after the infection, during which 

 neither infective phage nor antigen can be recovered from cells. 



There are, however, evidences suggesting that viruses are destroyed 

 on the infection in situ not during the isolating procedure. For in- 

 stance, in biochemical studies of phage reproduction, Kozloff (137) 

 claimed that all phage particles are partially broken down upon adsorp- 

 tion on the host cells ; up to 80 per cent of the desoxyribonucleic acid 

 and protein nitrogen of the adsorbed virus are decomposed during virus 

 reproduction to a various small fragments. 



This suggests that the adsorbed virus particles because of their un- 

 stable, stretched form may be influenced considerably by the assimilase 

 action of the host cell protoplasm so as to be decomposed, although 

 some of them may be able in the long run assimilize the protoplasm. 

 In the writer's concept, as will be detailed in Part IV, Chapter V, when 

 two protein molecules having different structures are held together, 

 they exert to one another physicochemical influences due -to the differ- 

 ent structure, and when the effect of the one is stronger enough to 

 decompose the other, the former is called the proteolytic enzyme of 

 the latter. In this respect, the host protoplasm may be said to act as 

 an enzyme upon some of the adsorbed virus. Jesaitis and Goebel (138) 

 have isolated water soluble, somatic antigen from a strain of dysenteria 

 bacillus. This substance was found to inactivate all phages to which 

 the bacillus is susceptible, and they (139) held the opinion that this 

 substance serves as the receptor for phages which attack this bacillus. 

 According to the theory of the writer, such a somatic antigen is noth- 



