REPRODUCTION OF BACTERIA AND VIRUSES I37 



multiplication of genetically active units in bacteria in- 

 volve all the steps concerned in mitosis, particularly 

 when these events are viev^ed from the morphological 

 level. When we turn to the multiplication of bacterio- 

 phages and viruses it is possible that we are dealing with 

 a different or at all events much simplified process, with 

 which the possible routes of interference are more re- 

 stricted. It is quite likely that the reason why the common 

 bacteriostatic agents and mitotic poisons seem to be of 

 little use in the treatment of virus diseases is that some 

 of the specialised processes involved in mitosis simply 

 do not occur in the reproduction of viruses, and that it is 

 these rather specialised processes which are primarily 

 attacked by the known poisons. 



If it is indeed the case that virus reproduction is a 

 simpler process than mitosis, it may be necessary to look 

 for rather different physico-chemical phenomena as pos- 

 sible modes of attack in the designing of substances which 

 will prevent the production of viruses. For example, the 

 study of viruses in vitro may well lead to the discovery of 

 types of substances which are selectively adsorbed upon 

 them: such substances may well prevent the reproduc- 

 tion of viruses. Then certain viruses have been shown to 

 attach themselves to particular points on the surfaces of 

 cells, and it has also been shown that particular sub- 

 stances may be necessary to secure this attachment. 

 From this, two possibilities arise for the design of com- 

 petitive substances: one type of substance which would 



