68 F. B. BANG 



down during the secretion of milk offers a mechanism of virus release which 

 might occur in infection with the mammary tumor agent so that no patho- 

 logical changes in the cell would be necessary for even a massive release of the 

 virus. The continuous formation and excretion of fairly large droplets of 

 mucus again offers ready exit for virus. Actual visualization of such processes 

 may be difficult. The collection of a variety of special secretory droplets in 

 the cytoplasm offers a particular challenge to anyone trying to identify 

 viruses. Many of these occur in clumps (Bargmann and Knoop, 1957) and 

 may even have dense centers within the individual particle (DeRobertis and 

 das Ferreira, 1957). There is no single method whereby such particles may 

 be differentiated from viruses. 



The extensive knowledge of the sequence of changes occurring in mitosis 

 has been of little use in cell pathology in relation to viruses because of almost 

 complete lack of knowledge of changes produced by virus infections. This, in 

 turn, is due to the fact that most of the virus infections studied have killed 

 the cell before mitosis took place. Probably virus tumor cells would show 

 interesting changes. 



E. Osmotic Changes 



The demonstration with the electron microscope of a detailed lamellar 

 system within all kinds of cells raises interesting questions concerning fluid 

 localization. A recent study of kidney function (Rollhauser and Vogell, 1957), 

 in which the tubular cells during secretion show great accumulation of fluid 

 within these spaces, has particular interest in relation to the pathological 

 accumulation of fluid (see Section III). 



III. Pathological Aspects of Cell Morphology 



General knowledge of the morphological changes occurring in sick cells is 

 an assumed prerequisite for the interpretation of the changes brought about 

 by viruses. Furthermore, one expects some structural change, however small, 

 to accompany biochemical change. Yet, a large proportion of the studies in 

 nonviral cell pathology have come about as by-products of tissue culture 

 observations (Fischer, 1946), or as controls of one sort or another for virus 

 infections (Blackmail, 1936). There are a number of studies on the effects of 

 various mechanical traumas on larger cells (Cameron, 1952), but since most 

 of these deal with marine invertebrate or plant cells, the direct applicability 

 of them to our problem is not clear. For these reasons, we are unable to sum- 

 marize in any logical fashion the progression of changes which occur between 

 early derangement and final death, but we will attempt to classify the types 

 of change found and discuss them briefly. 



