70 CHRISTIANNA SMITH 
was undertaken at the suggestion of Dr. B. F. Kingsbury, whose 
kindly interest and generous help is gratefully acknowledged. 
The conclusions reached were that lipoids could be demonstrated 
in kidney cells by special technique, that the distribution and 
formations of the lipoids were more characteristic in some species 
than in others, and that some lipoids may be intracellular in 
origin. 
Although it is agreed that lipoid is a poor term, chemically 
speaking (Leathes, 710), ‘‘it is useful in histology to include fats, 
fatty acids, phosphatids, cholesterol, etc., substances which 
have the same solvents and which are found associated in cyto- 
plasm,” (Kingsbury 715), and as such it will be employed in 
this paper. 
If these lipoids are universally present in cells, as it is believed 
they are by chemists and histologists (Fischer and Hooker, 717; 
Kingsbury, 715), the question arises as to the forms in which 
they exist and their relation to the other cell contents in the cell. 
Fischer and Hooker believe that in normal cells and fluids, liquids 
(Fischer and Hooker use the term ‘fat’) are present in finely 
divided form, kept so by various hydrated proteins, and that the 
amount of lipoid varies greatly not only in a given cell or 
body fluid under different physiological and pathological circum- 
stances, but also at all times, in different cells and fluids. It is 
because of these fine emulsions, they say, that large amounts of 
lipoids may be present in certain tissues and not betray them- 
selves optically or by ordinary fat stains. According to this 
interpretation, fatty degeneration is merely a coarsening of the 
normally fine emulsions due to the separation of the lpoids 
because of an interference with the hydration of the proteins. 
This interference is, according to them, acid production, caused 
by substances such as phosphorus, phlorizin, alcohol, and con- 
ditions of anaemia or general circulatory disturbances. 
That some of the lipoids in cells are present in intimate mixtures 
has already been pointed out (Kingsbury, 711), and that one 
of these mixtures is represented by mitochondria seems at present 
unquestioned. Cowdry (’16) in the paper to which reference has 
already been made, gives the following summary of the chemistry 
