INTRODUCTION 13 
probably plays some part in cell metabolism, may 
furnish material for building up nucleins, and ac- 
cording to Fauré-Frémiet is concerned in the forma- 
tion of mitochondria. Cholesterin is considered a 
waste product of cell life, although it is known to in- 
hibit hemolysis produced by certain bodies and is 
thus a protective against toxins, and may have 
other functions. We should look forward with great 
interest to the results of investigations that are now 
being carried on by biochemists, since we depend 
upon them for an explanation of many of the phe- 
nomena of life, cellular differentiation, and heredity. 
We even hope that they may be able to create 
compounds in the laboratory that we may consider 
living organisms. However, the task does not 
seem to be so simple to the biochemist, who should 
know, as it does to the biologist. Nevertheless, 
as Jacques Loeb has said, we should “‘either succeed 
in producing living matter artificially, or find the 
reasons why this should be impossible.” 
Creuu Division. Cells may increase in number by 
direct (amitotic) or indirect (mitotic or karyokinetic) 
division. There is no doubt that mitosis occurs, 
but not all investigators are convinced that cells 
ever divide amitotically. Direct division was once 
considered the only method of cell multiplication. It 
was described as a simple division of the nucleus 
into two parts (Fig. 2), preceded by a division of the 
nucleolus into two, and succeeded by a constriction 
of the entire cell; the result was two daughter cells 
each with one nucleus containing one-half of the 
