86 J. B. CLELAND. 
What support is there to such a view? To my mind a 
thoroughly rational argument, with important data to sup- 
port it, can be brought forward. I know of no definite facts 
and no reasonable hypothesis to render it unlikely. And 
beyond these I may say that, considering the biological pos- 
sibilities, a cancer is, after all, only what might be expected 
to happen under certain circumstances. 
To explain this view, it 1s necessary to consider the be- 
ginning of the life of a multicellular organism such as man. 
The fertilised ovum, the union of the male and female 
gametes, 1s a pluripotential cell. Its descendants comprise 
all the cells of the body, whether somatic cells or germinal 
cells. As evidenced by experiments in various animals, of 
its early progeny some are likewise pluripotential, inasmuch 
as separation into two component parts may lead to the 
development of two individuals from one fertilised ovum. 
In man homologous twins, who are practically identical in 
appearance and characteristics—were in fact once identical 
—are examples of two individuals thus developed. Some- 
times we see a most remarkable further stage in which. 
after two individuals have started to form from one ovum, 
they have amalgamated again, the right of one twin and the 
left of the other being almost entirely suppressed. One 
individual is formed, but the suppressed limbs of the other 
halves may be recognised in abortive excrescences. 
For how long does this pluripotentiality continue? 
Authorities differ, but many biologists consider that at a | 
very early stage the forerunners of the sex cells are set 
aside for their specific purpose. Some, in fact, consider 
that this germ-plasm is directly continuous from individual 
to individual, and that it is, so to speak, the immortal 
element in us, our bodies as we see them being merely 
temporary tabernacles erected round the germ-plasm to 
protect and nourish it. With the transmission of the 
