12 
THE ORGANIC CELL 
term ‘spermatozoa’ by which they are even now generally 
spoken of. 
An Italian naturalist (Spallanzani) showed that the fertilis- 
ing power existed in the spermatozoa, and not in the medium 
in which they move, because, on filtering, the spermatic fluid 
loses its power. 
The next step was the demonstration of the fact that the 
spermatozoa take their origin directly from the cells of the 
testis, that they therefore are not parasitic, but, like the ovum, 
are directly derived from the parent. 
A little later it was shown that the spermatozoon consisted 
not only of a nucleus, but also contained cytoplasm. Its 
purely cellular nature was thus clearly shown, that though 
of extreme minuteness, and possessing a long tail and con- 
siderable motive power, still morphologically it was as true 
a cell as the ovum. Ten years later (1875) Hertwig showed 
that when fertilisation of the egg occurred this phenomenon 
was the result of its union with one spermatozoon, and only 
one. Thus in the process of sexual reproduction each parent 
supplies a single cell of its own body, which on uniting produce 
the offspring — a practical corroboration of the conclusions 
drawn by Galton and Darwin, that the sexes perform equal 
though not identical parts in the process of hereditary trans- 
mission. It is therefore evident that the questions of 
fertilisation and inheritance are cell problems. 
The question now arises : How do the cells of the body 
originate ? As early as 1885 it was known that cells arose 
by the division of pre-existing cells. There were two different 
methods by which cells were supposed to come into existence : 
(1) by division of a pre-existing cell ; and (2) by what was known 
as 4 free cell formation,’ which supposed that cells could 
crystallise out from a nutritive substance called the 4 cyto- 
blastema,’ and, strange to say, this latter method was supposed 
to be the more typical. After some years it was proved that 
4 free cell formation ’ was a fallacy and that such a method 
did not exist in Nature. In 1855 Virchow upheld the universal 
nature of cell division, stating clearly that every cell is the 
result of a pre-existing cell, concluding his statement with 
the now famous biological aphorism 4 omnis cellula e cellula.’ 
