PRESIDENTIAL ADDRESS. 87 
sacred germ-plasm to the custody of a new generation, this 
domicile returns to dust and ashes again. Whilst admit- 
ting the relatively early differentiation of the germ-cells in 
the higher animals, I do not agree with the view that the 
gverm-plasm is set aside so early that it is correct to say 
that there is direct continuity of it from generation to 
generation. An analogy with the protozoa will make my 
meaning clear. The malarial organism, introduced into 
man, multiplies. Brood after brood of asexual forms are 
developed, giving rise during their evolution to the symp- 
toms and signs of the disease. These asexual forms are the 
representatives of the somatic cells of the body. If, instead 
of being separate units, like the cells in our blood, they 
were all brought together and made dependent one on the 
other, we would have a soma. LEventually, arising from 
these forms after various generations, gametes appear. 
These are the sex cells, incapable apparently of further 
development in the vertebrate host, incapable of causing in 
such the signs of disease, capable only of multiplying again 
after sexual conjugation in the mosquito. If, in the so- 
ealled lowly protozoon, we have a long series of X 
somatie generations, on which eventually are superadded 
Y gametogenic generations leading to the evolution of the 
gametes, why should we not have in man, for instance, a 
similar series of X somatic generations, followed by Y 
gametogenic generations, amongst that group of cells set 
aside for the purpose of reproduction? In my opinion, such 
a series of somatic generations does precede the gametogenic 
ones, and these somatic generations are no more a direct 
continuance of the germ-plasm than are the somatic 
generations of other tissues of the body. I  fur- 
ther believe that in these other cells, that is those 
not originally set aside for reproductive purposes, 
the capacity to form gametoid tissue is latent, and not ab- 
sent or eliminated. Under ordinary circumstances, such 
