184 W. Neilson Jones. 
tion of a cancer is due to the rejuvenescence of certain cells—these 
cells becoming free from the correlation that normally controls the 
growth of the organism and leading an independent existence as a 
parasite upon the rest of the tissues. Is it possible that this may 
be a manifestation that the balance between the two protoplasmic 
components has been disturbed, that cells of the potentially “active” 
kind have lost correlation with the tissues as a whole and become 
parasitic on the symbiotic organism in the same way that the myco- 
rhizal fungus of a mycorhizal plant may become parasitic upon the 
plant when the resistance of the cells of the latter has been impaired 
or lowered ? The fact that a correlation has been established 
between certain types of cancerous growths and the presence of 
specific poisons or stimulants is in harmony with such a view. 
It is convenient at this point to summarise the proposi¬ 
tions that have been put forward in the course of this article 
These are :— 
1. The phenomena of fertilisation show so many points of 
resemblance with those of parasitism and symbiosis that 
the one is probably only a special case of the other. 
2. Cytological and genetical evidence, as well as mode of 
origin, points to the zygote having a dual structure, which 
has been likened to a symbiotic organism in which the partners 
are androplasm or “ active” protoplasm, andgynoplasm or 
“ passive” protoplasm, derived from the respective gametes. 
3. These two varieties of protoplasm are found more or less 
pure in the gametes, i.e., the mixed protoplasm becomes 
differentiated into its two component parts at or before the 
formation of the gametes. 
4. Two sets of so called “ sex ” determinants must be dis¬ 
tinguished. 
(a.) Sex factors which determine the sex characteristics 
(e.g., type of spore production in the case of vascular 
plants) of the hypothetically symbiotic organism. 
(&.) Those which are responsible for the differences, such as 
relative activity and passivity, shewn between the 
protoplasm of androplasmic and gynoplasmic gametes 
(gender factors). 
The former, (a), obey the ordinary Mendelian scheme of 
inheritance and are carried indifferently by either gamete, 
upon the nature of which they cannot therefore have any 
influence. 
