1 B 2 
W. Neilson Jones. 
After a time however the balance between the two cell components 
ceases to be so well adjusted and one begins to gain an ascendancy 
either through its quantitative increase or because it has become 
more virulent in quality (cf. the way in which the balance of the 
ordinary symbiotic organisms can be disturbed by one partner 
becoming more virulent under certain conditions of culture). 
Thus the protoplasm becomes more andropiasmic (“ active”) or 
gynoplasmic (“ passive”) in quality and the cells reach a condition 
in which they are ready to fuse again, that is to say the pro¬ 
toplasm of the two cells becomes sufficiently unlike for them to 
function as gametes. The rapidity with which the andropiasmic 
and gynoplasmic types of protoplasm become thus differentiated 
or segregated will depend doubtless in some degree on the 
environmental conditions, supply of nutriment, etc. In multicel¬ 
lular plants, special conditions of nutriment, etc., occur in different 
regions, so that one would expect that certain regions of the 
plant organism would show a special tendency towards the 
differentiation into the two kinds of protoplasm, i.e., towards 
the formation of gametes of one kind or the other. 1 
In the higher plants, for example, the conditions occurring in 
the anthers or microspores appear to favour specially the 
development of the andropiasmic type of protoplasm, while the 
conditions in the embryosac tilt the balance in the opposite 
direction and favour the differentiation of gynoplasmic proto¬ 
plasm. Whatever the actual causes may be, similar forces are 
probably ultimately responsible both for the differentiation of the 
gametes from the general body of the multicellular plant and for 
the differentiation and determination of the gender of the gametes 
that occurs in a single species of Chlamydomonas, such as 
C. Braunii. 
In the case of a flowering plant the complete cycle will be 
as follows. The andropiasmic and gynoplasmic gametes, uniting 
at fertilisation, establish in the zygote the symbiotic partnership of 
“active” and “passive” varieties of protoplasm. This part¬ 
nership persists throughout the development of the zygote 
(sporophyte), including the formation of the flowers with their 
anthers and ovaries. The segregation into androplasm and 
gynoplasm does not occur, probably, until (or shortly before) the 
1 Compare Vaucheria, etc., in which, as shown by Klebs, the occurrence 
or inhibition of reproduction and the nature of the reproductive cells is 
directly correlated with external conditions. 
