346 
PHYSIOLOGY. 
BOOK II. 
three circumstances speak for the identity of the embryo with 
the pollen tube. 1. The constantly equal diameter of the 
latter, exterior to the embryo-sac, and of the former, just 
within it. 2. The invariable chemical similarity of their 
contents, shown by the reaction produced by the application 
of water, oil of sweet almonds, iodine, sulphuric acid, and 
alkalies. The general contents of the grain of pollen is starch ; 
and this either proceeds unchanged downwards through the 
pollen tube, or else passes along, after being changed by a 
chemico-vital process into a transparent and colourless fluid, 
which becomes gradually more and more opake, and is 
coagulable by the application of alcohol : out of this, by an 
organising process, the cells are produced which fill the end 
of the pollen tube, extending, in Orchis Morio, far beyond 
the ovule, and thus forming the parenchyma of the embryo. 
3. The identity of the embryo and the pollen tube is 
farther supported by the fact, that, in such plants as bear 
several embryoes, there is always precisely the same number 
of pollen tubes present as we find embryoes developed. 
“ The most important result of these facts is, that the sexual 
classification hitherto adopted in botany is directly false : for, 
if the ovulum be understood in physiology to represent that 
material foundation from which the new being becomes 
immediately developed, and if we term that portion of the 
organism in which this material commencement is deposited 
before it becomes developed the female organ, whilst that part 
which calls into action or promotes the developement of the 
germ by means of its potential effects is termed the male 
organ, it is evident that the anther of the plant is nothing but 
a female ovarium, and each grain of pollen the germ of anew 
individual. On the other hand, the embryo- sac only works 
potentially, determining the organisation and developement of 
the material foundation ; and for this reason, therefore, ought 
to be termed a male principle, were we not to consider, perhaps 
more correctly (without embarrassing ourselves with lame 
analogies taken from the animal kingdom), that the embryo- 
sac merely conveys new organisable fluids by means of 
transudation, and thus only serves the office of nourishment. 
“ In the next place, the process of developement of the 
