344 
PHYSIOLOGY. 
BOOK II. 
the ovary, which then begins to become excavated at the base; 
and after some time an ovule makes its appearance, having its 
apex directed towards the sphacelated line, and placed in con- 
tact with it. Mr. Griffith does not say that this sphacelated 
line is the course of the pollen tubes, nor that it causes the pro- 
duction of the embryo, as in the last case: but, as eventually 
an embryo is formed in the ovule at the end of a cellular 
suspensor communicating with the sphacelated line, it may be 
reasonably supposed that such is the fact. Mr. Griffith states 
that, in these two cases, the nucleus of the ovule was originally 
solid, and that the embryo is subsequently produced in it by 
an excavating process. 
By some it has been thought that the molecular locomotive 
matter found in the interior of pollen grains represented the 
germs of future embryos, and that the introduction of one 
such molecule into an ovule was necessary in order to insure 
the production of an embryo. But it has been shown that 
the molecules are starch : upon this matter Schleiden has the 
following remarks : — 
“ It appears to me, as if the very minute chemical and 
microscopical researches of Fritsche on the pollen (Peters- 
burg, 1837) have made an end of the so called pollen ani- 
malcules ; for it would be contrary to the laws of animal 
nature, that the lively motions of these apparent infusoria 
should continue undisturbed after the addition of alcoholic so- 
lution of iodine (a poison that immediately kills all infusoria 
and animal spermatozoa), as Fritsche states to be the case, 
and which in many instances I have observed. 
‘‘ In the CEnotheras, however, to which Meyen has particu- 
larly referred, I have not been able to see any thing of pollen 
animalcules (saamenthierchens) ; and in these cases the contents 
of the pollen, quoad solida, also for the greatest part consists of 
starch. I have, at least, in QEn. Simsiana, grandiflora, and 
crassipes, throughout, found nothing else in the pollen be- 
sides a solution of gum and those easily recognisable small 
crescent- formed bodies, which Brongniart has described as 
pollen animalcules. These are, however, decidedly starch, 
and continue starch even when the pollen tube is already 
deep in the nucleus of the ovule. In order, however, in this 
