POLLEN-BODIES OF THE ANGIOSPERMS. 
23 
finds the nuclei of the same form^ and this also when they 
are less developed. 
I have tried to follow the nuclei until the moment of fer- 
tilisation. In Gymnadenia conopsea, used as a favorable 
object of research, I was able to make out definitely that the 
nuclei were to be found som.e distance from the point in those 
tubes which had already pressed their way into the micro- 
pyle, and whose point already touched the inner tegument of 
the ovule. In many cases one of the nuclei again divided 
itself ; and so there were three nuclei. It ahvays seemed to 
me to be the posterior nucleus which had divided, and in the 
case of Orchis maculata I can state positively that it was the 
posterior one. As soon as the fertilisation is over, which 
can be seen by the changed condition of the envelopes in the 
embryo sac, no further traces of the nuclei are to be found. 
The whole end of the tube, whose point lies on the embryo 
sac, often separated by a cellulose plug on the outside, is al- 
together homogeneous and highly refractive. 
I may as well state here that I have brought ovules, 
which were capable of fertilisation, and tubes, when they 
(the tubes) were growing vigorously, together into one drop 
of saccharine solution; but that in no case could any entry 
of the tube into the micropyle be observed, not to speak of 
an act of fertilisation (Van Tieghem, 1. c., p. and 
Strasburger, 1. c., p. 486). I will begin the description of 
the stages of development in the Monocotyledons which I 
examined, with the following, which I found to be one of the 
best examples. 
Antliericum ramosum . — The Pollen-bodies of this species 
are almost semi-spherical. In a dry condition their convex 
side is deeply folded in. The extine is here very thin, and 
mostly broken through by the strong development of the 
intine, which later will evolve the tube. 
In examining flower buds of about 5 mm. in height Pollen- 
bodies are generally found in which the vegetative cell is 
already formed (Plate IV, fig. 1). It is very difficult in the 
case of this plant to observe in detail the various stages of 
division on account of the dense contents of the cells. There' 
is, however, no difficulty in ascertaining that the large circular 
nucleus places itself in the equatorial plain of the Pollen- 
body, and there divides itself. The result of the division is 
two cells. One, taking up by far the larger part of the 
Pollen-body, has a far larger nucleus, which is very like the 
original one, and like it has a very large nuclear body. The 
other, and far the smaller one, is attached to one side of tht' 
Pollen-body, and is separated from the sister-cell by a w'atch- 
