In other orchids the threads cohere at one end of the pollen-masses; and this forms the first or nascent trace of a caudicle.

That this is the origin of the caudicle, even when of considerable length and highly developed, we have good evidence in the aborted pollen-grains which can sometimes be detected embedded within the central and solid parts.

With respect to the second chief peculiarity, namely, the little mass of viscid matter attached to the end of the caudicle, a long series of gradations can be specified, each of plain service to the plant.

In most flowers belonging to other orders the stigma secretes a little viscid matter.