SOME OBSERVATIONS ON ACINETARIA. 649 
watch-glass, and not under a coverslip. In a typical case a 
short. piece of hydroid was placed in a flat-bottomed watch- 
glass at 5 p.m. on Saturday, and the positions and appearance 
of all the Ophryodendron on it were carefully noted. The 
proboscidiform individual showed the commencement of the 
formation of a vermiform bud. On Sunday morning the 
vermiform bud was fully grown, but was still in direct con- 
tinuity with the proboscidiform. At 5 p.m. on Sunday the 
vermiform bud was active, and was almost free, and at 5.50 
p-m. it was quite free and attached to the hydroid stem. 
The young, free vermiform individual can travel consider- 
able distances-in a leech-like fashion, using its ends as 
suckers. The observations were repeated on other indivi- 
duals with the same result. ‘he internal details of this 
process of budding are shown in PI. 15, figs. 4 and 5. 
In Pl. 15, fig. 4, a proboscidiform individual is shown, in 
which the right apical lobe is prolonged, indicating the first 
stage in the formation of an external vermiform bud; on the 
left side there is a fully developed vermiform bud, which has 
not yet become free. 
In section it is easy to see that the bud is formed as a hollow 
outgrowth, a fact which explains the rapidity of the early 
stages in its development, as well as the enormous apparent 
disparity in mass which is sometimes seen between the bud 
and its proboscidiform parent. 
In Pl. 15, fig. 5, the last stage in the division of the macro- 
nucleus between the proboscidiform and the vermiform bud 
is shown. At this stage the vermiform individual is always 
much swollen at its apical end, and it is only later that the 
vermiform individual becomes elongated, and a distinct lip 
is developed round the anterior end. The young vermiform 
bud now becomes active, and finally pulls itself away from 
the parent individual. At this stage the vermiform indivi- 
dual creeps up the stem of the hydroid, finally becoming 
attached by its posterior end and developing its characteristic 
rod-like stalk. At first the stalk is quite short, and the 
greater length is hidden in the posterior end of the animal 
