660 Lewis. — The Life History of Griffithsia Bornetiana . 
The fusion nucleus divides once in the auxiliary cell, and the two 
nuclei come to lie in the opposite ends of the now somewhat elongated cell 
(Fig. 83). Between them lies the greatly enlarged central nucleus originally 
present. Each of the nuclei resulting from the division of the fusion 
nucleus usually shows the characteristic double nucleolus. The auxiliary 
cell now divides, one daughter-cell containing the enlarged central nucleus 
and a single fusion nucleus, and the other containing only a fusion nucleus 
(Fig. 84). The latter may be called the placental cell ; from it the 
sporogenous lobes usually arise. Fig. 86 shows clearly that sporogenous 
lobes may also be formed from the auxiliary cell after the placental cell 
has been formed ; the nuclei entering these lobes are derived from the 
fusion nucleus. Very similar behaviour has been observed by Hassencamp 
( 40 ) in the auxiliary cells of Thuretella and Chylocladia. 
During these changes, the large nucleus of the auxiliary cell continues 
to increase in size. It becomes almost empty of contents, the nuclear 
outline becoming less and less distinct, and finally the nucleus disappears in 
the cytoplasm. 
Changes also take place in the other elements of the young cystocarp. 
The central cell, which at first contains a large central vacuole, becomes 
filled with homogeneous cytoplasm and with numerous nuclei formed by 
the multiplication of those originally present (Fig. 81). From the sides of 
the basal cell of the procarp soon after fertilization several small cells are 
cut off successively. These in turn divide, and the outer cell becomes an 
involucral ray (Fig. 85). Three to seven involucral rays are formed ; they 
are of various sizes and ages, and curve up over the cystocarp so as to 
cover it almost completely, except at the top. The structure of the 
involucral rays offers nothing especially remarkable. They are distended 
sacs, pale pink in colour owing to the presence of a small number of 
chromatophores. A thin layer of protoplasm bounds a very large vacuole. 
The nuclei may become quite numerous, 87 having been counted in a ray of 
average size. The rays do not form a definite pericarp, as they are not 
united at the sides. None are produced between the cystocarp and the 
vegetative cell which bears it, 
The placental cell formed at the division of the auxiliary cell increases 
in size and in number of nuclei, all of which are the product of the division 
of the fusion nucleus. Small protuberances are formed on its free border, 
each of which contains a single nucleus (Figs. 85, 86). Each protuberance 
is cut off from the mother-cell by an arched membrane, and the cells so 
formed give rise by repeated division to the sporogenous cells from which 
the carpospores are formed. 
While this is taking place, there is a general fusion of cells in the 
centre of the cystocarp. The following cells take part in this fusion : The 
placental cell, the auxiliary cell, the central cell, and sometimes the 
