Campbell. — Studies on the Araceae. 667 
peculiarities, both in the formation of the endosperm, and in 
the behaviour of the antipodal cells. Some of them, like 
Arisaema triphyllum 1 , differ also from the usual angiosper- 
mous type, in the character of the archesporium. The arche- 
sporium in this species shows in cross-section from two to four 
or five cells, which, according to Mottier, are the product of 
the division of a single primary archesporial cell. It seems 
probable, however, that sometimes, at least, these cannot all be 
traced back to the division of a single primary archesporial cell, 
but arise from two or more independent sub- epidermal cells. 
A similar archesporium has been found by the writer in 
Aglaonema commutatum . and it is quite probable that further 
research will show the same thing in other Araceae. 
Hofmeister 2 showed that in nearly all the Araceae ex- 
amined by him the endosperm at an early period fills the 
embryo-sac with a continuous tissue, or in some cases leaves 
a greater or smaller portion of the cavity permanently empty 3 . 
He however misunderstood the process of cell-division by 
which the endosperm is formed, and supposed that in all cases 
there was a ‘ free cell-formation 5 preceding the formation of 
the solid endosperm. It is true that in Pothos longifolia he 
found frequently an early division by a transverse cell-wall ; 
but he infers that the subsequent endosperm formation, which 
he says is confined to the upper and larger of the two primary 
cells, is formed by ‘ free cell-formation,’ and not by successive 
cell-divisions, as is probably the case. A type of endosperm 
formation somewhat similar to that of the Araceae has been 
described by Strasburger 4 for Ceratophyllum. In this case, 
however, the first division-wall in the embryo-sac divides it 
into equal parts. 
Hofmeister called attention to the large size of the antipodal 
cells in some species of Arum , and the writer has found in 
Lysichiton a remarkable development of the antipodal cells 
1 Mottier, Bot. Gazette, 1892. 
2 Neue Beitrage zur Embryobildung, &c. ; Monocotyledonen. Leipzig, 1861. 
3 1. c. p. 704. 
* Ein Beitrag zur Kenntniss von Ceratophyllum submersum , Pringsheim’s Jahrb. 
fur wiss. Botanik, xxxvii. 564, 1902. 
