4 Humphrey . — The Development of the 
1 aril,’ though not universal throughout the Scitamineae, is yet 
so general that the group has also been called 4 Arillatae! 
The changes undergone by the ovule from its first appear- 
ance to the time of fertilization, and the subsequent growth 
and differentiation which takes place normally in response to 
the stimulus of sexual union, have been studied in detail in 
many seeds, so that the features of seed-development in 
general are well known. But observations of this sort relating 
to the group under consideration are few and fragmentary. 
They have been made chiefly on species of Canna , which is 
the only Scitamineous genus whose members thrive and 
perfect seeds in the summer climate of our temperate lati- 
tudes. Some of the interesting details of seed-development 
in this genus have already been noted, but chiefly incom- 
pletely or incidentally, so that they have remained little 
noticed. As already intimated, the independent discovery 
of these striking features has led to the present comparative 
studies, in the hope that some light might be thrown on the 
phylogeny of the group and the origin of the peculiarities 
of Canna . Although the result is less satisfactory than could 
be wished in this respect, certain features are shown to be 
probably common to the Scitamineae, and certain interesting 
phenomena show how widely the details of seed-development 
may vary within the limits of a family. 
The work has been done chiefly by freehand sectioning. 
Since the cell-contents were often not important for the 
question in hand, rather thick sections could be cleared with 
Javelle water. Indeed, the relations of tissues could often be 
better made out on such sections than from thinner ones. For 
special points microtome-sections were necessary, but as a 
rule they have offered no advantages over those more easily 
prepared. 
Though Canna proves to be the most aberrant in its seed- 
development of all the genera examined, yet, since it was 
first and most exhaustively studied, its development may 
be first described. This genus contains, according to the 
estimates of different monographers, from thirty to sixty 
