G68 
PROFESSOR F. 0. BOWER OR THE DEVELOPMENT AND 
that, as far as observation extends, the starting-point is in either case the same. If 
we leave the size of the tuber out of account, there is in the structure of the apex of 
the mature tuber no indication by which it has been possible to decide beforehand 
whether the tuber will produce sporangia or merely vegetative organs. 
Befoi'e entering on the details of the process of germination, it will be well to state 
what the results of that process are, as shown by mature plants. Of the twenty-two 
mature plants which were preserved in spirit, seventeen bore sporangia, five had only 
vegetative organs. From a careful comparison of them the following conclusions have 
been drawn, viz.:— 
(A.) Where sporangia are produced, the number of foliage leaves is 3-6 ; the 
number of roots 1-3, usually 3. Two tubers are found in all cases, one of these 
being the spent tuber of the previous year, the other the new tuber. 
(B.) Where sporangia are absent, the number of foliage leaves is 4-7 ; the roots 
1-2, usually 1. As before two tubers are present, and it may be stated that in no 
case have more tubers than two been observed : if it is constantly the case that only 
one new tuber is formed during each period of activity, it is obvious that there can 
be no increase in number of individuals by means of the tubers. 
Taking, first, the more simple case, where the germinating tuber produces only 
vegetative organs, the conical apex elongates, and a massive rounded outgrowth 
appears upon it: this is the first leaf. The position of this first leaf is lateral, 
though in some cases more clearly so than in others : its position relative to the 
parent plant which produced the tuber has not been found to be constant in those 
cases where it was possible to judge on this point; thus, it has been found in some 
cases to be inserted on the side of the axis more remote from the parent plant; 
again, it has been observed in other cases to be lateral as regards the parent plant. 
As will be pointed out below, the other organs developed later, have more or less 
clearly defined positions, relative to the first formed leaf, and consequently we may 
conclude generally, that as regards the position of its organs, the germinating tuber 
develops independently of the plant which produced it : this conclusion might well 
be anticipated since the parent plant is in a state of advanced decomposition before 
the tuber begins to germinate. Where the tuber is a small one, and the supply of 
reserve materials is therefore small, the leaf which appears first may be the only one 
developed : this has been the case in the plants represented in figs. 8 and 9 : in both 
of these, the solitary leaf is the most prominent member of the plant. I am not in 
a position to state definitely that in these cases the leaf is clearly of lateral origin 
on the apex of the tuber, though the natural conclusion would be that it is lateral, 
and this view is supported by a comparison with the other types of development of 
the plant, to be described below. 
In one irregular example represented in fig. 10, there are apparently two leaves of 
equal size. This case may be compared with that shown in fig. 20 at a more advanced 
stage of development. 
