82 THE NATURE-STUDY OF PLANTS 
to rest and is kept moist, it is only a matter of time for 
the water to dissolve the air in the spaces or depressions ; 
and hard as it is to wet a sculptured seed, it is just as 
difficult when it is once thoroughly soaked to dry 
it again, except by allowing the water to evaporate. 
Thus the sculpture probably secures a dry dispersal 
period as surely as it ministers to the retention of 
moisture for germination at its close. 
As already mentioned, the seeds of some plants 
become slimy by the secretion of a mucilage when 
moistened, and when they dry they stick to dead 
leaves or the soil : the common Plantain is one of them. 
Those that adhere to the soil secure a certain amount of 
anchorage, but those that are upon dead leaves have 
a chance of greater things, for it is a matter of very 
easy observation that dead leaves are always being 
dragged underground by worms. Hence the mucilage 
may secure not only dispersal as already pointed out, 
but also being sown and anchored in a suitable place. 
The seeds of most plants, however, have so far as I 
know no special contrivance for adequate burial, but 
depend upon drift for being covered over. The 
student should, however, bear this necessity in mind, 
for it is one of real importance, and it is surprising how 
much still remains to be found out about plants which 
every one at all interested in Botany knows well 
enough by sight and perhaps by name, without, I 
am sorry to say, knowing much, if anything at all, 
about their life-history. 
The Ivy-leaved Toadflax, for example, is to be 
seen commonly on old walls in many parts of the 
country : on one in my own garden it thrives in pro- 
fusion, and it is one of the few species that has learnt 
to sow at any rate some of its seeds, in the crannies 
