1.] MICROSCOPIC PLANTS. 15 
Its name is of the same alarming proportions as those 
we have previously experienced ; it is the Penzccllium 
glaucum. It consists of a number 
of cells, like Torula, drawn out ~ 
into an oblong form, and placed 
end to end. Each of these cells 
has the same structure as Torula, 
consisting of a cell-wall, and pro- 
toplasmic contents. As these cells 
grow, cell-walls are formed trans- 
versely, and thus the number of 
cells increased. The string of cells 
so formed is termed a kypha. They 
run along horizontally, sending 
off at intervals branches, some of which penetrate 
downwards into the substance on which the plant is 
growing, and some rise upwards into the air. The 
descending branches are termed the submerged hypha, 
the ascending aerial hyphe, whilst those which run 
along the surface form a network, and are known as 
the mycelium. ‘The submerged hyphe serve as roots 
to nourish the plant, and the aerial hyphae, when 
they have reached a certain height, produce at their 
summits a chain of round cells very like Torule. 
These are the spores. They serve the same purpose as 
—though they must not be confounded with—seeds, 
that is, to produce other plants like that on which 
they were formed. When a spore falls upon a suit- 
able surface, the cell-wall is pushed out at one or 
more points, and each protuberance lengthens into a 
long tube or hypha, divided at certain distances by 
cross partitions. From this ascending and descend- 
