I.J 



MICROSCOPIC PLANTS. 



FIG. 16. 



Its name is of the same alarming proportions as those 

 we have previously experienced ; it is the Penicillium 

 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, ancl 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 hypJia. 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 hyp/tee, 

 the ascending aerial hyp/ice, whilst those which run 

 along the surface form a network, and are known as 

 the mycelium. The submerged hyphae serve as roots 

 to nourish the plant, and the aerial hyphse, when 

 they have reached a certain height, produce at their 

 summits a chain of round cells very like Torulae. 

 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- 



