LIFE HISTORIES OF FAMILIAR PLANTS 



several months as such, and seems to make little 

 or no progress ; however, during this time there 

 are mysterious happenings beneath its green frond. 

 Soon after the tissues have completed their growth 

 in area, some of the cells, in a thickened part of 

 the frond near the notch in its upper part, begin to 

 develop into curious flask-like structures that stand 

 out from the surface. Then lower down some 

 rounded bodies appear; Fig. 120 (Plate 86), just 

 shows the distinction between these structures, but 

 it needs high powers of the microscope to study 

 their details. 



Marvellous though it may seem, these are the 

 ^^ ovaries " and ^' stamens " of the fern — its repro- 

 ductive parts. Under this little green scale, just 

 visible to the eye, fertilisation has to take place. 

 The rounded bodies are known as antheridia, and 

 they produce within them a large number of 

 extremely minute, spirally-coiled sperms, termed 

 antherozoids. These little organisms are provided 

 with a tuft of delicate cilia by means of which, 

 when they are in water or in moist situations, 

 they are endowed with locomotion, wriggling like 

 eels, as they appear in myriads from the mature 

 antheridia. 



At the time they appear, the flask-shaped 

 structures (archegonia) secrete an acid fluid from 

 their mouths, which attracts the lively antherozoids 

 as they plunge about amongst the dew and 

 moisture beneath the prothallus ; thus they find 

 their way into the interior of the archegonium and 

 unite with the egg-cell ; in that manner fertilisation 



196 



