254 



FOUNDATIONS OF BOTANY 



300. Organs for Repro- 

 duction. — The fruiting 

 organs are to be sought 

 on the radiating branching 

 filaments and are usually 

 produced in great abun- 

 dance during the summer. 

 Various stages of develop- 

 ment may be expected at 

 a given time. The anther- 

 ozoids are small spheres 

 without cilia, non-motile, 

 with a thin cell-wall. Look 

 for cells in -which they are 

 formed (antheridia), occur- 

 ring in groups at the tips 

 of the branches. Compare 

 these with the vegetative 

 cells. , 



301. Spore -Production. 

 —Look for spore-producing 

 organs in various stages. 

 In the young stage at the 

 time of fertilization, an- 

 therozoids, carried by cur- 

 rents of water, may be 

 found adhering. Note the 

 shape of the tip (trichogyne) 

 and the base (carpogonium), 

 and find whether there is 

 any partition separating 

 them at this stage.- Draw 

 or describe a few later 

 stages in development, and 

 note the arrangement of 



the spores at maturity. Are they naked or enclosed in any sort of 

 envelope ? Are they arranged in masses, chains, or otherwise ? 



Fig. 187 Portions of Thallus of a Bed Alga 



(Chantransia). (Much magnified.) 



A, filaments with antheridia, a ; B, yovmg recep- 

 tive hair, or trwhogyne, t ; C and D, successive 

 stages in the growth of the clustered fruit,/. 



