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 ? 



B C 



FlG. 187. Portions of Thallus of a Bed Alga 

 (Chantransid). (Much magnified.) 



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

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

 stages in the growth of the clustered fruit,/. 



