Reproduced from 

 "Students' Text 

 Book of Zoology" 

 (Sonnenschcin). 



A CHAIN OF 

 FLAT - WORMS 

 PRODUCED BY 

 FISSION, AS 



YET INCOM- 

 PLETE 



(After Graff.) 

 o, o, mouth open- 

 ings. 



SORI OR SPORE-CASES ON FERN (POLYSTICHUM) 



On the back of fern fronds, little brown spore-cases may be seen which 

 burst open when dry and scatter numerous spores which, on germination, 

 produce prothalli. 





PROTHALLUS OF FERN: ORGANS PRODUCED 

 FROM SPORE OF FRONDS 



Showing archegonia (female organs) and antheridia 

 (male), together with rhizoids (roots) on under side. 

 (Greatly enlarged.) 



L 



Photos: J. J. Ward. 



PROTHALLI (NATURAL SIZE), ON WHICH ARE 



SEEN DEVELOPING THE YOUNG FERNS 



WITH THEIR FIRST FRONDS 



