85 



plant," occasionally offered for sale as a curiosity. S. rupcstris 

 probably behaves in the same way. 



In the neighborhood of Stanford University, a common fern 

 is Gyinnogramnic triangularis, commonly known as " gold-back 

 fern," from the yellow powdery secretion on the lower side of 

 the leaf. This fern dries up in summer without the leaves dying 

 down as they do in most ferns during the resting season. If a 

 leaf from Such a dricd-up specimen is placed in water, it will in 

 a short time absorb water through its superficial cells, and soon 

 becomes fresh and active. That this absorption of water is by 

 the lamina of the leaf, and not through the petiole, may be 

 shown by placing the dry leaf in water with the cut end of the 

 petiole completely out of water. The leaf will soon become 

 turgescent although it is quite impossible that any water could 

 have been taken up through the cut end of the petiole. Large 

 prothallia of this species (and perhaps of some other ferns) are 

 often met with in the autumn, before there possibly can have 

 been a development of these from germinating spores. To test 

 the abilit)' of the prothallium to endure complete drying up, 

 Dr. Peirce made a culture from spores of Gyinnogrannnc in the 

 laboratory, and the prothallia thus grown were allowed to remain 

 entirely dry during the whole summer of 1903. These were 

 given water in the fall and proved to have survived the summer 

 perfectly, numerous young plants developing later from these 

 prothallia of the former season. 



Goebel* has recorded from an allied fern Aiiogramvic, of 

 Southern Europe, perennial prothallia which develop tubferous 

 structures not unlike those of certain liverworts. Whether an}- 

 of our native ferns develop similar structures remains to be 

 seen. 



Some years ago, the writer received from San Diego, plants of 

 a Sclagi)iclla — probably 5. Bigelovii — with the earth in which 

 they had grown. The latter contained a good man\- spores that 

 had fallen from the plants, and earth, which had been kept dry 

 through the summer was well watered and in a ver}' short time 

 young plants appeared. Unfortunateh', none of the ungerminated 



*/. c, p. 426. 



