486 STTMMAKY OF CURRENT RESEARCHES RELATING TO 



tissues are rendered inactive by excess of heat or by deficiency of nitro- 

 gen. A well-defined separating tissue is found, however, at the base of 

 the petals, and here at the time of fall there is a sudden increase in 

 turgeseence accompanied by increase in volume in response to external 

 stimulus. This would appear to point to a phenomenon similar in 

 character to those of sleep-movements, response to light, etc. 



CRYPTOGAMS. 



Pteridophyta. 



(By A. Gepf, M.A. F.L.S.) 



Relation of Woodsiese to Cyatheacese and Polypodiacese.* — 0. 

 Schlnmberger gives an account of the characters of the families, Cya- 

 theaceee and Polypodiacefe, and of the relation of the Woodsiege to both 

 families. He takes into consideration all the known characters of the 

 gametophyte and sporophyte of the genus Woodsia. 1. The antheridia 

 of Woodsia normally open by means of an apical lid-cell. 2. Hence 

 the difference in this respect supposed to exist between the Cyatheacege 

 and Polypodiaceae falls through. ?>. The only important difference in 

 the antheridia of these two familes lies in the structure of the lid-cell. 

 4. In Diacalpe aspidioides and Woodsia obtusa the antheridia have a 

 divided lid-cell. 5. The antheridial wall-cells play an active part in the 

 opening of the antheridium. 6. In the Woodsia prothallium occur 

 transitions between the characteristic hairs of the Cyatheacege and the 

 glandular hairs of the Polypodiacege. 7. The appearance of the pro- 

 thallium when mature depends upon the conditions of nutrition during 

 youth. Thus, moist-grown plants become crisped, while dry-grown 

 plants form adventitious prothallia. 8. Under the influence of weak 

 light, filiform adventitious prothallia can be made to produce branched 

 filaments with antheridia. 9. By special conditions of culture, pro- 

 thallia, which would produce normal embryos, may be induced to put 

 out apogamous shoots. 10. In structure of sporangium and in posi- 

 tion of annulus, the Woodsiege examined agreed absolutely with the 

 Polypodiacege type, with the exception of Diacalpe, which approaches 

 Cyatheacege in the characters of its annulus. 11. In the Woodsiege 

 there is a reduction of the receptacle in the formation of the sorus. 

 In Peranema the receptacle is stalked : in Diacalpe it is much re- 

 duced ; in Woodsia obtusa the sporangia are formed on a slightly 

 prominent hump ; in W. ilvensis they are formed on the unchanged 

 epidermal surface. 12. The indusium in Hypoderris arises out of a 

 closed superficial ring ; in Woodsia obtusa the ring is open towards the 

 margin of the frond ; in JI r . ilvensis the indusium arises out of single 

 hairs, which later are raised upon a common base. 13. The indusium 

 of Gystopteris fragilis is developmentally not to be regarded as inferior. 

 14. An indusium can only be inferior when it arises below the sporangia 

 on the receptacle. 15. The Woodsiege examined are all dictyostelous. 

 16. The muciferous canals of the Cyatheacege and Dicksoniea? arise by 

 the mucous degeneration of the septa in a series of cells. 



* Flora, cii. (1911) pp. 383-414 (figs.). 



