536 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to 35° they frequently clevelope normally without any lime being 

 discoverable in the newly-formed organs. 



Occurrence of Iron in Plants.* — A. B. Griffiths finds that in 

 plants (the Savoy cabbage) grown in soils without any artificial addi- 

 tion of iron salts, the ash contains iron, the leaves yielding a very 

 much larger percentage than the stalk. If feri-ous sulphate is added 

 to the soil, the proportion is greatly increased. Microscopical exami- 

 nation showed that in the protoplasm of the chlorophyllaceous cells 

 there were minute crystals (not crystalloids), sometimes solitary, 

 sometimes an-anged in groups round a common centre. These were 

 easily proved by chemical tests to be crystals of some salt of iron, 

 probably ferrous sulphate ; they belonged to the monoclinic system, 

 and their composition was probably FtiS04 + 7H20. They occur in 

 plants grown in natural soil, but are much more numerous in those 

 grown in iron-manured soil. They were also found near to the chloro- 

 phyll corpuscles, and the author suggests that they may act as reserves 

 for the formation of the green colouring matter of chlorophyll. 



B. CRYPTO SAMIA. 



Palseontological Development of Cryptogams.! — Saporta and 

 Marion trace the fossil remains of Siphonaceous Algfe back to the 

 Lower Silurian period. The higher algae, they consider, do not make 

 their appearance till comparatively modern times, partly in the 

 Jurassic ; the Characeaa, Floridese, Phseosporese, and Fucaceas in the 

 Tertiary, 



The flora of the dry land developed entirely from aquatic Proto- 

 phyta. The Musci and Hepaticfe constitute a lateral branch, the 

 main stem producing in succession the Filiccs, Ehizocarpefe, Lycopo- 

 diacefe, GymnospermiD, and Angiospermfe. The primary and secondary 

 strata furnish no remains of mosses, probably because they are entirely 

 of marine or brackish origin. From a primary fern with undiflferen- 

 tiated sporangia, sprang the Filices, Lygodiacese, and Marattiaceae. 

 The latter have existed from the Carboniferous period ; the Lygo- 

 diacea) do not make their appearance till the end of the Cretaceous 

 period. The Cyatheaceas date from the commencement of the Carboni- 

 ferous period, the true Polypodiacese only from the Ehfetian. The 

 Lycopodiacea3 with isosporous sporangia may be an independent branch 

 from the Protophyta, and appear as early as the Devonian ; the Hete- 

 rosporje are more highly differentiated Isosjiorae, having their highest 

 development in the Lepidodendra of the Carboniferous period, and 

 then degenerating to the Selaginellea) and Isoctcfe. The most highly 

 developed Cryptogams are the Rhizocarpeae, to which belong the 

 Ehfetian Sagenopteris and the Carboniferous Splienophyllum. 



The Cryptogams form therefore, according to these authors, a 

 main branch of the vegetable kingdom, which has sprung directly 



* Journ. CI. em. Soc, xliii. (1883) pp. 195-7. 



t Saporta, G. dc, and Marion, A. F., ' Die palaeontologische Entwicklung 

 des Pflanzonreiches. Die Kryptogamen.' 250 pp., Leipzig, 1883. See Bot. 

 Ceutralbl., xiii. (1883) p. 411. 



