ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 673 



contrary to the assertion of previous observers, also in certain Florideaa 

 — Polysiphonia, Bhodomela. Where, therefore, a spiral phyllotaxis 

 occurs in the Florideae, it must be the result of the contact which 

 occurs in the apical region. 



Phylogeny of the Green Algae and Archegoniatae.* — K. Bohlin 

 proposes the following scheme for the relationships of the Green Algae 

 and Archegoniatae. 



The Chlorophyceae are descended from the Flagellata ; their iso- 

 gonids or zoospores are embryonal forms of the greatest phylogenetic 

 importance. The spermatozoids and the zoogonids have the same 

 number of cilia and the same systematic value. A second character of 

 great importance is the pigment and the product of assimilation of the 

 chromatophore. The pigments soluble in alcohol are of the greatest 

 systematic value ; while those soluble in water (phycoerythrin and phy- 

 cocyan), while determining the colour of the plant, do not influence the 

 product of assimilation. On these principles the green algae may be 

 classed under three groups, parallel to the Phaeophyceae, viz. : — 



(1) Heterocontse : — Product of assimilation oil; two unequal flagella. 

 Descended from the Chloromonadineae. 



(2) Chlorophyceae : — Product of assimilation starch. Descended from 

 several unknown or extinct types of green Flagellata. 



(3) Glaucophycese : — Blue-green like the Cyanophyceae ; but provided 

 with a nucleus and producing starch as the product of assimilation. 

 Descended from the Cryptomonadineae. 



The Vaucheriaceae are detached from the Siphoneae and placed 

 among the Heterocontae, with a probable descent from Vacuolaria, on 

 account of their agreement in the product of assimilation and in the 

 structure of the spermatozoids ; while the starch-forming Siphoneae 

 belong to Chlorophyceae. It is doubtful whether the yellow-brown 

 unicellular Algae at present known (Entodesmis, Phseococcus), belong to 

 the Phaeophyceae or to the Glaucophyceae. 



The Archegoniatae are probably derived from the starch-producing 

 Chlorophyceae, but not in one line of descent. The ciliation of the 

 spermatozoids shows that there must have been at least three lines, 

 which have developed into the Bryophyta, the Lycopodineae, and the 

 remaining Pteridophyta. 



Cryptogamia Vascularia. 



Root of Vascular Cryptogams.f — G. Chauveaud has made the fol- 

 lowing observations. 



In Equisetaceae the separation of the cortex and the stele takes 

 place, not merely before the separation of the external cortex ; it pre- 

 cedes all other septation, even the appearance of the radial longitudinal 

 septa which divide each of the three external segments into several cells. 

 The cortical or stelic elements, instead of being at first superposed on 

 the transverse plane, alternate with one another. The cortical segments, 

 eight or more in number, are arranged in a single layer, surrounding 



* Utkast. till d. grona Algernas o. Arkegoniaternas Fylogeni, Upsala, 1901. See 

 Bot. Ztg., lix. (1901) 2'" Abt. p. 234. 



t Comptes Rendus, cxxxiii. (1901) pp. 54-5. 



