334 SUMMARY OF CURRENT RESEARCHES RELATING TO 



divisions, Eusegagropila and Cornuta. A diagnosis of each subdivision 

 is followed by the respective key to the species in each group : — Eueega 

 gropila containing six species, C. Linnaei, C. Martensii, C. profunda, 

 C. holsatica, C. armeniaca, and G. Sauteri ; Cornuta contains as yet only 

 G. cornuta. Each species is then discussed separately, and two new 

 varieties are described : C. profunda var. Nordstedtiana, and G. Sauteri 

 var. Borgeana. Finally lists follow of insufficiently known forms, 

 among which is a new species, C. Dusenii, and of species removed from 

 the section. C. muscoides Menegh. is shown to be a species founded on 

 insufficient grounds, and is therefore struck out altogether. 



Spiral Arrangement in the Rhodomelacese.* — Dr. Kolderup Rosen- 

 vinge here enters into a full discussion of the views on this subject 

 held by Prof. Schwendener and his pupil H. Seckt, which he pronounces 

 incorrect. Dr. Rosenvinge holds that the spiral position of the " leaves " 

 {as he calls them) in the Rhodomeleae is not dependent upon any out- 

 side influence, but that the cause must be sought in the interior of the 

 plant. The author thinks that the position of each new "leaf" is 

 determined by the position of the last preceding one, possibly by means 

 of an impulse conveyed through the protoplasm which connects the 

 cells. He notes the correlation between the position of the " side- 

 organs " and that of the first-formed pericentral cell ; and he denies 

 any correlation between the direction of the leaf-spiral and the asym- 

 metrical branching of the leaves. The direction of the spiral is usually 

 to the left, and a change of spiral on any single shoot is extremely rare. 

 The divergence is not absolutely regular, but varies between i and f. 



Development of the Cystocarp in some Floridese.f — A detailed 

 account of the development of the fruit in two red algae, Heuretella 

 Scliousboei, and Chylocladia Jcaliformis, is given by A. Hassenkamp, illus- 

 trated by beautiful figures. The author shows that Prof. Oltmanns' con- 

 clusions concerning the absence of double fertilisation in the Florideae 

 hold good in these two species, and infers that similar results would be 

 obtained from an examination of other Florideae. Both this author and 

 Oltmanns find that the spores arise from division of purely sporogenous 

 nuclei, and that the auxiliary cell simply serves to nourish the sporo- 

 genous cells. The sporogenous nucleus never fuses with the nucleus 

 of the auxiliary cell, and thus the second fertilisation, which was be- 

 lieved to take place in the auxiliary cell, is fictitious. The author 

 regards this stage of development as a parasitism of the sporogenous 

 cell on the auxiliary cell, and likens it to the development of the sporo- 

 gonium of a moss on the sexual generation. He regards the antheridia 

 and the carpogone-bearing plant as the gametophyte, while the sporo- 

 phyte is represented by the sporogenous cells and filaments and by the 

 spores. In the same way that the sporogonium of a moss is nourished 

 by the sexual generation, so is the sporogenous cell nourished by means 

 of fusion with the auxiliary cell, since the egg-cell does not contain 

 sufficient food-material for the purpose. 



The author also criticises certain statements on the development of 



* Pringsh. Jahrb., xxxvii. (1902) pp. 338-64 (1 pi.). 



t But. Zeit, lx. (1902) pp. 67-86 (1 pi. and 12 figs, in text). 



