ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 707 



Meaning of Mycorhiza.* — Herr E. Stabl discusses, with great 

 wealth of detail, the vital phenomena which accompany respectively the 

 presence and the absence of ectotrophic or endotrophic mycorhiza, enu- 

 merating all the classes of plants in which it is known to exist. While 

 there are some natural families in which the presence of mycorhiza is 

 at present entirely unknown — Cruciferse, Cyperacese, Polypodiacese — 

 the author considers it probable that the greater number of the higher 

 plants are capable, at least under certain circumstances, of entering into 

 this symbiosis with fungi. 



The explanation given by the author of the occurrence in the same 

 forest, of plants which do, and plants which do not obtain their nourish- 

 ment in this way, is that the difference is accompanied by a difference 

 in their facility for absorbing saline food-material. Plants with a 

 powerful transpiration current can dispense with the formation of myco- 

 rhiza ; while those in which the transpiration is only feeble can obtain 

 a sufficient supply only with the assistance of the symbiotic fungus. 

 Indications of strong transpiration are afforded by the excretion of drops 

 of water, rapid withering when cut, and the abundant formation of starch 

 in leaves exposed to the light ; feeble transpiration, on the other hand, 

 by the absence of exuded water and the abundant formation of sugar. 

 Autotrophic plants furnish, as a rule, a larger proportion of ash than 

 mycotrophic. 



A very interesting comparison is drawn between mycotrophic, para- 

 sitic, and carnivorous plants; all these phenomena being devices for 

 attaining the same end. 



Protophyta. 

 a. Schizophycese. 



Glceocapsa alpina.f — Herr F. Brand gives a detailed account of the 

 structure and life-history of this rare Alpine alga. The following are 

 given as new results. The cell has only a very thin membrane, not 

 usually discernible, and not separable from the cell-contents. The 

 gelatinous envelope which surrounds the cell is covered by a cuticle. 

 The size of the cell varies much more than has hitherto been supposed. 

 The cell-contents appear to be sometimes homogeneous, sometimes 

 granular ; the colour is bluish-green varying greatly in its tint. The 

 gelatinous envelope with its cuticle corresponds to the sheath of the 

 filamentous Cyanophyceae ; it is not formed by swelling of the cell- 

 membrane, but is excreted from the cell. Under certain conditions it 

 becomes stiff and thin. In the vegetative condition the colony has only 

 a single general cuticle, which never encloses more than two complete 

 generations of daughter-colonies. The external appearance of the 

 organism varies so greatly in many respects that all the blue-violet 

 species hitherto described, and some also of the colourless species, must 

 be regarded as forms of G. al/pina. 



Besides the coloured and the colourless states hitherto known, Glceo- 

 capsa alpina occurs also in three others:— (1) the dry state, an imperfect 

 resting condition, with very thin dry envelope, and usually smaller cells 

 and colonies; (2) the persistent state, with dark red or brown-violet 



* Pringsheim's Jahrb. f. wiss. Bot., xxxiv. (1900) pp. 539-668 (2 figs.), 

 f Bot. Centralbl., lxxxiii. (1900) pp. 224-36, 280-6, 309-13 (9 figs.). 



