594 SUMMARY OF CUREENT RESEARCHES RELATING TO 



Muscineee. 



Variations in Sphagnum* — C. Jensen discusses the causes of the 

 great disposition to vary displayed by the different species of Sphag- 

 num, and attributes it, in the first place, to the influence of water, 

 and secondarily to variations in the light, temperature, and in the 

 nature of the soil. 



When the plant grows completely submerged, all the parts are 

 larger and longer ; the stem-leaves become larger, as also do their 

 hyaline cells, which are often provided with pores and spiral thicken- 

 ings; these leaves then resemble those of the branches in their 

 structure. Those branches which depend from the stem, forming an 

 envelope round it, lose this structure and grow like the other branches, 

 the fertile branches become longer, and are often inserted at a 

 greater distance below the apex of the stem ; the bundles of the 

 branches stand at a greater distance apart. 



Plants growing in a dryer situation are, on the contrary, more 

 compact, with shorter stems and crowded short erect branches with 

 closely adpressed leaves, as is especially seen in arctic forms. 



When the moss grows in the shade it is of a brighter green and 

 stronger growth. The fertile branches may be inserted beneath the 

 apex of the stem, and are then somewhat elongated. 



Forms sometimes occur with sickle-shaped branches, and others 

 which resemble the extra-European species in having the stem-leaves 

 of nearly or quite the same structure as those of the branches. These 

 usually occur in dry places, but sometimes also in water. 



Fungi. 



Sexual Heproduction in Fungi.f — H. M. Ward gives an elaborate 

 resume of the facts at present known respecting sexual reproduction 

 in the various classes of fungi. He points out that — at all events if 

 the Basidiomycetes are set aside — the absence of sexual organs 

 appears to be in direct proportion to the degree of parasitism deve- 

 loped by the fungus. There can be no doubt that the efficacy of any 

 act of impregnation depends on some essential difference in the nature 

 of the protoplasm of the two cells ; that, in an oosphere, for example, 

 the molecular energy of the protoplasm is less than that of the rest of 

 the plant for the time being, and that the access of the antherozoid 

 reinvigorates the sluggish mass, causing the renewal of active life. 

 The dormant interval which frequently intervenes between impregna- 

 tion and germination may be occupied by molecular rearrangements 

 in the mass. The difference in the nature of the male and female 

 protoplasm is indicated by the attractive force which the female 

 frequently appears to exercise on the male element, as in the case of 

 CEdogonium. The reinvigorating effect of the male protoplasm may 

 last through many generations. The fact of the sexual organs having 



* Bot. Tidsskr. Kjobenhavn, xiii. (1883) pp. 199-210. See Bot. Centralbl., 

 xvii. (1884) p. 267. 



t Quart. Journ. Micr. Sci., xxiv. (1884) pp. 262-310. 



