ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 



by observations on other plants such as Lilium, Cobwa, Gladiolus, Pinus, 

 Maris, &c, are as follows. The typical nucleus of the higher plants is a 

 water-cavity structurally similar to that of the cell-vacuole. The chroma- 

 tin is the only permanent constituent of the nucleus ; the karyolymph, 

 linin, nucleoli, and membrane are renewed with each succeeding mitosis. 

 The nuclear membrane originates like the tonoplast. It is formed by 

 the cytoplasm coming in contact with the karyolymph just as the 

 tonoplast is formed by the cytoplasm coming in contact with the cell- 

 sap. The karyolymph is no more permanent than the cell-sap, and 

 the nuclear membrane is no more permanent than the tonoplast. As 

 the nuclear membrane is of cytoplasmic origin, it is regarded as the 

 inner limiting membrane of cytoplasm rather than as a constituent of 

 the nucleus. Although the chromatin granules found in the cells of the 

 Cyanophyceaa and bacteria are surrounded by neither karyolymph nor 

 membrane, these granules nevertheless represent the nucleus, since 

 every highly organised nucleus passes through a stage in its develop- 

 ment when it consists of nothing but chromatin. It is further suggested 

 that the primitive nucleus probably did not secrete a karyolymph, and 

 therefore no nuclear membrane was formed. 



Effect of Temperature on Growing Cells.* — F. R. Schrammen, 

 following Hobbes who investigated the effect of temperature on the 

 •cells of the root-apex of Vicia Faba, has made parallel observations on 

 the stem-apex of that plant. His experiments confirm the physiological 

 and morphological distinction of the cytoplasm into tropoplasm and 

 kinoplasm, for these two cell-constituents have a different maximum 

 and minimum for their action and probably a different optimum. His 

 observations point to the spindle-fibres being, not mere lines of force 

 or paths of movement for the chromosomes, but definite threads of con- 

 siderable rigidity which are able to actively move the chromosomes. 

 The behaviour of the nucleolus points to its being a body of reserve 

 material, chiefly kinoplasmatic. Divisions of an apparent amitotic 

 nature were often observed, these were really the effect of unsuitable 

 temperatures on actual karyokinesis. Another abnormal result of high 

 and low temperatures was to cause the nuclei of some cells to become 

 pressed through the fine pores in the wall. 



Structure of the Starch-Grain.t — H. Kraemer concludes that the 

 starch-grain consists of colloidal and crystalloidal substances arranged 

 for the most part in distinct lamellse. At the point of origin of growth, 

 and in the alternate lamellae, the colloidal predominates associated with 

 the crystalloid cellulose, whereas in the other layers the crystalloidal 

 substance, consisting for the most part of granulose, preponderates. 

 The peculiar behaviour of the colloidal layers towards anilin-stains is 

 analogous to the behaviour of a section containing mucilage-cells towards 

 these dyes, the latter being taken up by the mucilage-cells alone. 

 Again, as the characteristics of mucilage-cells are most pronounced in 

 anhydrous media, such as concentrated glycerin, so a similar effect is 

 seen in the starch-grain. The reason that the crystalloidal character of 



* Verhandl. naturhiBt. Vereinu, lix. (1902) pp. 49-95 (1 pi.). 



f Bot. Gazette, xxxiv. (1902) pp. 341-54 (1 pi. and figs, in text). 



