8(5 SUMMARY OF CURRENT RESEARCHES RELATING TO 



3. The solutions must bo completely neutral, and not poisonous. 

 Want of attention to this rule is a constant source of error. 



4. In doubtful cases the special characteristics of abnormal 

 plasmolysis should always be observed. 



Division of the Nucleus.*— W. Flemming gives in the ' Botanischo 

 Zeitung ' an exceedingly useful resume of the most recent contributions 

 of Strasburger f and Heuser \ to the literature of this subject, pointing 

 out the extent to which agreement has now been attained by various 

 observers, and the points in which they still diller, and which still 

 remain open to doubt. Flemming considers that one very valuable 

 result of these publications is that the controversy with regard to 

 indirect division of the nucleus has now ceased. 



Structure, Vital Phenomena, and Reactions of the Cell.§ — 

 C. Frommann describes the phenomena observed in a number of 

 different vegetable cells, and the changes which take place under 

 the influence of various physical and chemical agencies. 



The terminal cells of the glandular hairs of Pelargonium zonale 

 are filled with white or yellowish homogeneous granules, varying in 

 size and form, imbedded in a granular fluid which is usually traversed 

 by a larger or smaller number of threads ; these are sometimes 

 accompanied by rod-like structures of various forms, not unfrequently 

 combined together into nets. The nucleus is homogeneous or finely 

 granular, sometimes invested by a delicate envelope, and containing 

 a nuclcolus-like structure which the author calls the " granule." The 

 nucleus is frequently furnished with angular projections consisting of 

 a similar substance, which often pass through the surrounding proto- 

 plasm to the neighbourhood of the cell-wall. In many cells the 

 nucleus appeared to be altogether wanting. 



The changes are then described w'hich take place in these cells 

 by the action of a 1-2 per cent, solution of sugar, under which the 

 motion of the protoplasm continues for from one to three hoin-s. These 

 consist essentially in the change of form, size, and refrangibility of 

 the granules, in the formation of vacuoles, the commencement of con- 

 striction and division, the breaking up into smaller granules, and 

 their coalescence into larger structures. Induction-currents bring 

 about similar changes more rapidly. 



In the epidermal cells of the flower of Coreopsis hicolor two kinds 

 of graniile were observed, pale yellow and dark yellow, which the 

 author believes to bo simply pigments in various stages of dis- 

 organization. 



The cells of the epidermis and mesophyll of Sanseviera carnea 

 contain two kinds of nucleus, one refringent and of coarser structure, 

 the other paler and more delicate, though one of these kinds often 

 passes into the other. The internal structure of these nuclei is 

 described as exceedingly complicated. 



Very comj^licated is also the structure of the chlorophyll-bodies, 



* Bot. Ztg., xlii. a884) pp. 298-304. 



t Pec this Journal, iii. (1883) p. 227. t Ibid., iv. (1884) p. 407. 



§ Jcuaiscl). Zeitschr. f. Naturw., xvii. (1884) (3 pis.). Sec Bot. Centralbl. 

 xix. (1884) p. 68. 



