914 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



these after attaining certain dimensions contract more or less at the 

 point of attachment to the body so as to be sharply distinguished 

 from it by a circular furrow. They sometimes form an annular 

 swelling. The author considers that he has established with "a 

 certainty nearly complete " that they give rise to new individuals. 

 Multiplication also takes place by a species of transverse fission. 

 The other species described is Giardia agilis Kiinst.* 



BOTANY. 



A. GENERAL, including Embryology and Histology of the 

 Phanerogainia. 



Observations on Vegetable and Animal Cells.t — In the first 

 part — the only one yet published — J. M. Macfarlane deals with the 

 vegetable cell, and especially with that of Chara fragilis. The author 

 has already shown that a nucleolus and a nucleolo-nucleus, or (as he 

 now, at Prof. Kutherford's suggestion calls it) an endonucleolus, are 

 essential parts of every growing vegetable cell. In stages where 

 there are several nuclei, Mr. Macfarlane found that staining in eosin, 

 &c., with previous decolorizing of the preparations, enabled him to 

 see the nuclei better than with the osmic acid process. No definite 

 observations were made on the endonucleus of Chara, on account of 

 its having been too deeply stained. In every active embryonic cell, 

 only one nucleolus is present in the resting state, and the action of 

 reagents and its thick and viscid nature indicate that it is a vesicle 

 containing richly differentiated protoplasm. The nuclear spindle or 

 barrel is regarded as being merely a scaffolding thrown across the 

 space between the halves of the dividing nucleus, and so helping 

 the protoplasm in its work of depositing the septum. No definite 

 spindle is to be seen in Chara. 



There appears to be evidence that in all plants the multinucleolar 

 is succeeded by a multinuclear condition, and the author regards it as 

 a general principle that, after cell-formation has ceased, the cell- 

 contents (especially the endonucleus and nucleolus) persist in their 

 activity for a shorter or longer period ; and this activity depends on 

 the condition of nutrition of the cell. 



In summing up, Mr. Macfarlane says, " It will be seen that I regard 

 the building-up of cells to form a definite plant or the parts of it, 

 as the result of a force radiating from the cell-centre, stimulating to 

 division ; and either that the energy giving rise to this force is equal 

 to producing only a certain amount of tissue, or that it is inhibited 

 or resisted by some external force, which prevents it forming an 

 excess of tissue, when this would tend to pathological change, or to 

 loss of individuality in the plant. The most exalted type of cell is 



* See this Journal, ii. (1882) p. 804. 



t Trans. Koy. Soc. Edin., xxx. (for 1881-2) pp. 585-95 (1 pi.). 



