136 SUMMARY OF CUERENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including- Cell-contents. 



Nature and Significance of the Chondriome. — A. GtUilliermond 

 {Compt. Rend., 1918, 166, 649-651). A short note upon the chon- 

 driome, which the author regards as a c onstituent element of all cells, 

 whether of animal or vegetable origin. The chondriome is represented 

 by mitochondrias, which exist as minute bodies in the homogeneous 

 cytoplasm, distinguishable from the latter by their greater refractive 

 power. They are granular or in the form of short rods or filaments, 

 sometimes elongated and of undulate outline, more rarely branched. 

 They are the most fragile parts of the cell and are especially sensitive to 

 osmotic influences. In a hypotonic medium the granular mitochondrias 

 swell and form large, aqueous vesicles, while the chondriocontes break up 

 into granules and subsequently form similar vesicles, but it is easy 

 to prove that these formations do not represent the normal evolution of 

 the mitochondrias. 



Researches as to the nature of both animal and plant mitochondrias 

 show that they are living entities, capable of reproduction by division ; 

 during mitosis the chondriome divides into two portions, one of which 

 passes to each pole. The mitochondrias give rise to the greater 

 part of the secretory products of the cell, and are entirely similar in 

 character to the well-known plastids. 



In general the chondriome of the plant-cell is represented in the egg 

 by granular mitochondrias ; in the embryonic cells a portion of these 

 elements is transformed into chondriocontes, which subsequently 

 develop into plastids ; others retain the granular form and assume other 

 functions, or simply serve for the perpetuation of the chondriome. 



S. G. 



Constancy of Cell-Shape. — L. A. Tenopyr {Bull. Torr. Bot. Club, 

 1918, 45, .51-76, 1 fig.). The author has studied the relative length 

 and breadth of leaves and their constituent cells in three types of plants 

 — viz. (1) species with broad basal leaves, narrow stem-leaves and tran- 

 sitional leaves, represented by Camimnula rotundifolia and Lobelia 

 Erinus; (2) broad and narrow-leaved species belonging to the same 

 genus, such as Plantago major and P. lanceolata ; (3) varieties of the 

 same species having entire leaves as compared with others having lobed 

 leaves, such as ai-e found in Cichorkmi Intyhus. 



The cells of the plants examined show considerable variability in 

 size in the same tissue, but the average cell-size for any one tissue of a 

 species or variety is a fairly constant and hereditary character. The 

 cell-size of closely related species may be the same, but may differ con- 



