204 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including Cell-Contents. 



Mitochondrias of Plant-cells."' — A. Guilliermond publishes a reply- 

 to some of the objections made to recent theories as to the nature and 

 function of the mitochondrias of plant-cells. The writer endeavours to 

 show that the plastids of plant-cells are of the same nature as the mito- 

 chondrias of animal-cells, and that such being the case, they are 

 *' organisms of elaboration." After prolonged study of these structures 

 in the cells of Tulipa and Iris germanica, the author is convinced that 

 they are identical with those found in animal-cells. They fall into two 

 categories — viz. short, granular or rod-like bodies, which usually represent 

 a purely vegetative or resting stage ; or elongated, thin, flexuose chon- 

 driocontes having the power of elaborating pigment, starch, or fat. When 

 osmotic equilibrium is disturbed these latter structures swell and assume 

 the form of vesicles or vacuoles with a thick wall enclosing an aqueous 

 liquid with numerous refractive granules held in suspension. The author 

 points out that these observations are identical with those made by 

 zoologists in connexion with animal-cells. Moreover the behaviour 

 towards staining reagents is the same. Finally, it appears as a result 

 of the present work, that the so-called plastids of plant-cells are of the 

 same nature as the mitochondrias, and share the elaborating functions of 

 the latter. They are not to be regarded as organisms restricted to 

 chlorophyll-producing cells, biat as definite organisms of the cytoplasm 

 and the seat of most diverse elaborations both in plant- and animal-cells. 



Nature and Function of Chondriomes.f— P. A. Dangeard pubhshes 

 a summary of his observations, based upon several years' study of chon- 

 driomes, which induce him to discredit the theories of those writers who 

 regard chondriomes as living entities giving rise to the various plasts and 

 to cell-contents such as starch, oil, etc. According to the author, the 

 cell encloses (apart from the nucleus) two " sorts of formations — viz. the 

 plastidome, composed of plasts, or plastids ; and the chondriome, or vacuolar 

 system. The latter contains in solution a more or less thick substance 

 — the metachromatin ; both the chondriome and the contained meta- 

 chromatin are entirely independent of the plastidome, and differ from 

 the latter in becoming bright red when stained with Cresyl-blue. This 



ft 



* C.R. Soc. Biol. Paris, Ixxx. (1917) pp. 917-24 (2 pis.), 

 t Comptes Rendus, clxvi. (1918) pp. 439-46 (4 figs.). 



