ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 181 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including' Cell-Contents. 



Cytology of the Cyanophycese. — A. Guilliermond * has investigated 

 the Cyanophyceffi with reference to (1) the cortical layer, (2) the 

 central body, (3) the origin of the metachromatic corpuscles. The 

 author regards the cortical layer as the cytoplasm, holding in solution a 

 blue pigment, but he disagrees with Fischer in regarding the colouring 

 matter as of the nature of a chromatophore. The central body may be 

 regarded as a true chromatic network, or, in other words, as a nucleus 

 without a membrane. The metachromatic bodies have the same charac- 

 ters as those of the Fungi, and their origin is clearly nuclear. 



N. L. Gardner! has investigated the Cyanophycete with special 

 reference to the nucleus. The investigation shows the presence of a 

 series of nuclear structures, varying from a very simple form of nucleus, 

 which is scarcely delimited from the surrounding cytoplasm, to a highly 

 differentiated distinct nucleus. The simplest nuclear structures divide 

 amitotically, but the higher forms show a primitive form of mitosis, and 

 in structure resemble the nucleus of the Chlorophycese. Under slow 

 desiccation, the nucleus may assume a resting condition. Definitely 

 organised chromatophores are absent, and there is no evidence of con- 

 tinuity between the vegetative cells. Change in habitat does not 

 produce change in cytological characters. 



Epidermis of Terrestrial Plants.^ — L. Geneau de Lamarliere, con- 

 tinuing his investigations upon the epidermis, now describes his results 

 with terrestrial plants. He divides the latter into two classes ; the first 

 includes such plants as Gheiranthus Gheiri, Brassica oleracea, etc., and 

 here the epidermis bears a close resemblance to that of aquatics, both in 

 structure and chemical composition. The second class, which is con- 

 nected with the first by many intermediate forms, includes such plants 

 as Ruta graveolens, Euonymus japonka, Bupleurum friiticosum, etc. ; 

 here, cutinisation extends almost to the external membrane, but the 

 colour reactions of the pectic and accompanying compounds are masked, 

 except in contact with the innermost membrane. The epicuticle can be 

 distinguished, and has the same constitution as in the preceding groups. 



• * Rev. G6n. Bot., xviii. (1906) pp. 447-65 (2 pis. 1 fig.), 

 t Univ. of California Publications (Botany), ii. (1906) pp. 237-96 (pis. 21-6). 

 X Rev. Gen. Bot., xviii. (1906) pp. 372-8. 



