ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 239 



BOTANY. 



A. GENEBAIi, including the Anatomy and Physiolog-y 



of the Phanerogamia. 



a. Anatomy.* 



Q) Cell-structure and Protoplasm. 



Nuclear Origin of Protoplasm.t — M. C. Degagny discusses further 

 some points whicii were only briefly treated in his former communication 

 on this subject. The history of the cell-nucleus is by no means finished. 

 New facts are continually being added which at first appear contradictory 

 to those already known. Observers who have studied the cell-nucleus 

 have noticed the peculiar phenomena which accompany the different 

 movements and evolutions of the chromatic bodies. These movements 

 are in part the result of intermittent contractions and dilatations, of which 

 these bodies are the seat. From observing the nucleus of the mother- 

 cell of the embryo-sac of the fritillary, the author shows that there 

 exists an immediate antagonism between the freshly formed protoplasm 

 which condenses at the base of the nucleus and the chromatic bodies. 



The hyaloplasm is secreted in quantity by the hypertrophied nucleus 

 of the mother-cell of the sac ; but hyaloplasm is not only produced in 

 the nucleus, but is expelled by incompatibility with the chromatic 

 bodies. Among the processes which belong especially to matters derived 

 from nuclear activity is one by means of which these bodies are able to 

 take upon themselves well-determined geometrical forms. 



Intercellular Protoplasm.^ — M. 0. Sauvageau describes an instance 

 of this structure in the roots which proceed from the nodes of the stem 

 of Naias major and minor. These have a very small central vascular 

 cylinder and a large cortex ; the cortical parenchyme consists of several 

 rows of cells with intercellular passages, which increase in size from the 

 tip to the older part of the root ; in the adult region these become 

 aeriferous canals, with cuticular coatings.§ Towards the tip of the root 

 there is no intercellular protoplasm ; it begins to be observed, however, 

 in the aeriferous canals 1-2 cm. from the tip. 



The origin of this intercellular protoplasm is from hernioid pro- 

 tuberances which project from the adjacent cells into the canals ; some- 

 times a cell will put out protuberances into two contiguous canals. 

 They can become so large as to fill up the whole of the canal ; they 

 frequently contain starch-grains, and very rarely the cell-nucleus is to 

 be found in them. The protrusion may be either closed or ruptured at 

 the extremity. They are especially well shown on longitudinal section, 

 and are then seen usually to proceed from the lower extremity of a cell. 

 Their formation takes place at a very early period. 



C2) Other Cell-contents (including- Secretions). 



Hydrolencites and. Grains of Aleurone. jl — M. P. Van Tieghem calls 

 attention to the researches of Wakker and Went ^ by which the so-called 



* This subdivision contains (1) Cell-structure and Protoplasm; (2) Other Cell- 

 contents (including Secretions); (3) Structure of Tissues; and (4) Structure of 

 Organs. 



t Bull. See. Bot. France, xxxv. (1888) pp. 348-57. Cf. this Journal, 1888, p. 440. 



t Morot's Journ. de Bot., ii. (1888) pp. 396-403 (4 figs.). 



§ Cf. this Journal, 1886, p. 471. |1 Morot's Journ. de Bot., ii. (1888) pp. 429-32. 



i Cf. this Journal, 1888, pp. 443 and 981. 



