214 SUMMARY OF CURRENT RESEARCHES RELATING TO 



gen. et sp., with a spherical body, prolonged into a curved beak, 

 giving origin to one long cilium. lu the dead cells of Pylaicella and 

 other Phaeosporous Algte there was found a colourless form of a 

 Labyrinthula which had previously been found thriving in the cells 

 of a Lemna. Finally, a new Moner, Gobiella borealis, which shows a 

 great resemblance to Vampyrella, but the green contents seem never 

 to extend into the pseudopodia. 



BOTANY. 



A. GENERAL, including- Embryology and Histology of the 

 Phanerogamia. 



Free Cell-formation in the Embryo-sac of Angiosperms.* — Dr. 

 F. Soltwedel thus sums up the results of a series of observations on 

 this subject on various plants : — 



The mode in which the mature nucleus is developed from the 

 homogeneous lump of nuclear substance may be regarded as a forma- 

 tion of vacuoles within it. The contents of the vacuoles constitute 

 the nuclear sap, the nucleoli and the nuclear network and external 

 layer proceeding from the substance of the nucleus. Since in many 

 mature nuclei no external substance is to be recognized, and the 

 nuclear sap is in these cases always sharply diflferentiated from the 

 surrounding protoplasm, it may be assumed that the nucleus is sur- 

 rounded by a nuclear membrane, which may be formed by a chemical 

 action either of the nuclear substance or sap upon the surrounding 

 proto^jlasm. 



When the nucleus multiplies, the nuclear substance alone divides, 

 and forms first of all the primary spindle. At this stage the nuclear 

 sap penetrates into the surrounding protoplasm, the nuclear membrane 

 being always absorbed or ruptured. The protoplasm, which now 

 advances to the rods of the primary spindle, surrounds them with a 

 denser layer, and forms in this way the spindle-fibres. These are 

 visible at the poles when the nuclear substance is pressed to the 

 equator. After the halves of the nuclear plates separate, the spindle- 

 fibres remain between them as empty sacs. 



Coalescence of the nuclei is effected by the disappearance of the 

 nuclear membranes at the point of contact of the nuclei, and the union 

 of the corresponding constituents. Before the nuclei break up they 

 attain a very considerable size ; their membranes are finally absorbed, 

 the nuclear sap mingles with the surrounding protoplasm, and the 

 nuclear substance breaks up, with the formation of vacuoles in the 

 interior, into small pieces, which afterwards deliquesce in the proto- 

 plasm. The nuclear membranes are made up of small granules, the 

 composition of which could not be detected. 



Structure and Division of the Vegetable Cell.f — In a paper on 

 this subject Mr. J. M. Macfarlane, Demonstrator of Botany in the 

 University of Edinburgh, says that on examining the epidermal 



* Jenaische Zeitschr. f. Natiiiwiss., xv. (1881) pp. 341-80 (8 pis.). 

 t Traus. Bot. Soc. Edinb , xiv. (1881) pp. 192-219 (2 pis.). 



