275 



STRASBURGER'S NEW INVESTIGATIONS ON THE 

 PROCESS OF FERTILISATION IN 

 PHANEROGAMS. 



By THOMAS HICK, B.A., B.Sc, 

 President of the Botanical Section of the Yorkshire Naturalists Union. 



(Continued from page 205.) 



From all that has preceded, it may be gathered that Strasburger 

 considers it to have been demonstrated that fertilisation depends 

 upon the cell-nuclei, and upon the nuclei alone. The morphology 

 of the nucleus thus becomes an important subject of enquiry, and one 

 on which our author therefore dwells at considerable length. It is 

 shown that every cell-nucleus contains a much -convoluted anasto- 

 mosing nuclear thread, which forms the intra-nuclear network. This 

 consists of a ground substance of nucleo-hyaloplasma, the idioplasma 

 of Nageh, in which are embedded the nucleo-microsomes or granules. 

 Between the meshes of the network lie one or more nucleoli, and the 

 whole is contained within the nuclear cavity, which is filled with 

 nuclear sap, and is bounded by the nuclear wall. There is likewise 

 a network in the surrounding cytoplasma, but this does not project 

 into the network of the nucleus. The inter-action between the cyto- 

 plasma and the nucleus, when the latter is in the resting condition, is 

 simply dynamical, and although the cytoplasma has the same compo- 

 sition as the nucleo-plasma, there are important morphological and 

 physiological differences between them. The network of the nucleus 

 appears to have a permanent form, while that of the cytoplasma is 

 continually undergoing change. The nucleus seems to be charged 

 with carrying over from one generation to another the hereditary 

 characters of the species, and to this is probably due its firmer struc- 

 ture and its complicated mode of division. The nucleus thus repre- 

 sents the fixed conservative principle of the organism, while the 

 plasticity of the cytoplasma enables it to adapt itself to the changing 

 influences of the environment. Moreover, the nucleus dominates the 

 metabolic processes going on within the cell, and determines the course 

 of development which ultimately produces the features which fix its 

 specific rank. On the other hand, the cytoplasma reacts on the nucleus, 

 excites it to divide, and, after every division, supphes the daughter 

 nuclei with the food stuffs necessary for their increase of mass. 



While the specific characters of a plant are thus due to the nuclei 

 of its cells, the individually-acquired peculiarities remain bound up in 

 the cyto-idioplasma. Strasburger agrees with Weismann, Nageli, 

 and others in thinking that too much importance has been laid upon 



July 1885. 



