1899] AS REGARDS PROTOPLASM 167 



cell it is in reality an alveolar structure — an emulsion — such as 

 Biitschli has described. The living stuff of an Echinoderm ovum is 

 in the form of a fine emulsion consisting of a continuous substance in 

 which are suspended drops of two orders of magnitude and of different 

 chemical nature, the larger drops determining the primary alveolar 

 structure as described by Biitschli, the smaller drops determining the 

 secondary or finer alveolar structure as described by Beinke. As to 

 the astral rays in the sea-urchin egg and elsewhere, they involve a 

 radial arrangement of the alveoli, but they involve more, namely, 

 definite flbrillae which grow by progressive differentiation out of the 

 general cytoplasmic meshwork. 



The phrasing of the last sentence suggests a more general con- 

 clusion — "that alveolar, granular, fibrillar, and reticular structures 

 are all of secondary origin and importance, and that the ultimate 

 background of protoplasmic activity is the sensibly homogeneous matrix 

 or continuous substance in which those structures appear." Not that 

 the author puts his finger upon this, so to speak, and says this is the 

 living matter, for " in its fullest meaning the word living implies the 

 existence of a group of co-operating factors more complex than those 

 manifested by any one substance or structural element in the cell, 

 nevertheless, we are perhaps justified in maintaining that the continuous 

 substance is the most constant and active element, and that which 

 forms the fundamental basis of the system, transforming itself into 

 granules, drops, fibrillae or networks in accordance with varying 

 physiological needs." Thus we are led to the conclusion that the 

 physical basis of life is in the invisible organisation of a substance 

 which seems to the eye homogeneous. Beyond this, as far as 

 morphological aspects are concerned, all is hypothesis, and the form 

 of hypothesis which Professor Wilson favours is "that the homogeneous 

 or continuous substance may be composed of ultra-microscopical bodies, 

 by the growth and differentiation of which the visible elements arise, 

 and which differ among themselves chemically and otherwise, as is the 

 case with the larger masses to which they give rise." 



The Darmstadt Museum. 



Although the new building of the Grossherzogliche Museum at 

 Darmstadt is unfinished and untenanted, the plan of the zoological 

 portion has been carefully worked out by Dr. G. von Koch, the director, 

 and some idea of its main features can be gained from his programme 

 and from the newer cases in the old museum. 



In the " Schausammlung " or show collection intended for general 

 instruction, there is of course a systematic series, but prominence is 

 given to cases showing things more or less as they are in nature or 



