HYPOTHESES OF MOLECULAR STRUCTURE 79 



the protoplasm are equally dependent upon the arrangement of its com- 

 ponent parts. 



It is at present uncertain whether the molecules of both organic. and 

 inorganic substances do not very commonly combine in aggregates which 

 may be termed micellae. Thus crystals, in which the component parts are 

 regularly and definitely arranged, are supposed by many authors, to be built 

 up of physical units or micellae, although others deny this 1 . The meshwork 

 arrangement postulated for colloid substances might be due, either to a union 

 of micellae, or of molecules to form the bars of the meshwork 2 . In the 

 latter case a piece of such a gelatinous colloid would form a single gigantic 

 micella, just as a large crystal forms a single homogeneous unit by the direct 

 union of the molecules composing it. There is no reason why such molecular 

 unions to form micellae might not be large enough to be visible. Thus the 

 units or crystalline needles of which sphaerocrystals are composed are of 

 measurable size, and yet unite to form a whole which is capable of imbibition. 



As the ultimate structural elements of which the protoplast is composed, 

 physiological units are necessarily postulated, and these may be either 

 formed of groups of molecules, i. e. micellae, or of groups of micellae. The 

 micellar hypothesis is especially applicable to the protoplast, and hence it is 

 difficult to see why Wiesner 3 regards the existence of physico-chemical units 

 or micellae as being incompatible with the existence of the physiological 

 units which build up the protoplast. The physiological units, micellae or 

 micellar complexes as the case may be, must unite to form the different 

 organs of which the protoplasm is built up, but this is no reason for 

 regarding the latter as a single micella, or as a micellar or molecular complex 

 of uniform character and forming a concrete whole, for the protoplast is 

 certainly a complicated piece of mechanism built up of a vast number of 

 different parts. 



From the above it is clear that we cannot assume that the products of 

 protoplasmic activity are necessarily built up of micellae, though this is 



1 Lehmann, Molecularphysik, 1889, Bd. n, pp. 376, 379, and the literature there cited ; Ostwald, 

 Lehrb. d. allgem. Chemie, 1891, 2. Aufl., Bd. I, pp. 376, 397; Groth, Die Molecular-Beschaffenheit 

 d. Krystalle, 1888. On the regular arrangement of minute crystals in fluids, see Lehrmann, Zeitschr. 

 f. physik. Chemie, 1890, Bd. V, p. 427. 



a See Sect. 12. Kekule (Die wiss. Ziele u. Leistungen d. Chemie, 1878, p. 22) assumes that 

 in colloids the meshwork is a molecular one. Strasburger (Bau u. Wachsthum d. Zellhaut, 1882, 

 p. 224) has attempted to prove that all organized bodies have a similar molecular structural arrange- 

 ment in the form of a molecular meshwork. From other points of view, however, which have been 

 overlooked by Strasburger, an assumption of the existence of physiological and hence also of physical 

 units is rendered necessary. As has already been mentioned (Sect. 12), the peculiarities observed in 

 the mode of swelling of given bodies may be produced by a linking together of either molecules or 

 micellae. See also Schwendener, Uber Quellung und Doppelbrechung, in Sitzungsb. d. Berliner 

 Akademie, 1887, Bd. xxxiv, p. 659. 



s Wiesner, Die Elementarstructur, 1892. Cf. Pfeffer, Studien z. Energetik, 1892, p. 157, and 

 Sect. 8 of this book. 



