DARWIN, NAEGELI AND DE VRIES 123 



theory of pangenesis. None of them, however, can 

 rival it in importance. 



In the opinion of other thinkers (Naegeli, Koelli- 

 ker, De Vries, O. Hertwig, etc.) , the particles do not 

 represent organic cells but the very properties of the 

 organism; in the opinion of others, like Weismann, 

 they represent both the cells of the organism and its 

 properties. Among the former, Naegeli and De 

 Vries deserve special attention ; Naegeli's theory is the 

 most important and the most inclusive of all and De 

 Vries' theory has introduced many new elements into 

 the discussion and attracted much attention in the last 

 few years owing to its new hypothesis as to the origin 

 of species. 



Naegeli's theory, formulated in 1884, preceded De 

 Vries' theory by a few years. 



The elementary particles which Naegeli designates 

 as micellae are, so to speak, organic crystals suspended 

 in an aqueous liquid and separated from each other 

 by thin envelopes of water, water being an integral 

 part of the protoplasm, as in crystallisation it is an 

 integral part of the crystal. Leaving aside all de- 

 tails of the micellae's precipitation and multiplication, 

 the essentials of the theory can be summed up as fol- 

 lows: The micellae are at first without any special 

 orientation. Owing to the action of their molecular 

 forces, some of them group themselves with a parallel 

 orientation, while the others remain unorientated. 



