LOGETIC CHARACTER OF GROWTH 55 



different differentiations may result by only changing their posi- 

 tion with regard to their environment has been shown by Mor- 

 gan by his experiments on the development of frogs' eggs. 



It seems probable to me that these different influences operate 

 upon the centrosomes and by means of the centrosomes on the 

 rest of the cell and the nucleus. It seems probable also that in 

 this way each centrosome introduces different somatic properties 

 into the plasm of the daughter cells, so that by means of the 

 centrosomes not only an increase of the cells is effected, but also 

 an adequate organoplasty differentiation. 



In this connection it seems to me of great importance to inquire 

 whether in malignant new growths where the adequate organoplastic 

 formation of cells is absent the centrosome has undergone a change. 

 The fact that the centrosome, or the substance from which it is derived, 

 is very sensitive to external influences makes it easy to believe that the 

 centrosome can become ill under the influence of inadequate processes 

 and this illness of the centrosome might include the failure of organo- 

 plastic development. 



My opinion about the centrosome as an intermediary of extra- 

 cellular influences seems to be confirmed by the relation of the 

 centrosomes in sense-cells, where they are always found in that 

 part of the cell that is turned to the external side which receives 

 the influence. 



In the larval retina they are found (Furst) as real centrosomes 

 in the receptive part of the neuro-epithelium. In the adult rods 

 and cones they are found in the 'Aussenglied' (Kolmer), while in 

 the olfactory cells, auditory cells (Held), and cells of the saccus 

 vasculosus (Dammerman) they are attached (eventually as 

 diplosomes) to the hairs which project into the surroundings 

 (fig. 1). This clearly demonstrates that the centrosomes have to 

 do with external influences. 



The same is seen in nerve-cells. In the embryonic nerve-cell, 

 the neuroblast, the centrosome generally lies near the pole where 

 the first offshoot of the nerve-cell, the axis cylinder arises (Held). 

 The position of the fibrillogenetic zone, so says Held, always coin- 

 cides with the position of the centrosome. 



