RADIA TE APPEARANCES IN CELL DIVISION 247 



whole to the same processes, which also produce a sun round 

 the vacuole of Amceia terricola. Since the last-mentioned 

 radiate appearance only exists during the growth of the 

 vacuole, i.e. while the vacuole is drawing in water from the 

 surrounding protoplasm, I concluded that the striation was 

 an optical expression of this process. I had thus arrived 

 at that time at an interpretation of the process, which was 

 confirmed fifteen years later by observations upon the 

 drops of oil-lather. Now since the radiate phenomena in cell 

 division completely correspond in appearance with the stria- 

 tion round the contractile vacuole, the conclusion seemed 

 obvious, that a corresponding migration of fluid and soluble 

 matter in the protoplasm was also the cause of the appear- 

 ances in the former case. Only at that time I thought it 

 necessary to assume that in this process a diffusion took 

 place in the reverse direction from the clear central area of 

 the suns into the protoplasm on all sides, from which of 

 course the appearance of striation would result in like manner. 

 This train of ideas was confirmed, as has been said, by the 

 observations upon oil -drops, for, as I explained before, 

 radiate appearances arise in them both when diffusion is 

 set up from the drops into the external medium, and when 

 it is caused in the reverse direction from the latter into 

 the drops. The striation therefore only presupposes the 

 existence of such a diffusion movement, it being a matter 

 of indifference whether it prevails in the one or the other 

 direction. 



In recent times our knowledge of the origin of the 

 radiate appearances in division has, as is well known, been 

 considerably extended. It has been shown that they are 

 not produced by the nucleus or the protoplasm itself, as I 

 assumed even in 1876, but they are in connection with 

 certain peculiar corpuscles, which are permanently present 

 near the nucleus in the protoplasm, the so-called centi-al 

 bodies. The protoplasmic rays are always formed round the 

 central 'bodies, whether they have already become noticeable 

 in the resting cell, or whether they only gradually develop 

 at the commencement of the division round the central 

 bodies. These facts only recently discovered necessitate of 



