THE CENTROSOME 



357 



also be concerned in the protoplasmic contraction of gland-cells by 

 which the excretion is expelled. [This is based on the fact that 

 the centrosomes are found in the free (pseudopodia-forming) ends of 

 the epitheUal cells, and on the position of the centrosomes in goblet- 

 cells (Fig. 23) and in those of the lachrymal gland.] Peter ('99) has 

 attempted to test these conclusions experimentally by cuttino- or tear- 

 ing off cilia from the cell-body (gut-epitheUum of Aiiodonta) and also 

 by isolating the tails of spermatozoa. In groups consisting of only a 

 few cilia, separated from the nucleus, the movements actively con- 

 tinue, while those that are separated from the basal bodies cease to 

 beat. Spermatozoon tails separated from the head also continue to 



Fig. 167. — Centrosomes and cilia in spermatocytes of a butterfly. [Henneguy.] 



move, but only if they remain connected with the middle-piece. 

 Peter, therefore, supports the above conclusions of Henneguy and 

 Lenhossek. On the other hand, Meves ('99) finds that movements 

 of the undulating membrane in the tails of salamander-spermatozoa 

 continue if the middle-piece be entirely removed; while a number 

 of earher observers^ have observed in flagellates that a flagellum 

 separated from the body may actively continue its movements for a 

 considerable time. 



Further research is therefore required to test these suggestions. 

 The intimate connection of the centrosomes with the formation, on the 

 one hand, of the astral rays, on the other of contractile organs, such 



1 See Klebs, '83, Biitschli, '85, Fischer, '94, 2. 



