SlUinrES OF REPRODUCTIVE ELEMENTS: II. 



309 



spore-fon nation. During the whole process of the division of the 

 nucleus it remains always closely attached to the outside of the latter, 

 and in the dividing individual is still to be recognised just before 

 the separation of tlie individuals, as represented by Fig. 12, and even 

 for some time after the complete separation, as one of my ])repara- 

 tions of the animal twelve liours after lias shoTvn very plainly. 

 After the formation of tlie peristome, teeth, etc. it becomes indistinct. 

 In the spore-buds the archoplasm remains till the final stage when 

 the spore is ready to swim olf iVoni the body of the mother animal, 

 as Figs. '2o-'M), 19-51 show very plainly. In nearly ripe spores, 

 Figs. 27-30, the arclioplasm lies on that side of the Ixxly which 

 is attached to the mother cell, and is therefore at the liead end 

 •)f the spore when it detaches itself from the bod\^ of the mother. 

 This is more clearly to be seen from sections of nearly ripe spores, 

 represented by Figs. 2o-2G. I sought after this body in ripe spores 

 treated wnth acetic-acid -methyl -green, but could not get any satis- 

 lactory knowledge of its existence. From the position of the archo- 

 plasm, and from the manner of division in the foregoing stages, 

 it is clear tliat the free end of the spore corresponds to the equatorial 

 part of the archoplasmic spindle, while the end attached to the surface 

 of the mother animal is the pole of the spindle. 



'... 0. The cenfrosouie : — In many cases in the centre of the archo- 

 plasm is seen a small round body, which often colours very deeply 

 with aniline dyes, especially with such colouring matters as rubin, 

 iodine-green-methylen-blue, etc., but also with luvmatoxylin, when 

 this is used in C(jnjunction wûth iron ammonium alum, as given by 

 Heidenliciu (15, ]). 118-119). In a short note on the conjugation of 

 Xoctiluca (26, ]>. 3) I stated that at the poles of the two C(nijugat- 

 ing nuclei, deeply-staining round bodies are found, similar to those 

 seen in the centre of the archoplasm, and suggested that such bodies 



