FOUNDATIONS 13 



In mitosis spindles are formed by re-arrangement of 

 linin fibres. Spindles are usually formed inside, but some- 

 times outside the nuclear membrane. 



The substance that separates two nuclei after mitosis 

 comes from the linin spindle. 



In the following pages where my own observations are 

 referred to and it is not otherwise stated, cells, plasmodia, 

 or tissues were stained with acid haematoxylin after fixation 

 by Foa's solution: see note at the end of this book. With 

 this stain pure chromatin is of a deep blue colour. 



Ehrlich divided dyes into basic and acid according as 

 the colouring matter plays the part of an acid or a base 

 the compound employed (Wilson). Ehrlich's statement 

 only applies to cover-glass preparations dried and fixed by 

 heat without the use of reagents (Lee's " Microtomist's 

 Vade Mecum"). 



Heidenhain termed the chromatin of Flemming " basi- 

 chromatin " to distinguish it from nucleoli, cytoplasm, and 

 other parts of cells which take acid dyes, such as acid fuchsin 

 and eosin. He concluded that basichromatin is rich 

 in nucleic acid, which Bayliss defines as a compound of 

 phosphoric acid with a 5-carbon sugar and a purine derivative. 

 The staining reactions of nuclei of the same organism 

 may vary : thus Barrett found in the chytridian Olpidiopsis 

 Saprolegniae that after the gonoplasm has passed into the 

 oogonium the nuclei in the resulting oospore stained more 

 deeply with safranine than they did before fertilisation. 



