NUCLEUS 



membrane, and is made up of two parts of different chemical and physical 

 characters, a formed substance with great affinity for certain dyes, and hence called 

 chromatin, and a structureless more fluid substance, the achromatin or karyoplasm. 

 The chromatin is generally in the form of a network, with thickenings at the nodal 

 points ; but often the nodes are the more prominent feature, and the network 



1 8 



FIGS. 8 TO 8. KARYOKINESIS IN BED BLOOD-CORPUSCLES OP LARVAL LEPIDOSIREN. (T. H. Bryce.) 



forms only a mesh of fine threads between them. The thickenings are named 

 karyosomes. The chromatin, which generally takes the form of solid filaments, but 

 frequently also is seen in the form of granules in a non-staining basis (linin), has a 

 special affinity for basic dyes, and is hence called basichromatin ; but there are also 

 granules in the filaments composed of a material which stains with acid dyes, hence 



B 2 



