26 



VETERINARY PATHOLOGY. 



A. Prophase. This is the preparatory stage. The nuclear 

 chromatin which, in the resting cell, is an irregularly arranged 

 net-work, becomes a continuous single thread, forming the so- 



FiK J — Division 



called spircm or loose skein. The chromatin thread divides into 

 a definite and even number of segments, (the number varving in 

 different animals, but always constant in the same species) 

 known as chromosomes. These chromosomes are equal in length 



Fig. 5. ^Division of cell. 



and are usually bent like the letter "u." The chromosomes are 

 radially assembled around the central point in the nucleus, thus 

 forming the monaster or single star. I'he nuclear membrane 

 becomes less and less distinct as the spirem is forming and fin- 

 ally disappears. As the nuclear changes are progressing, a 

 centrosome l)ecomes prominent either within the nucleus or in 

 the cell bodv just outside the nuclear membrane. The centro- 



