HISTOLOGY. 29 



cell is the power to reproduce a like cell. This is ac- 

 complished in two general modes : Direct and Indirect. 

 The Direct is observed in the protococcus and yeast 

 plants. The Indirect is studied in the higher animals. 

 For convenience the stages of changes are noted sepa- 

 rately. They are as follows : ( I ) Resting nucleus ; 

 (2) the Skein; (3) the Rosette; (4) the Aster; (5) 

 the Diaster; (6) the Daughter Rosette; (7) the' 

 Daughter Skeins; (8) the Daughter Nuclei. Each 

 one of these will be observed in the experiment with 

 the growing tip of the onion. 



Exercise No. 16. 



1. Grow some onions in a glass jar in some water. 



2. Cut off some of the tips of the growing rootlets. 



3. Fix them in formalin solution. 



4. Harden in alcohol for I hour. 



5. Dehydrate with absolute alcohol. 



6. Place the tissue in equal parts of ether and abso- 

 lute alcohol for twelve hours ; then place it in thin eel- 

 loidin for twelve hours. 



7. Now place it in thick celloidin for twelve hours. 



8. Embed, section, mount and stain. 



9. Examine with H. P. and the oil immersion. 



Technic for making the solution. The formalin is 

 made as follows ; 



