288 PRACTICAL HISTOLOGY [XXXVI 



4. Sections of rootlets of Pinus. (Alcohol, or 

 mercuric chloride, frozen, cut longitudinally, stained 

 with hsematoxylin.) Note: 



The cell- spindles in various stages of development. 

 The chromosomes are generally bent at a right angle 

 near one end. 



The cell-plate, seen as a thin granular band 

 running across the middle of the cell-spindle in the 

 cells which are dividing. 



DEMONSTRATIONS. 



1. Section of salivary gland of larva of Chironomus 

 (Flemming's fluid; Ehrlich-Biondi stain). Note the 

 very large nucleus ; the long filament in it, consisting 

 of stained discs (chromatin) and of unstained substance 

 (hyaloplasm) ; the large nucleolus. 



2. Embryo-sac of Fritillaria imperialis (Hermann's 

 fluid; hsematoxylin). Note the different stages of 

 nuclear-division in the cell. 



NOTES. 



The larvae of salamanders, newts, or frogs may be taken for 

 cell-division. The larvae of the salamander may be cut out in 

 the spring, or taken soon after birth. The animals should be 

 well fed for some tune before death, the adult salamanders on 

 worms, their larvae on Tubifex riv. 



When hardened, the body of the larva is cut into pieces, 

 imbedded in paraffin and cut transversely. The tail is cut flat, 

 either imbedded or frozen. 



