CHAPTEE IIL 



PROTOPLASM PROTOPLASMIC MOVEMENTS THE NUCLEUS- 

 DRAWING WITH THE CAMERA LUCIDA, ETC. HOW TO 

 CALCULATE MAGNIFICATION PLASMOLYSIS. 



PRINCIPAL MATERIALS USED. 



Fresh flowers of Tradescantia (best T. virginica), just opened. Or T. zebrina. 

 Or, very young shoots of Cucurbita (Gourd, Pumpkin, Vegetable Marrow, 



Cucumber, etc.). Or, just opened flowers of Lamium sp. 

 Young fresh roots of Hydrocharis (Frogbit). Or, of Trianea bogotensis. 

 Fresh leaves of Vallisneria spiralis ; or, shoots of Elodea. 

 Fresh young parts of Nitella^ The same laid for twenty-four hours in 



1 per cent, chromic acid. 



PRINCIPAL REAGENTS USED. 

 Potassium nttrate, 10 per cent. Eosin in water. 



Protoplasmic Circulation. We will now study the phenomena 

 of the movement of living protoplasm, 1 and select as one of 

 the most favourable objects for this purpose the hairs on the 

 staminal filaments of Tradescantia (the Spider- worts). Trades- 

 cantia virginica, and other closely allied species, are cultivated 

 in every botanical and many ordinary gardens, and flower from 

 May or June till late into autumn. The long violet hairs in the 

 flower will at once catch the eye. For observation, select hairs 

 out of a flower which is either on the point of opening or has but 

 just opened. The preparation is made by seizing a tuft of hairs 

 at the base with the forceps ; remove them and lay them in 

 water. Or the whole filament can be placed under a cover-glass 



1 For the study of living cells water may sometimes be used as a mounting 

 medium, as in the cases in this chapter ; it generally, however, causes patho- 

 logical changes, and various fluids have therefore been recommended for use. 

 A weak solution (1-0 or 2*0 per cent.) of any neutral salt, e.g., saltpetre (potas- 

 sium nitrate) may be used, or a dilute solution of sugar (2'0 to 5 - per cent.), 

 or of gum-arabic. [ED. 



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