382 MANIPULATION. 



" Thirdly. Imitate the equal temperature of its native 

 holes, by sinking the pan a little within the earth, but, during 

 frosty weather, keep the pan in-doors, and at the lower part of 

 the house, as this situation is generally the most uniform in its 

 temperature. 



" The Chara will hve in any temperature above freezing, 

 and grows quicker as the warmth increases, but above the 

 earth, as outside of a first-floor window, it will not bear the 

 daily difference between the mid-day sun and the cold of sun- 

 rising. 



" The glass jars I keep within the house, as nearly uniform 

 in warmth as convenient. 



" Similar care is requisite for Vallisneria, but the warmest 

 and most equal temperature is better suited to this plant. It 

 should be planted in the middle of the jar, in about two inches 

 deep of mould, which has been closely pressed ; over this, 

 place two or three handsful of leaves, then gently fill the jar 

 with water. When the water requires to be changed, a small 

 portion is sufficient to change at a time. It appears to thrive 

 in proportion to the frequency of the changing of the water, 

 taking care that the water added rather increases the tempe- 

 rature than lowers it. 



" The natural habitat of the Frog-bit is on the surface of 

 ponds and ditches ; in the autumn its seeds fall, and become 

 buried in the mud at the bottom during the winter; in the 

 spring these plants rise to the surface, produce flowers, and 

 grow to their fuU size during summer. In order to keep 

 them for microscopic purposes, large pans, with earth at the 

 bottom, wiU preserve them through the winter, and if left 

 out of doors during the cold months, the pans should be sunk 

 into the ground to preserve the buds from the extreme cold." 



The author has found the following a very convenient way 

 of changing the water in the Chara and Vallisneria jars, viz., 

 to place the jar occasionally under the tap of a water tank, and 

 allow a very gentle stream to flow into it for several hours ; 

 by this means, all the impure water and conferva growing 

 on the sides of the vessel may be got rid of. 



Habitat— In the neighbourhood of London, the Chara 



