74 HINTS TO MICROSCOPISTS. 



most gentle manner, as, for instance, in cutting off a specimen, or 

 causing it to descend in order to keep the summit of the plant below 

 the surface of the water. 



Secondly. Imitate the freshness of the water, by having an extent of 

 surface, which it is requisite to skim frequently, or suffer it to overflow 

 by the addition of more water. These precautions being attended to, 

 a clear bright surface is kept. It is also desireable to change a small 

 portion of the water ; but this should be done without agitation. The 

 best vessels for cultivating this plant in, are either wide pans, holding 

 three or four gallons, or glass jars a foot or more high ; into these the 

 Chara may be placed, either with clean water alone, or a little earth 

 may be sprinkled over it, so as to keep it at the bottom, or the bottom 

 may be covered one inch with closely pressed mould, in order that the 

 water may be put in without disturbing it. On this lay the Chara, 

 with a little earth over the lower ends, to fix it. By causing the water 

 to overflow is the readiest way to skim the surface, though dipping out 

 gently will do ; but in all cases of pouring in water, hold something, 

 such as a saucer or flat piece of wood, to receive the pouring, and make 

 it spread instead of allowing it to descend at once on the surface. Pans 

 in the open air, nearly full of water, will be kept in order by the wind 

 and rain, only taking care to supply the deficiency, (the effect of eva- 

 poration) and to change some of the water, if it be considered neces- 

 sary. The vessels kept in-doors have a film which is always forming 

 on the water, and which requires to be frequently removed. 



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 live 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 Valisneria, 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 handful 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, 



