H YD 



318 



H YD 



closed over in the space of four hours j it with water every evening, after they 



after impregnation. 



have got fairly into leaf. Towards au- 



10. When double flowers are desired, i tumn withhold watering; altogether. Get 

 if a double flower should chance to have their wood ripe. For winter, stuff" straw 

 a fertile anther or two, these should be between their branches, wrap them well 

 employed for fertilization, as their ofi"- in it, and mat them up." — Card. Chron. 

 spring are almost sure to be very double.! Hydrangeas are best preserved 



11. Many analyses of the pollen of through the winter out of doors, by 

 various plants have been made by che- taking off" their leaves in autumn, and 

 mists, without throwing any light upon putting over each one of the Shelters 

 hybridizing. M. Grotthus found the made of straw, as described under that 

 components of twenty-six grains of the j title 



pollen of the tulip were — 

 Vegetable albumen . . . 

 Malates of lime and magnesia 



Malic acid 1.00 



Malate of ammonia, colouring) 

 matter, nitrate of potash J 



HYDRASTIS canadensis. Hardy 

 20.25 '. tuber. Tubers. Loam and peat, in a 

 3.50 moist place. 



HYDRAULIC RAM. This is a use- 



- ful machine, the principle of which is 



but partially understood and valued. 



1.25 



12. Superfcetation has been doubted ; To bring the hydraulic ram into opera- 

 but as it occurs in the dog, we see no tion, it is necessary that there should be 

 reason for disbelieving its possibility in ' a head or body of water, as a pond, sup- 

 plants. Capt. Thurtell thinks it may be plied by a running stream, from which 

 done by the bee introducing mingled ' a fall can be obtained. The ram is an 

 pollens at the same instant. Then why i hydraulic machine composed of a body 

 not if a similar mixture is inserted by 1 at the end of which is a valve called a 

 the camel's-hair pencil of the culti- i pulse-valve, which is closed by the mo- 

 vator? ' mentum of a running stream of water. 



13. Plants nearly related, that is, j On the top of the body is an air-vessel, 

 closely similar in the structure of their in the neck of which is another valve 

 various parts, are those only which will | which admits the water into the air- 

 immediately impregnate each other ; , vessel upon the closing of the pulse- 

 but it is impossible, at present, to say : valve. The water meeting with an ob- 

 ■what families of plants may or may not j struction in the closing of the pulse- 

 be brought into fertile union through [ valve, immediately makes its way 

 intermediate crosses. A very short j through the valve into the air-vessel, 

 time ago, the azalea and rhododendron 1 The air in the air-vessel becoming 

 ■were thought incapable of such union ; j compressed, the valve leading into it 

 but this opinion is now exploded, forecloses, and thus liberates the pulse- 

 rhododendron ponticum has been fertil- I valve. The same action takes place 

 ized with the pollen of azalea sinensis, , again with the pulse-valve, and also 

 and the progeny between that evergreen , with the valve that leads to the air-ves- 

 and this deciduous shrub, is the pre- ; sel this continuous action takes place; 

 ■viously unknown phenomenon, a yellow , and at each time a portion of water is 

 rhododendron. Though such unions ' forced into the air-vessel. When the 

 may be effected, I entirely agree with air in the vessel is compressed so as to 

 Mr. Knight in anticipating that the pro- ' overcome the resistance in the pipe 

 geny will be mules, incapable of pro- i leading to the cistern, which it is in 

 ducing off"spring. 



HYDRAiNGEA. 



Six species. Hardy 



tended to supply, the water flows over, 

 and continues to do so, as long as the 



deciduous shrubs. Ripe Cuttings. Com- j ram remains in action 



irion soil. The species most common 

 in our gardens is H. hortensis. To ob 



There is also a small valve in the 

 neck of the air-vessel, introduced by 



tain of this very large flowers on a very Mongolfier's son, to supply the vessel 

 small stem, strike cuttings ; do not let with fresh air. Persons acquainted with 

 them branch: grow them in rich soil, hydraulics are aware that a column of 



and bloom them the following season. 

 To get large bushes of hydrangeas 



water is equal to its base ; that is to say, 

 pipe resting on a base four inches 



in the open air, plant them in good rich ' square is equal to sixteen times, though 

 soil; form a basin of clay all round them, I it rested on an inch square. This is 

 six inches deep, and in dry weather fill , the principle of the ram, as the falling 



