HARDWICKE'S SC I£N CK-G OSSIP. 



249 



two, and again soon returning to tlie top as if for 

 air. Tlie parents, on the contrary, seldom go to the 

 top of the water ; with them it is not a necessity. 

 During the day thirteen other young ones left the 

 pouch of the parent and issued forth into tlie world 

 on their own account. On the two subsequent days 

 other young ones followed the example .of the 

 thirteen, until the number amounted to about two 

 hundred, for it was impossible to ascertain the 

 exact number. 



The young of the Hippocampus are hatched in a 

 pouch, which is in all cases in the tail of the male 

 parent, the-ova being placed there by the female as 

 in a nest. It has been supposed that tiie young 

 occasionally return to the pouch for protection or 

 rest, but I have not been able to ascertain if that be 

 a fact or not. 



The young Hippocampi are about three-fourths of 

 an inch in length, and singularly exact in their like- 

 ness to their parents : the only noticeable difference 

 is that the eyes are unduly prominent ; in every 

 other respect, as also in their mode of swimming 

 and peculiarities of habit, they are the counterparts 

 of their seniors. Perhaps in these general remarks 

 I should refer to the greater activity of the' young, 

 and their frequent visits to the top of the Avater. 



Thomas Brittain. 



THE PORMATION OF CHLOHOPHYLL OR 

 LEAP-GREEN. 



a"lHE most superficial observer cannot fail to have 

 noticed, whilst passing through the cultivated 

 districts of this country, that the growing crop on 

 one part of a field is sometimes of a light green, 

 whilst that on another part of the same field, sown 

 at the same time, with the same seed, is of a much 

 darker colour. Those who more carefully examine 

 this phenomenon will discover that this dark green 

 is most frequently produced by a supply of nitrogen 

 to the roots of the plants, and will probably ask 

 themselves the question whether this colour is, as 

 Liebig asserts, an abnormal development of leaf to 

 the injury of the plants, or whether it indicates a 

 healthy, vigorous growth which would produce a 

 heavy crop? It is asserted by most farmers that "like 

 colour so crop," and in the published results of 

 experiments with manures by Messrs. Lawes & 

 Gilbert, of Rothamsted, the correctness of this theory 

 is clearly shown ; but as their writings are not 

 studied by many, I will give the result of a few 

 simple experiments which I have made, that I may 

 the more clearly prove this point. In the first of 

 these I grew barley plants in two saucers supplied 

 with ordinary well-water; to one of these I added a 

 few grains of nitrate of soda. This produced no 

 visible increase of colour in the plants to which it 

 was applied ; thus showing that the nitrogen con- 

 tained in nitrate of soda will not produce any more 



colour in the plants unless they are provided with 

 the other elements .which they require. In the 

 second experiment barley was grown in four pots 

 filled with almost pure sand, to the first of which 

 no manure was applied. To the second I added five 

 grains of nitrate of soda, which contains as much 

 nitrogen as the barley could require. In the third pot 

 I placed 10 grains of wood-ashes, which would sup- 

 ply all the inorganic substances necessary for the 

 ■plants. In the fourth I placed both the five grains 

 of nitrate of soda and 10 gains of ashes; thus pro- 

 viding the plants in this instance with all the requi- 

 sites to a healthy vigorous growth. When the barley 

 in this last pot had reached the height of 5 inches? 

 and those in pots 1, 2, and 3 were all about 3 inches 

 above the soil, they were destroyed by drought, but 

 a note taken before that time states that the colour 

 of the plants in pots 1, 2, 3 was nearly the same, 

 but those in pot i were much darker. In this ex- 

 periment, therefore, the richest green was obtained 

 in the pot which produced the greatest growth- 

 The third experiment was a repetition of the second, 

 —the same sand, manures, and seed being employed, 

 and in the same proportion as in the last experiment. 

 After a little more than a month's growth, the barley 

 in pots 1, 2, and 3 was about 3 inches in height, 

 and in each of an equally light green tint, while 

 that in pot 4 was 7 inches above the soil and a 

 dark luxuriant colour. It appears, therefore, that 

 the formation of Chlorophyll is in some way directly 

 connected with healthy growth, and is not produced 

 by nitrogen, unless there be a sufficient supply of 

 mineral matters to the roots. 



We also know that the green colour of plants 

 depends on light. This may be easily proved by 

 growing some mustard in two pots, one exposed 

 to light, the other placed in the dark ; and you will 

 find that those which have been grown in the dark 

 will be of a pale yellow, but those exposed to the 

 sun's influence of a dark green ; thus showing that 

 the effect of manures, in producing this colour, 

 either depends on, or influences, the action of light, 

 for without the solar rays the colour cannot be 

 formed. 



This naturally leads to the inquiry, what is the 

 chemical action of light? We know that the leaves 

 of plants absorb carbonic dioxide, which, under the 

 influence of light, especially dii-ect sun-light, is 

 deoxidized, and the carbon, combining with the sub- 

 stances absorbed by the roots, forms the organic 

 compounds of which the plant consists. This only 

 takes place in light : it therefore appears that light 

 exercises a deoxidizing influence. If this be true, it 

 ought to be prejudicial to all chemical actions in 

 which oxygen is absorbed, especially if the substance 

 undergoing oxidation be carbon or any carbonaceous 

 compound. 



The action which takes place in germinating seeds 

 is one of oxidation; the starch they contain combines 



