1879.] THE GARDENER'S PRIMER. 425 



THE GARDENER'S PRIMER. 



NO. V. 



This power of decomposing carbon dioxide (carbonic acid), and of 

 decomposing ammonia into hydrogen and nitrogen, and water into 

 hydrogen and oxygen, and of recombining, solidifying, and utilising 

 these elements in their structure, is possessed by all plants containing 

 chlorophyll in their leaves and in the lower forms of plant-life, as 

 Paranerna in their free cells. The cells by which plants absorb oxygen 

 and disengage carbon dioxide are not cells containing chlorophyll. 



The results of the recent investigations of Mr H. C. Sorby of Shef- 

 field, tend to show that the colouring matter in the green leaves of 

 plants are not simple green-coloured granules, but mixtures of chloro- 

 phyll and other colouring substances in a free state, differing in plants, 

 and having different chemical reactions, requiring new names, as 

 chlorophyll, blue and yellow chlorophyll, xanthophyll, orange and 

 yellow xanthophyll, lichnoxanthine, and orange lichnoxanthine, &c. ; 

 and that the word endochrome would be a better word to use than 

 chlorophyll as a general term. Further researches in this branch of 

 science, called comparative vegetable chromatology, may tend to ex- 

 plain the causes of many of our beautiful autumnal tints, and of the 

 presence of the colouring substances in the petals of the corolla. 



It has been stated, generally, that plants with chlorophyll in their 

 leaves have the power of decomposing and recombining the elements 

 carbon, hydrogen, oxygen, and nitrogen into various states or com- 

 pounds, but it is not correct to suppose that they are all equally en- 

 dowed with the extraordinary powers of recombining and rearranging 

 some or other of these elements into all of the following compounds. 

 It will be easily seen, from the names of some of them in the third 

 division, that they are confined to certain plants, and not possessed 

 by other plants. The following are the compounds alluded to : 

 Firstly, compounds of the elements, carbon, hydrogen, and oxygen, 

 generally called ternary, sometimes carbonaceous compounds, or 

 carbo-hydrates, and to these elements the plant is indebted for its 

 cellulose (the basis of all vegetable tissue), starch, dextrine, sugar, and 

 fixed oils ; secondly, compounds of the elements, carbon, hydrogen, 

 oxygen, and nitrogen, generally called quaternary, sometimes nitro- 

 genous compounds, and to these elements the plant is indebted for 

 its albumen, fibrine, diastase, and caseine ; and thirdly, to all the four 

 elements above named the plant is indebted for its acids, such as 

 citric, acetic, tartaric, malic, tannic, hydrocyanic, oxalic, and gallic 

 acids ; and for its alkaloids, such as aconitine, atropine, quinine, mor- 

 phine, strychnine, theine, or caffeine j and for its volatile oils, resins 



2 G 



