62 BOTANY pakt i 



shaken iip with benzole, the latter, as Kraus first showed, on standing rises to tlie 

 surface as a green solution, leaving the alcohol yellow. 



According to recent researches (■*i) there are two components of the green 

 chlorophyll pigment ; these are the crystallising and the amorphous chlorophyll. 

 Both are comple.x compounds, containing no trace of iron, and they perhaps differ 

 somewliat in different plants. The yellow pigment in tlie chloropliyll grains 

 consists of carotin (which forms orange-red crystals, and appears to he a carbo- 

 hydrate) and of the amorphous xanthopliyll, which is most probably an oxide of 

 carotin. The alcoholic solution of chlorophyll is characterised by four absorption 

 bands in the less refrangible half of the spectrum, and three in the more refrangible 

 portion. The amount of chlorophyll in a green plant is very small. Tsciiirch (*^) 

 has calculated that only 0'2-l"0 gr. of cliloropliyll can be obtained from a 

 square metre of green foliage leaves. 



From the investigations of L. Makchlevvski, E. Schunck, and M. Nencki 

 it appears that a relationship exists between chlorophyll and hremoglobin (the 

 pigment contained in red blood corpuscles). 



The green colour of the chlorophyll in some groups of Algae is 

 more or less masked by other pigments. In addition to the chloro- 

 phyll green, with its accompanying yellow pigments, many of the 

 blue-green Schizophyceae contain a blue colouring matter, phycocyanin, 

 while the red Algae possess a red pigment termed phycoerythrin. 

 These pigments are soluble in water, and are characterised by a 

 beautiful fluorescence. The phycocyanin may often be found as a 

 blue border surrounding a blue-green Fission-Alga which has been 

 dried in a press. Whether these pigments are mixed Avith the 

 chlorophyll or are chemically combined with it is as yet unde- 

 cided (■*^). Recently Hans Molisch (■*•*) has attempted to prove 

 that the brown coloration of the Diatoms, the Brown Algae, and 

 especially of a saprophytic Orchid {Neoftia nidus avis), is not due to a 

 mixture of a brown pigment with chlorophyll. He regards it as due, 

 on the other hand, to a single pigment, phaeophyll, which is 

 nearly related to chlorophyll and readily undergoes a chemical 

 change into ordinary chlorophyll. 



Before the leaves of trees fall in the autumn, the chloroplasts 

 undergo disorganisation, and thus, according to Ern^t Stahl (^^), the 

 derivatives of the chlorophyll, and to some extent other useful sub- 

 stances, are transported to the stem. There remains only a watery 

 substance in the cell cavity, in Avhich a few oil globules and crystals, 

 togetlier with a few yellow, strongly refractive bodies, can be seen. 

 Sometimes in presence of abundant sugar this liquid in the cell 

 cavities becomes red, and thus imparts to the foliage its autumnal 

 brilliancy. In the leaves of coniferous trees, which only indicate 

 the approaching winter by assuming a somewhat brownish tint, the 

 cause is different. The chlorophyll-green of their chloroplasts changes 

 to a brownish green pigment, but in the following spring regains its 

 characteristic colour. 



In such phanerogamic parasites or hunnis-plants as are devoid of 



