4/8 



Mr. H. C. Sorby vn 



[June 19, 



The colouring-matters found in Actinice are very various, and it is only 

 particular species that contain those found in Algce. Lichens, as a whole, 

 are characterized by a number of what may be called accidental consti- 

 tuents — such, at least, as occur in one species and not in another closely 

 allied to it. Many of these are almost or quite colourless substances, 

 which easily give rise to colouring-matters when treated with various 

 reagents. This fact, combined with their partial distribution, is taken 

 advantage of in studying lichens as a means for distinguishing closely 

 connected species. Their more constant and apparently fundamental 

 colouring-matters correspond with those found in the higher classes of 

 plants, but differ considerably in relative proportion, the lichnoxanthines 

 usually being relatively more abundant. 



Relation of Fungi to other Plants. 



Fungi cannot be arranged in a direct order in any part of the series 

 shown in the Table given above. Their most common colouring-matters 

 exactly correspond with those found in the apothecia of lichens, and 

 their more accidental constituents are also quite analogous to those 

 occasionally found in the apothecia of particular lichens — for example 

 in those of Cladonia cownicojnoides. 



According to the principles adopted in this paper, fungi ought then to 

 be looked upon, not as fronds, but as the fructification of a low type of 

 plants ; and I think that the fact of the colouring-matters alone leading to 

 such a satisfactory conclusion, shows that they must have some important 

 physiological signification. 



Connexion between the Colouring-matters of Flowers and those in the Leaves. 



Since a comparison between the colouring-matters found in the petals 

 of flowers with those in the foliage has many points of interest in con- 

 nexion with the relationships of fungi, it seems best now to describe some 

 of the principal facts. The coloured substances in the petals are in many 

 cases exactly the same as those in the foliage from which chlorophyll has 

 disappeared ; so that the petals are often exactly like leaves which have 

 turned yellow or red in autumn, or the very yellow or red leaves 

 of early spring, but in other cases special coloured substances are 

 developed which do not occur in leaves. Many yellow flowers are 

 coloured by a very variable amount and variable mixture of lichno- 

 xanthine and the three kinds of xanthophyll, but orange-coloured flowers 

 sometimes contain in addition other substances analogous to peziza 

 xanthine and phycoxanthine. The colour of many crimson, pink, 

 and red flowers is due to the development of substances belonging to 

 the erythrophyll group, and not mifrequently to exactly the same kind 

 as that so often found in leaves. The number of different species is very 

 considerable, and it would make this paper far too long to describe them ; 

 and, besides this, it would be requisite to explain methods of study 



