360 PR. AV. I^yLAKBER ON TWO KEW CBITEIUA 



action of tlie hypoclilorite of lime; it exhibits only au elegaut zone 

 all round, and of the thickness of the cortical layer*. 



Let us now see, by the aid of the uew method, what, are the 

 reactions presented by the different f?pecies of SocceUei. 



1. We may first of all remark that those which are the richest 

 in colourable matter are the Comhea mollusca^ Soccella JMontagneiy 

 and _Z?. sinensis, 



2. Those Avhich are less rich in the colourable matter are the 

 Soccella tinctoria and H.pJii/copsis, which scarcely ditfer specifically, 

 and cannot always be distinguished from each other. Their young 

 thalli present the most beautiful reaction^ their older thalli being 

 very little coloured. JR-.fuciformis ordinarily exhibits the curious 

 peculiarity that its thallus is not coloured by the reaction, which 

 on the contrary gives to the soredia of this species the most vivid 

 red colour. It is a curious ihin^ that neither the soredia of 

 B. Montagnei nor oi B, pliycopsis exhibit any such reactionf- . 



In the B.fuciformis (fertile) collected in the Isle of Berleugas, 

 in Portugal, by Dr. Welwitsch, I have seen some reaction, espe- 

 cially at the extremities of the branches of the thallus. 



8. Xo reaction is visible \n, Boccella hjpomeclia (Ach.), B, Gcnj- 

 ana, and B. leucoplicea. 



Thus are we now able, with the aid of the hypochlorite of lime, 

 with great facility to separate and distinguish the species of this 

 diillcult genus, in which heretofore the determinations have been 

 often uncertain. This reactive manifests also this remarkable 

 fact, that determinations perfectly exact (" a Tetat actuel de la 

 science") may be made even on specimens which are in a young 

 and sterile state, and in other respects very incomplete. 



But it is not to the Bocellei alone that the application of this 

 practical mode of study is limited. I have in my writings noticed 

 the analogy existing between the Boccella^ and the Birince, the 

 latter appearing in reality to h^Boccellcje with a crustaceous thallus. 

 The hypochlorite of lime confirms this analogy. The Dirin^ 

 exhibit a very distinct erythrinic reaction. In TTrceolaria scru- 

 posa and its allies the reaction is produced immediately the thallus 

 is touched by the reactive. By these means we also learn that 



* At the same time I would remart that the medulla in R- Montagnei is 

 coloured blue by a solution of iodine. For this I use the following mixt\ire : 

 iodtne 1 grain, iodide of potassium 3 grains, and water \ ounce. 



t It is necessary here to guard against error, since that portion of the thallus 

 which surrounds the soredia, on being coloured by the reactive, will transmit 

 the red colour to the soredia, if too much of the Uquid reactive be used. 



