ON LICHEtfS COLLECTED IN BODBIGUEZ. 431 



+ 



prepared in the ordinary way from pitchers gathered at the same 

 time from the same plants ; and in every case I found that the 

 digestive power of the former was much greater than that of the 

 latter. For instance, I placed a pellet of swollen-up fibrin in a tube 



containing a small quantity of the acid extract, and a similar 

 pellet in a tube containing the same quantity of the neutral ex- 

 tract. To each I added 2 cubic centims. dilute hydrochloric acid 

 ('2 per cent.), and exposed them both to a temperature of 40° C. 

 At the end of six hours the fibrin in the former tube had under- 

 gone complete solution, whereas that in the latter had been but 

 slightly attacked. The filtrates of both tubes gave the peptone 

 reaction. 



These experiments seem to indicate that in the gland-cells of 

 the Nepenthes pitchers, as in the^secreting cells of the stomach 

 and of the pancreas, the digestive ferment exists at first in com- 

 bination with some other body, as zymogen — and that in plants, 

 as in animals, this zymogen can be split up by the action of dilute 

 acid, the free ferment making its appearance as a result of this 

 decomposition. In fact, the experiments run perfectly parallel 

 with those of Ebstein and Grriitzner on the stomach, and with 

 those of Heidenhain on the pancreas, and afford a distinct con- 

 firmation of the views of the latter observer. 



Lichenes InsulaB Rodriguesii. — An Enumeration of the Lichens 

 collected by Dr. J. B. Balfour in the Island of Rodriguez 

 during the Venus-Transit Expedition, 1874. By the Rev. J. 



M. Ceomb^Ie, E.L.S. 



[Head June 15, 1876.] 



The present collection of lichens, made at intervals from Septem- 

 ber to December 1874, during the stay of the Venus-Transit 

 Expedition in the Island of Eodriguez, may be regarded as a very 

 fair representation of its lichen-flora. This is a matter which it 

 is always very satisfactory and, in a phytogeographical point of 

 view, most useful to know with respect to the plants collected in 

 any region, whether of limited or larger extent. In the present 

 case, as Dr. Balfour informs me, though some of the specimens 

 were picked up at random, yet special search was for the most 

 part made for lichens. Hence it may be inferred that, with the 



