104 



Spring, whose waters, almost turbid with some ferruginous 

 matter, redden the stones they run over, and will throw 

 down clouds of solid matter by standing in a bottle for a 

 few days. This is a true chalybeate water, and may acquire 

 its properties by the decomposition of iron pyrites. 



The Chair observed that from the rocks we may readily 

 turn our attention to the vegetation that covers and adorns 

 them. Many fine species may be detected in this region ; 

 some of them have come to our notice to-day. The fragrant 

 White Alder, (Clethra), the Dogbane, (^Apocynmn), and 

 the various Milkweeds, (Asclepias'), are all plants of beauty 

 and deep interest. A species of the latter, the Common 

 Milkweed (^4. Cornuti) has a fibre of great strength and 

 delicacy, resembling that of Flax. A lady of Salem made 

 extensive experiments on this material a few years since, 

 and succeeded in manufacturing it into various textile fab- 

 rics of much excellence. In approaching damp lands, or, as 

 here to-day, large ponds, we find the vegetation always more 

 or less modified, and new forms appearing. Such plants as 

 the Monkey Flower, (^Mimulus) and the various species of 

 Orchis were then usually met with, as we have found to-day. 



CM. Tracy said that the Orchis Family, alluded to by 

 the Chair, is a very remarkable one, as well as very exten- 

 si've. Among its multitudinous species, two entirely diverse 

 modes of growth are observed. The European and North 

 American forms follow the usual style, and sustain them- 

 selves in the soil by means of ordinary roots. Some ot the 

 tropical kinds do the same ; but very many are without 

 roots, or have them transformed into organs lor holding, by 

 which they attach themselves to rocks, trees, &c., and these 

 grow with no connection whatever with the earth. They 

 are not mere exceptions, but form a great division of the 

 family, which is thus distinguished into Terrestial and Epi- 

 phytic species. The Lobelias are all plants of much interest 



