EQUISETACEiE. 



311 



microscope, a number of curious little chains, looking 

 something like the spring of a watch, will be found 

 among it, their use being to scatter the seeds ; and if the 

 seed-vessel be examined while in 

 the act of bursting, these little 

 springs will be found twisting 

 and writhing about like a nest 

 of serpents. The undulating 

 Hair-moss (Polytrichum undu- 

 latum), fig. 167, is found on 

 moist shady banks, and in 

 woods and thickets. The seed- 

 vessel has a curious shaggy cap ; 

 -feut in its construction it is very 

 similar to that of the Screw- 

 moss, except that the fringe 

 around its opening is not twisted. 



Equisetacece. — The history of 

 the development of the Ecpaise- 

 taceas (horse-tails) corresponds in 

 some respects with that of Ferns. 

 The spore-case of this solitary 

 genus is a most interesting object 

 under the microscope ; they have 

 apparently only one coat, for the 

 outer coat splits up into four 

 thread-like processes (elaters), 

 clubbed at tbeir free ends. 

 While the spore remains on the 

 sporange, these fibres are rolled round the spore, as seen, 

 in fig. 170, g; but by gently shaking the fruit spike, the 

 spores are discharged, the coiled fibres immediately unroll, 

 as at f, their elasticity causing them to spring about in a 

 most curious manner. In a few minutes this motion appa- 

 rently ceases, but if breathed upon they again unroll and 

 dart about with wonderful elasticity. 



Ferns. — In the Ferns we have an intermediate state, 

 somewhat between mosses and flowering plants ; this 

 would not apply to the reproductive apparatus, which is 

 formed upon the same type as that of Mosses ; and, 

 furthermore, it is to be observed, that Ferns do not form 



Fig. 167. — Hair-Moss in Fruit. 



