LIVERWORTS. 53 



the sporules within the spore-case. This consists of 

 a single fibre, or of two twisted spirally in different 

 directions, so as to cross each other, and contained 

 within a very delicate, transparent, perishable tube ; 

 they have a strong elastic force, and have been sup- 

 posed to be destined to aid in the dispersion of the 

 sporules — a most inadequate end for so curious and 

 unusual an apparatus. It is more probable that they 

 are destined to fulfil, in the economy of these plants, 

 some function of which we have no knowledge." The 

 elaters which occur in the Horsetails, or Eqidsetacece, 

 are of a different character to those found in the 

 liverworts, and should not be confounded with them. 

 In this case the elliptical spores are furnished with 

 four elastic filaments, attached about the middle of 

 one side, which are coiled once or twice round the 

 spore, before it is discharged from the capsule, in 

 the position where they were originally developed ; 

 but when the spore is discharged they uncoil with 

 elasticity, causing the spore to be jerked away. The 

 result of investigation appears to prove that the outer 

 coat of the spore splits by a spiral fissure, and, sepa- 

 rating in narrow ribbons from the inner coat, becomes 

 the elastic appendages to which the name of " elatcr " 

 has been applied. 



In the liverworts the elaters are more or less 

 elongated membranous tubes, which are closed at 

 the ends, and contained within them are one or more 

 clastic spiral fibres. These bodies occur mixed with 

 the spores within the capsules, and are sometimes 

 attached by one end to the valves of the capsule, 

 so that they not uncommonly remain behind after 



