Mr. Henderson on the Reproductive Organs o/'Equisetum. 569 



abundance of minute granules. If detached by means of water during the 

 globular state, the integument has a flattened appearance (Tab. XXXIX. 

 fig. 6.), probably owing to the inability of the membrane to preserve its proper 

 form. At Tab. XXXIX. fig. 7- is represented the spore with its membranous 

 integument when it has attained sufficient consistency to preserve the oval 

 form ; it has at each end an appendage of apparently more delicate mem- 

 brane, the remains probably of what in an earlier state served to connect the 

 contiguous cells. This connecting membrane — if such it be — is the only trace 

 of any connexion between one cell or integument and another ; it is very soon 

 destroyed, and no mark of it remains in a more advanced state of the integu- 

 ment. 



The next change which the integument undergoes is in the development of 

 the spiral sutures, by which it is divided into two narrow bands with broad 

 and rounded ends : at first the dividing lines are indistinctly seen traversing 

 the integument (Tab. XXXIX. fig. 8.) ; after a time they become more distinct, 

 and their spiral direction becomes evident. Two lines of separation run in a 

 spiral direction round the integument, and meet in a sinuous transverse suture 

 at each end (Tab. XXXIX. fig. 11.) ; these lines cut the integument into two 

 equal parts, the ends of which are dilated and uniform ; and these are the 

 clavate ends of the filaments which have been considered by Hedwig and 

 others as forming part of a sexual apparatus. The separation of the integu- 

 ment into parts takes place immediately after the edges of the sutures have 

 arrived at their proper thickness ; it is therefore very difficult after this to find 

 the integument entire. 



At Tab. XXXIX. fig. 9. is repi-esented the most perfect which I have been 

 able to find after the examination of a great number. The spore at this time 

 contains a greenish-coloured fluid mixed with some minute granules ; soon 

 after it changes to a deeper green colour, its contents become thicker, less 

 soluble in water, and filled with a greater number of granules ; the fluid 

 which had previously filled the integument and the rest of the theca is gradu- 

 ally absorbed, leaving the granules which it contained sticking in masses to 

 the spores and to the separated portions of the integument. It is these masses 

 of granules, when found adhering to the filaments in the ripened state of the 

 spore, that have been mistaken for pollen-grains : when removed by means of 



