Mr. Henderson on the Reproductive Organs o/'Equisetiim. 571 



and even retained their activity. Alcohol appears to produce no other effect 

 on the granules, except the immediate suspension of their motion. Iodine acts 

 upon the larger ones, which it changes to a bluish colour ; but it produces no 

 very obvious effect on the lesser ones, except rendering them more distinct. 



I have found both these kinds of granules in the unripe thecse of Ferns, of 

 Lycopodium and of Ophioglossum : in the latter the larger ones are spherical, 

 very numerous, and some of them very large; the whole of the cells of the 

 theca are filled with them in the immature state of the spore, but they are 

 mostly absorbed during its maturation, and very few remain after the dis- 

 charge of the spores from the theca. Active granules exist also in some (if 

 not all) the lower tribes of Cryptogamous plants : I have found them in the 

 unripe thecae of Mosses and of several species of Jungermannia, in the apo- 

 thecia of Lichens, and in the lamellae of Agarics, and the perithecia of some 

 other Fungi : in some Agarics they are so minute as only to be rendered visible 

 under a high magnifying power by diluting the water with iodine. On com- 

 paring these granules with those contained in the unopened anthers of flower- 

 ing plants, they appear to me to be in every respect identical ; in both cases, 

 where the larger ones occur, they are similarly acted upon by iodine, and are 

 therefore probably of the same nature ; in the theca they appear to occupy a 

 similar place with those in the cells of the anthers, and they decrease in like 

 manner during the progress to maturity of the pollen-grain and of the spore. 

 In the granular contents of the spore also there is the most perfect resemblance 

 to those of the pollen-grain*. Perhaps the most obvious difference is in the 

 entire absence of green colour from the fluid of the latter. 



It has been already observed, that while the changes which have been 

 described are in progress in the spore and its integument, considerable 

 changes are also produced in the organization of the theca. Tab. XXXIX. 

 fig. 1 & 2. represent two sides of that organ in its immature state, and as it 

 appears up to the time when the spores which it contains are in the state 

 represented at Tab. XXXIX. fig. 10. At this time it is a thin, transparent, 



* In the manner in which the spores of Equisetum, Ophioglossum, Psilotum, and perhaps all the 

 higher tribes of Cryptogamous plants, originate in their thecae, there is a strong resemblance to the 

 origin of pollen in the antherae as described by Brongniart, namely, " in the interior of the cells of a 

 single and distinct cellular mass." 



VOL. XVIII. 4 F 



