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XXXVIII. On the Reproductive Organs of Equisetuiii. By Mr. Joseph 

 Henderson. Communicated hy the Rev. M. J. Berkeley, M.A., F.L.S. 



Read June 2nd, 1840. 



1 HERE is no part of the structure of Equisetum more curious or more 

 anomalous than the organs of reproduction ; and although the position of the 

 order in the natural system depends on the nature of these organs, yet this is 

 so far matter of doubt, that very eminent botanists do not seem decided as to 

 whether Equisetacece are to rank among Phsenogamic or Cryptogamic plants. 

 In the following observations* (the result of an examination continued 



* These observations were made before I was aware that in part they had been anticipated. Tre- 

 viranus (a) appears first to have observed and correctly figured the spiral vessels in the cells of which 

 the thecse of Equisetum are composed ; and Meyen (i) confirms his observations, while he at the same 

 time criticises, and with justice, the account given by BischofF(c). There are, however, several points 

 that appear not to have been examined, and my observations do not precisely accord with those of 

 Meyen. I venture, then, still to offer them to the notice of the Linnean Society, trusting that I shall 

 be excused if in any case I have been occupied on ground which has already been explored. 



Since the present paper was read, Mr. I. J. Bennett has kindly pointed out to me that I have also 

 been in a great degree anticipated by Mohl in the discovery of the peculiar mode of the production of 

 the spore in Equisetum. I think it right, therefore, to give a translation of the passage in his memoir, 

 which has been furnished by a friend. 



" The young capsules (of Equisetum variegatum) are filled with a very delicate, polyhedral, cellular 

 tissue. These cells are connected together in greater or lesser masses, without, however, being sur- 

 rounded by mother-cells (if they are not rather themselves to be so regarded), and are filled with a 

 granular mass. In older capsules these cells are larger and distinct from each other, and the green 

 granular contents form for the most part a disc lying in the middle of the cell. In still more advanced 

 capsules this green disc is changed into an oval grain, wrapped round with the two elaters. These 

 seem to arise from the splitting of the cell in which the grain is formed, and at first surround it under 

 the form of a closed integument. The grain itself possesses two coats, of which the outer is mode- 

 rately tough, the inner very tender. I have never seen a style-like elongation like that with which 

 Hedwig has represented the grain." — Flora, 1833, pp. 45, 46. 



(a) Von inwendigen Ban d. Gew., pp. 89. & 120. tab. 2. fig. 29. 



(b) Meyen, Pflanzen-Physiologie, vol. i. p. 59, 1837. 

 (e) Bischoff, die Krypt, Gew., i. p. 39. 



