18 AUKIV FÖR BOTANIK. »AND 17. N:0 1. 



ivinaiii finuly unitod in a distiiictly circuiuscribcd cluster. 

 The difficulty is to separate the spores from each other, and 

 usually this cannot be done sufficiently well to permit of a 

 counting of the spores. In some cases, however, the contents 

 of the sporangium arc less densely compressed, and the spores 

 can be separated individually or into little groups in which 

 the number of spores can be counted or at least estimated 

 with reasonable accuracy. A counting of the spores in seven 

 different sporangia gave the following results: 221, 224, 410, 

 412, 413, 414, 438. 



The figures obtained are strikingly divided into two 

 groups, the'' one with the numbers 221 and 224, the other 

 ran^ino- from 412 to 438. As particular care was taken that 

 no portions of adjacent sporangia should adhere to those of 

 which the contents were counted, it is n^ore probable that in 

 the case of the lower figiu'cs the whole contents of the sporangia 

 were not secured for the counting. The wide gap between 

 the two groups, however, and especially the fact that the 

 higher figures are nearly the double of the lower may also 

 suggest that the number of spores actually varied by the double 

 according as there was one division more or less in the for- 

 mation of the mother-cells. The typical number of spores in 

 each sporangium may thus be taken to be either always 512 

 or else sometimes 25« and more often 512. 



If any importance be attached to the size of the sporangia 

 and the number of spores in each sporangium, Dictyophylhmi 

 cannot unreservedly be referred to the Dipteridinae, which 

 have the typical polypodiaceous number of 64 spores in each 

 sporangium. The sporangia of DictyojpMjlhim are not only 

 much fewer in number in each sorus and much larger than 

 those of DiiJteris (Nathorst 1906, p. 19; cfr. pi. 2, figs. 15— 

 16 and fig. 18 of this paper) but also of a different shape, being 

 globular or lenticular, and not pear-shaped and tapering to- 

 wards the stalk as in Dipteris. The annulus consists of a 

 somewhat greater number of cells in Dictyophylhmi (about 

 30) than in Dipteris (20) and it is more nearly complete. 



A comparison with Matonia also shows a fairly great 

 difference, though the number of sporangia in each sorus 

 is the same. The sporangia of Matonia are larger than those 

 of Dipteris, which is remarkable in view of the fact that the 

 number of spores is stated to be the same (Seward 1899, 



