-346 



THE MICROSCOPE AND ITS REVELATIONS. 



these be watched with sufficient attention, the rupture of some of the 

 thecae and the dispersion of the spores may be observed to take place 

 whilst the specimen is under observations in the field of the Microscope. 

 In sori, whose capsules have all burst, the annuli connecting their two 

 halves are the most conspicuous objects, looking, when a strong light is 

 thrown upon them, like strongly-banded worms of a bright brown hue. 

 This is particularly the case in Scolopendrum, whose elongated sori are 

 remarkably beautiful objects for the Microscope in all their stages; until 

 quite mature, however, they need to be brought into view by turning 

 back the two indusial folds that cover them. The commonest Ferns, in- 

 deed, which are found in almost every hedge, furnish objects of no less 

 beauty than those yielded by the rarest exotics; and it is in every respect 

 a most valuable training to the young, to teach them how much may be 

 found to interest, when looked for with intelligent eyes, even in the 

 most familiar, and therefore disregarded, specimens of Nature's handi- 

 work. 



342. The ( spores ' (Fig. 231, A) set free by the bursting of the thecae, 



Development of Prothallium of Pteris serrulata: A, Spore set free from the theca: B, Spore 

 beginning to germinate, putting forth the tubular prolongation a, from the principal cell b; c, first- 

 formed linear series of cells; D, Prothallium taking the form of a leaf -like expansion; a, first, and 

 6, second radical fibre; c, d, the two lobes, and e, the indentation between them; f, /, first-formed 

 part of the prothallium; g, external coat of the original spore; h. h, antheridia. 



usually have a somewhat angular form and are invested by a yellowish or 

 brownish outer coat, which is marked very much in the manner of pollen- 

 grains (Fig. 277) with points, streaks, ridges, or reticulations. When 

 placed upon a damp surface, and exposed to a sufficiency of light and 

 warmth, the spore begins to ' germinate;' the first indication of its vege- 

 tative activity being a slight enlargement, which is manifested in the 

 rounding-off of its angles. This is followed by the putting-forth of a 

 tubular prolongation (B, a) of the internal cell-wall through an aperture 

 in the outer spore-coat; and moisture being absorbed through this, the 

 cell becomes so distended as to burst the external unyielding integument, 

 and soon begins to elongate itself in a direction opposite to that of the 

 root-fibre. A production of new cells by subdivision then takes place 

 irom its growing extremity: this at first proceeds in a single series, so as 



