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LICHENS UNDER THE 6MICROSOPE. 673 great importance in the determinationi of species, so. that the study of lichens cannot now be successfully or thorr oughly prosecuted without an acquaintance with them. Their general form and Fig. 150. color being constant in, each genuis and species, they have, as Professor Tuckerman observes (Liche'ns of California), added a new content to the conception of species." While their study Cell)s fresh difficulties and perplexities to the student, it affords him a deeper insight into the inscrutable mysteries of 'nature, Fig. 1.51. who, whatever we may strive to ascertaili, ever holds some secrets in. reserve which are beyond our grasp. Iln its earliest stages the spore-cease _ tppeatrs -filled witl small. globlatlr gi-in- .tles, in which lines _ of division appear,- .and the spores graid, .I_ ully assume their _ regular form a n d _ iltllber. TThe spoles are at first colorless Section of pyciide of Biatora seeri. s stylospores; tla1 lus of Peltigera caninea. ald simple, and their internal d i v i s i o n & and changes of color may be seen in. all goradations in tile same hynieniuln. They frequently remain filled with a inass of oil globules. They are sometinles arrang-ed in. a linear. A.XMER. NATURALIST, vor,. IV. 85. This content downloaded from 89.240.237.181 on Sat, 11 Apr 2015 12:45:29 UTC All use subject to JSTOR Terms and Conditions
674 LICHENS UNDER THE MICROSCOPE. series in the spore-case, sometimes irregularly 'groused, and sometimes spirally twisted around a central (ideal) axis. When ripe they are expelled from the spore-case by the Fig. 152. pressure of the paraphyses, which when moistened, absorb water copiously. Many observations have been made as to the manner of the development of the thallus from the spore,: but the matter is still involved in a good deal of obscurity. Oln the thallus of most lichens are to be seen a number of small Portion of pynide of Biatora Heerti more highly magnified, showing the black dots, either scattered irreoustylospores . 1 * sty:ospes. - larly over its surface, or along -the margin. - These are the spermogonea (Fig. 148), and they contain, ill great numbers, the spermatia, which are extreirnely minute, cylindrical, or needle-shaped bodies, situated on the extremities of simple or branched filaments, called sterigomata (Figs. 149, 153). Their forms appear-to be constant in each species, but are much less diverse than those of the spores, and they are always colorless. They have been supposed to be -the male organ of reproduction, but nothing F is certainly known of their functions. Nylander, who attaches much importance to the spermatia in his Synopsis, distinguishes five forms of them. 1st, the acicular slightly swollen at one end, as in Usnea; 2d, acicular slightly swollen near the ex- Spores (a), sterigmiata and sper- , atia (ba of Bialora ileeres. trenitiy, as in Evernia; 3d, straight acicular or cylindrical, as in most tecanoras; 4th, bowed acicular, or cylindrical, as in some Lecanoras; 5th, ellipsoid or oblong, as in Calicium, which last, he says, approach rather too - near the short cylindrical spermatia. There are no spherical spermatia. But he is not fortunate in attempting This content downloaded from 89.240.237.181 on Sat, 11 Apr 2015 12:45:29 UTC All use subject to JSTOR Terms and Conditions
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