LINDSAY, ON A BROTH ALL US 53 



lichens — Scututa. Their relation to the function of reproduc 

 tion has yet to he determined. In certain respects they bear an 

 analogy to the spermatia ; in certain other respects to true 

 spores. They are generated in conceptacles closely resem- 

 bling, in site and external form, tlie spermogones ; they also 

 appear to precede the spores in order of development, and to 

 be rather cotemporaneoiis with the spermatia; they are 

 moreover, extra-thecal or extra-cellular, and are thrown off 

 from the apices of peculiar filaments or stsrigmata. On the 

 other hand their size and form, and the nature of their con- 

 tents, approximate them more to the character of true spores. 

 There is a remarkable resemblance, hov/ever, between the 

 stylospores and the pyriform or obovate bodies described as 

 the spermatia of the Peltigerne by Tulasne {' Mem.,' p. 200) . 

 The section of a spermogone of Peltigera precisely resembles, 

 in the form and arrangement of its sterigmata and spermatia, 

 the pycnidis of Abrothallus. A careful investigation will 

 demonstrate that there is a regular gradation, in form and 

 size, between the ordinary, straight, rod-shaped, minute 

 spermatia of ParmeUa pariethia, P. physodes, or PJiyscia 

 ciliaris ; the ovoid spermatia of Lichina confinis and L. 

 pygmcea, or of Urceolaria caJcarea and U. scrvposa ; and the 

 pyriform, comparatively large spermatia of Peltigera canina. 

 From the anatomy of the genus Abrothallus, — which alone, 

 however, is not sufficient to decide a question of such impor- 

 tance, — I am strongly inclined to regard the pycnides as 

 merely an unusual form of spermogones, and hence unde- 

 serving of a separate designation and consideration. In A. 

 Smithii, I have already stated 1 have never observed sper- 

 mogones; and in A. oxysporus 1 have not met with pycnides. 

 But the pycnides appear to bear precisely the same relation 

 — in regard to site, predevelopment to the apothecia, &c., — 

 to the former, that the spermogones do to the latter. They 

 are, therefore, probably endowed with similar functions, and 

 act as substitutes for each other. Korber also regards the 

 pycnides as the analogues of sj^ermogones, for he says : " Ich 

 halte dieselben fur Analoga der Spermogonien, die, in der 

 gewohnlichen Form, bei Abrothallus zu felilen scheinen, 

 wobei freilich die bedeutcndere Grosse der Stylosporen vor 

 derder spermatien der uljrigen Flechten selir auffallig ist" 

 (p. 215). Prior to the elaborate researches of Tulasne and 

 other carefvQ observers, the pycnides would undoubtedly have 

 been regarded as the reproductive organs of some parasitic 

 fungus. But we now know that some of the more minute 

 fungi possess so many as four or five different kinds of repro- 

 ductive bodies; and from the close affinity between the 



