Bibliographical Notices. 383 



from this approximation is not uniform, for a number of intermediate 

 states occur between certain species whose tissue is so loose in the 

 centre that the filaments which are condensed towards the outer sur- 

 face leave the centre almost tubular {M . fistulosa) , and the new spe- 

 cies described below, which presents almost a cartilaginous consist- 

 ence. Be the consistence however what it may, the axillary or 

 longitudinal filaments are tubular, articulated, cylindrical, or slightly 

 strangulated at the points of articulation, transparent hyaline or of a 

 pale greenish yellow, from the presence of a small quantity of gra- 

 nular matter in the articulations. They take an oblique direction 

 towards the circumference, anastomosing occasionally with the neigh- 

 bouring threads ; not however, as Meneghini and Decaisne have well 

 observed, and as the latter has shown in his figure of Nemalion muU 

 tifidum, J. Ag., without sending forth at the same time, here and there 

 towards the interior, far more delicate, dichotomous, articulated, and 

 perfectly hyaline filaments, which help doubtless by their interlacing 

 to double the consistence of the frond. The last articulation of the 

 axillary thread, when arrived at the circumference, is elongated into 

 a horizontal filament with much shorter articulations, strongly con- 

 stricted at the dissepiments, but gradually increasing in breadth as 

 they approach the surface, whence they have a more or less strongly 

 pronounced clavate form. In the Brazilian species, these threads, 

 which are very long, are perfectly cylindrical and not thickened above. 

 Each of the articulations of which they are composed contains a green 

 endochrome of various tints at different stages of growth or in dif- 

 ferent species, whose form is correlative with that of the articulation. 

 Sometimes it is not a simple filament which terminates the extreme 

 cells of the axillary tissue, but either it is dichotomous, or a certain 

 number are united at the base, from whence also proceed the recur- 

 rent filaments. It is usually towards the inferior portion of the radia- 

 ting filaments that the two kinds of organs are fixed which appear to 

 serve equally towards the propagation of the species ; sometimes hoM'-- 

 ever it is from the summit itself that they proceed, resemblmg in this 

 other Phi/coidea. The one which are unanimously considered as true 

 spores are composed of a simple, entire, undivided nucleus, consist- 

 ing of green or brown granules inclosed in a hyaline perispore, which 

 forms a transparent limb round the nucleus. These spores are, 

 according to the particular species, spherical or obovoid ; the other 

 organs are regarded by the younger Agardh as metamorphosed radia- 

 ting filaments, and called by him propagules. Meneghini, who has 

 observed their coexistence with what he calls sporiferous utricles, 

 considers them as a second form of fructification analogous to the 

 siliculseform capsules of the genus Ectocarpus*, to which in fact they 



* Kiitzing considers the specimens with podlike fruit as individuals 

 having a second form of fructification. Mrs. Griffiths however, who has 

 paid great attention to the genus, does not assent to tliis view, there being 

 a pecuhar habit in each of the pod-bearing species which makes it almost 

 impossible to refer them as mere forms to any of the other species. The 

 subject is however well worth attention, and can be deteunined only by those 

 who can study the species in situ, — Edit. 



