OF ARTS AND SCIENCES. 63 



or else, descending through an interuode to the next node below, 

 there change their course and 2:)roceed out to the surface. Occasion- 

 ally some of them grow obliquely downwards and outwards, but this 

 method is not a common one. The branches are generally very 

 numerous at a node, and form a dense ring surrounding it. 



The antheridial branches are cylindrical, and at first unbranched. 

 At the ends, which are situated at or just beneath the surface of the 

 frond, they are two or three times branched in a corymbosely dichoto- 

 mous fashion. They are composed of cylindrical cells, two to four 

 times as long as broad, and resemble in general appearance the sec- 

 ondary filaments described above. The contents of the cells, how- 

 ever, are less decidedly green, being more of a bluish-gray color, more 

 homogeneous and granular, and containing no conspicuous chroma- 

 tophores (cf. Figs. 21 and 22). 



The antheridia are borne at the tips of the branches, are spheroidal 

 in shape, of an opaline tint, and with granular contents. In the 

 centre is a large spot of greater refractive properties than the rest of 

 the contents. On being liberated from the autheridium, the sin£;le 

 antherozoid is, for a short time at least, of an irregular shajje, and has 

 a slight amoeboid motion, but it soon becomes globular and motion- 

 less. After the antherozoid has been discharged, the basidial cell 

 may grow through into the empty sac of the antheridium and produce 

 there a new antheridium. One frequently finds the antheridium en- 

 closed in two or three ruptured sacs, showing that the process may 

 be repeated several times. A stage of this process is illustrated in 

 Figure ^'2. 



The antheridia in shape, color, and character of contents exactly 

 agree with those of Batrachospermum, and in these respects differ 

 from those of Lemanea. The antheridia of Batrachospermum, how- 

 ever, are borne singly, or in twos or threes, on various cells of the 

 unmodified ramelli. In Lemanea, on the contrary, they are all borne 

 at the nodes, and are situated at the tips of a special layer of dichoto- 

 mous, short filaments. In this, then, as will be seen from the above, 

 Tuomeya differs decidedly from Batrachospermum and approaches 

 Lemanea. The necessity for having the antheridia situated in the 

 external layer in Tuomeya, as well as in Lemanea, is probably to be 

 found in the possession of a sohd frond by both of these genera. If 

 borne in the interior of such a frond, the antherozoids would have 

 difficulty in being carried from plant to plant by the currents. In 

 Batrachospermum the difficulty is not so great, yet even here the 

 antheridia are borne on the outer joints of the ramelli rather than on 



