and Laboratory Methods. 2239 



polymorphism which is probably dependent on physical conditions. Protonemal 

 plants should be collected showing various stages in the development of the 

 Batrachospermum bud. The chantransia filament can reproduce itself by means 

 ef nonsexual spores developed on the tips of its branches. This is a case of 

 reproduction known as paedogenesis, since the process is accomplished while 

 the plant is in the immature condition. If material is at hand, draw and describe 

 the chantransia filaments and spores. 



XXX. Folysiphonia variegata (C. Ag.) J. Ag. 



Class, Florideae. Order, Rhodymeniales. Family, Rhodomelaceee. 



Folysiphonia grows in abundance on rocky sea coasts. The plants may be 

 found in summer as purplish-brown tufts, a few inches long, on other larger 

 water-plants, or on piles and stones. Preserved material may be used by those 

 living away from the seashore. 



1. Spread out a frond in a porcelain plate and sketch the entire thallus. 

 Note the hold-fast, if present, and the mode of branching. 



2. Mount a branch and draw under low power. Note that the body of the 

 thallus consists of successive tiers of cells, each tier consisting of a central cell, 

 surrounded by a layer of cortical cells. 



3. Under high power draw a single tier of cells. Crush the thallus a little 

 and note especially the large protoplasmic strands (protoplasmic continuity) 

 which run from the central cell to the several cortical cells of the tier. Note, 

 also, the strands connecting the cells of a tier with those of the tiers above and 

 below. 



4. Cut cross sections of the thallus, mount, and study under high power. 

 The sections may easily be obtained by chopping up a moist branch on a piece 

 of paper with a sharp scalpel. Draw, showing the arrangement of the central 

 and cortical cells and also the protoplasmic connections. 



5. Under high power study the tip of a young branch and draw. Notice 

 the dome-shaped apical cell and a number of cells below. The lower ones are 

 divided by longitudinal walls. How are the tiers and the cortical cells devel- 

 oped ? From this it is evident that, although Folysiphonia appears like a branched 

 filament and continues to develop as such, it finally forms a true solid aggregate. 



6. Nonsexual spore reproduction. Mount branches containing tetraspo- 

 rangia (dark spherical bodies below the cortical cells) and draw under high 

 power. Draw one of the mature spores. 



7. Sexual reproduction. The antheridia are borne on delicate, colorless 

 dichotomously branched filaments, which form tufts on the younger part of the 

 frond ; the oogonia are on short branches in the upper part. Mount branches 

 containing antheridia and draw under high power. Note the slender tip of the 

 branch which extends beyond the oblong antheridium. 



8. Development of the oogonium. Mount branches containing young 

 oogonia and under high power draw : {a) a short lateral simple branch showing 

 one of the cells considerably enlarged and more or less spherical ; (/^) one in 

 which this cell has divided by vertical cells into four cells : {c) one in which the 

 inner cell of the tier of four has enlarged and divided into three or four cells by 

 transverse walls, the upper one developing into the oogonium with a basal tricho- 

 phore and a slender trichogyne ; id') a young cystocarp showing the trichogyne 

 protruding from the mass of cells forming the wall. 



9. Draw a mature cystocarp, showing the more or less ovate-globose wall 

 and the carpostome. 



10. Crush one of the mature cystocarps and draw several of the dark colored, 

 nonsexual carpospores. Folysiphonia has an alternation of generations, since 

 the spore-bearing part of the cystocarp is homologous to the sporophyte of 

 higher plants. John H. Schaffner. 

 Ohio State University. 



