igi6] ROE—SPLACHNIDIUM 407 



9. Linnaeus, C. von, Mantissae Plantarum. Holmiae. 1767. 



10. Mitchell, M. O., and Whitting, F. G., On Splachnidimn rugosum Grev., 

 the type of a new order of algae. Phyc. Mem. 1 : 1-10. pis. 1-3. 1892. 



11. Murray, G., Introduction to the study of seaweeds. London. 1895. 



12. , On the cryptostomata of Adenocystis, Alaria, and Sacchorhiza. 



Phyc. Mem. 2:59-63. pi. 16. 1S93. 



13. Oltmanns, F., Morphologie und Biologie der Algen. Jena. 1905. 



14. Roe, M. L., The development of the conceptacle in Fucas. Bot. Gaz. 

 61:231-246. ph. 14-17. 1916. 



15. Sauvageau, C., Sur la sexualite heterogamique d'une Laminaire {Saccho- 

 rhiza bulbosa). Compt. Rend. Acad. Sci. 161:796-799. 1915. 



16. , Sur les debuts du developpement d'une Laminaire {Sacchorhiza 



bulbosa). Compt. Rend. Acad. Sci. 161:740. 1915. 



17. Smith, A. L., and Whitting, F. G., Notes on the sori of Macrocystis and 

 Postelsia. Phyc. Mem. 1:84-86. pi. 20. 1895. 



18. Suhr, J. N. von, Beitrage zur Algenkunde. Flora 24:257-298. 1840. 



EXPLANATION OF PLATES XIV-XVIII 



All the drawings were made with the aid of the Abbe camera and reduced 

 one-half in reproduction. For figs. 1-2 1, original magnification was 1580; 

 for fig. 22, 790; and for figs. 23, 24, 1050. 



Fig. 1. — Modified superficial cell, showing heavy coat of mucilage which 

 distinguishes initial row from other border cells. 



Fig. 2. — Two-celled stage of initial row. 



Fig. 3. — Three-celled stage of same. 



Fig. 4. — Two stages in development of initial rows; a two-celled stage 

 at right and an older stage at left in which some of the cross-walls have been 

 resorbed. 



Fig. 5. — A linear row of the thallus, showing mucilage coat characteristic 

 of an initial row. 



Fig. 6. — An initial row in which cross-walls have been almost completely 

 resorbed; traces of old walls still distinguishable. 



Fig. 7. — A cut showing how initial row is usually terminated by sister 

 cells, one of which usually fails to mature but sometimes initiates a young 

 hair, as in fig. 8. 



Fig. 8. — An initial row together with a young hair. 



Fig. 9.— Basal portion of a branch of an apical hair which has become an 

 "initial." 



Fig. 10. — Lateral branch and basal portion of apical hairs which have 

 become "initials." 



Fig. 11.— Basal portion of an old apical hair in which cross- walls have 

 been resorbed; the upper portion (unshaded) will be shed later. 



Fig. 12. — An ordinary vegetative hair characteristic of apical region. 



