1024 SUMMARY OF CURRENT RESEARCHES RELATING TO 



a deep sea is an erroneous one. The seaweeds belonging to tlio 

 Lithothamniere, which abound in the Gulf of Naples, contain only 

 from 5 to 6 per cent, of organic matter, marly the entire substance 

 consisting of mineral matter, chiefly carbonate of lime. On death 

 these plants do not change their form, but become gradually trans- 

 formed into a structureless substance altogether resembling chalk. 



Physiological Anatomy of Algae.* — flerr N. Wille publishes in 

 greater detail the result of his observations on the various adaptations 

 found in the structure of seaweeds to their mode of life. 



Abnormal Forms of Vaucheria.f — Mr. D. II. Campbell describes 

 some singular abnormal developments of Vaucheria geminata Vauch. 

 var. racemosa. After being kept for a week or two in rather confined 

 quarters, a large proportion of the fertile branches developed ab- 

 normally. 



In one the antheridium was replaced by a filament in all respects 

 like an ordinary vegetative filament ; while in another the antheridium 

 was perfect, but the oogonia were replaced by slender filaments. In 

 another example one oogonium had developed, but its apex was pro- 

 longed into a filament; and, again, in another the antheridium was 

 complete, but one of the lateral buds had developed a secondary 

 branch bearing a complete set of sexual organs, a perfect antheridium, 

 and four perfect oogonia. A further abnormality consisted in an 

 addition to the ordinary antheridium of two others with accompanying 

 oogonia from the lateral buds. Finally, in another example, one of 

 the lateral buds had grown out into a filament which bore laterally a 

 smaller branch upon which a perfect antheridium and oogonium and 

 a rudiment of a second oogonium were formed. 



Japanese Desmids.J — Messrs. J. Koy and J. P. Bisset describe a 

 number of desmids from a lake called " Junsai numa," in the island 

 of Yesso, Japan. By far the larger number of species are European, 

 but several new species are described, comprising four of Cosmarium, 

 seven of Staurastrum, one of Xanthidium, one of Docidium, and one of 

 Sphserozosma. 



Structure of the Diatom Valve.§ —Mr. J. Deby says that he has 

 in his collection a series of well-mounted slides, which have proved, 

 to his satisfaction, the following facts, most of which are corrobora- 

 tive of previous observations by others : — 



(a.) That the shell of most diatoms consists of a double plate. 



(b.) That between these two plates there exist a greater or less 

 number of cavities surrounded by solid walls of silica. These cavities 

 are circular or hexagonal in outline. 



(c.) That in all recent living and perfect valves the cavities are 

 closed at the top by the upper plate, and at the bottom by the lower 



* Svensk. Vetens.-Akad. Haudl., xxi. (1S86) 78 pp. (8 pis.). See Bot. 

 Ceutralbl., xxvii. (1886) pp. 1, 245-7. Cf. this Journal, v. (1885) p. 841. 

 t Amer. Naturalist, xx. (1886) pp. 552-3 (7 figs.). 

 X Journ. of Bot., xxiv. (1886) pp. 193-6, 237-42 (1 pi.). 

 § Journ. Quek. Micr. Club, ii. (1886) pp. 308-18. 



