414 SUMMARY OF GURKENT RESEARCHES RELATING TO 



Heterogamic Sexuality of a Laminaria (Alaria esculenta). — 

 C. Sauvageau {Gomptes Rendus Acad. Sci. Paris, I'JK), 162, S40-2 ; 

 see also £ot. Oentralbl, 1*J19, 140, 74). The genus Alaria belongs to 

 tbe tribe Costatse, which is mainly distributed in tbe Arctic and North 

 Pacific ; and one species alone, out of about a score, descends as far as 

 the coast of Northern France, where it grows at Roscoff on exposed 

 rocks only accessible in a calm sea. The author has succeeded in 

 growing cultures of A. escidenta, and has studied the development of 

 the protliallus from the embryospore to the young plantlet. The male 

 and female prothalli differ from those of Laminaria flexicaulis and L. 

 saccharina by the persistence and the eventual rdle of the embryospore. 

 Also, the female prothallia differ in the form of the oogonium, and by 

 the non-transformation of all the cells into oogonia. Thus the number 







of plantlets formed is less than in the two species named. The demon- 

 stration of an alternation of generations, sexual and asexual, in A. 

 escidenta is particularly interesting as occurring in the only representa- 

 tive of Costatas, wdiich grows on the French coast. Yendo and Okamura 

 regretted that the absence of sexuality of Laminaria^ forbade the ex- 

 planation by hybridization of intermediate characters in Undaria 

 undarioides, a Japanese species of the same tribe, Costatse. This 

 explanation, now made possible, will doubtless apply to other cases and 

 throw light on certain obscurities in the specific distinction of 

 Laminaria. E. S. G. 



Researches on the Exploitation and Industrial Utilization of 

 the Principal Laminarias of the Brittany Coast. — P. Freundler 

 and Y. Menager {Office Sci. et Technique d. Peches Marit. Notes et 

 Memoires, No. 5, Angers, 1921, 31 pp.). The object of this research 

 was : (1) to study in situ the conditions of the re-growth and reproduction 

 of Laminaria, in order to ascertain how far the present method of 

 exploitation is compatible with the preservation of the algal beds. (2) 

 The investigation, in the laboratory, of a practical and industrial pro- 

 cess by which to extract simultaneously iodine and tangic acid (algine). 

 (3) The distribution of the iodine and of the tangic acid in the 

 Laminarias, according to the region, season, species, age, and the 

 different parts of the alga. As regards the first point, the authors 

 describe the three methods of collecting Laminaria for use in the 

 factory of Plouescat : (1) gathering up of jetsam ; (2) cutting by hand 

 at low tide ; (3) cutting with long-handled knives from boats, down to 

 3 m. from the surface. The last of these causes most waste and 

 destruction. As regards the possible injury to plants by cutting, it is 

 found that if the stipes be cut through it dies oft". Tf the Laminaria 

 be cut at the base of the frond, the plant survives and continues to 

 grow. The rate of growth depends on the emersion or immersion, the 

 species, the region and the season. Details of a series of experiments 

 are given. As regards the second point, two methods are described of 

 determining the proportion of iodine in fresh or dried algfe, and also of 

 iodine in extracts of algse. The necessity is insisted on of an immediate 

 partial desiccation (40-50 p.c.) before packing and despatching to the 

 laboratory. As regards the third point, preliminary experiments of a 



