322 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Saccorhiza bulbosa. They differ somewhat from those of L.fexicaulis 

 and L. saccharina, which are here described in detail and figured. The 

 transverse divisions of the elongated embryo appear without any fixed 

 order. The first is approximately median ; and as the two cells thus 

 formed and their daughter-cells divide simultaneously or successively, 

 the embryo possesses a number either even or odd of cells, which by 

 enlarging determine the future plan of the frond. Their relative age, 

 less distinct in surface view, can always be recognized in profile, even in 

 older plants. One transverse wall, sometimes the third formed, but 

 generally a later one, separates off a flattened basal cell, from which 

 arise the first rhizoids. Soon a longitudinal division appears in the 

 central region, then in all the cells, simultaneously or unequally towards 

 the apex or the base. Two successive divisions crosswise arise then in 

 each of these cells, and so on more or less regularly. The basal portion 

 divides more slowly and remains therefore attenuated, but the proper 

 distinction between stipes and frond is not possible till a later stage. 

 The lower part thickens more rapidly by means of tangential divisions, 

 while the upper and longer part remains monostromatic. The differen- 

 tiation of the generative zone is therefore later, and less strictly localized 

 than in S. bulbosa. The median region of the monostromatic plantlets 

 of L. flexicaulis reaches generally a greater width than that of 

 L. saccharina. The first rhizoid, which often penetrates into the cavity 

 of the oogonium, becomes closely applied to its wall, which the succeeding 

 rhizoids enclose and gradually cover. The lower cell of the embryo 

 produces tw^o or three rhizoids after longitudinal division, the separated 

 cells successively producing the rest. All of them are undivided, thus 

 •differing from those of S. bulbosa. At no stage of development are 

 there any subapical initial cells of the frond, as described by Yendo for 

 the Japanese species. The author finds that the arrangement of the 

 subapical layers gains in regularity while their capacity for division 

 •diminishes and the apex attenuates. Intercalary division is generally 

 dispersed and causes the growth in length and width of the frond. 

 There is no question of marginal meristem. This is more clearly to be 

 seen in L. flexicaulis, where the meshes of the muciferous net are larger. 

 The cell-division of the embryos and plantlets of Alaria esculenta is 

 similar to that of L. saccharina and L. flexicaulis. These three species 

 differ from Saccorhiza bulbosa in the slower differentiation of the 

 intercalary generative zone. 



Marine Algae of Malmb.* — D. E. Hylmo has made a careful study 

 of the green marine alga3 occurring in the neighbourhood of Malmo in 

 Sweden and publishes his results. The first part of the paper is devoted 

 to an enumeration of the species with critical notes. In the second 

 part he deals with general considerations : — The life-conditions, including 

 •depth, composition of the substratum, salinity ; algai formations, of 

 which he recognizes seven ; seasonal changes ; comparison between the 

 vegetation (green algte) of Malmo and that of surrounding districts. 

 This comparison, in the author's opinion, is neither wholly satisfactory 



* Arkiv f. Botanik, xiv. (1916) No. 15, 57 pp. (3 pis.). 



