4'.>0 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Anatomical Study of Azolla filiculoides.* — C. Queva describee 

 the vascular anatomy of Azolla filiculoides. In the floating horizontal 

 stem the vascular elements of the dorsal region are narrow tracheids, 



and those of the ventral region are wide vessels. The transverse section 

 of the xylem is circular, the circle being incomplete alternately on the 

 right and left sides in the dorsal region, corresponding to the alternating 

 leaf traces. The wide ventral vessels are connected exclusively with the 

 rootlets. The interpretation suggested is that the dorsal group of 

 vessels represents a reduced bipolar group, connected at the poles with 

 leaf traces ; and that the ventral group is merely an apolar mass related 

 to the rootlets. The amount of vascular tissue is remarkable for so 

 hydrophytic a plant. 



Spore-development in Salvinia natans.t — A. Kundt describes the 

 development of the macrosporangia and microsporangia of Salvinia 

 natans. The branching of the stalks of the microsporangia takes its 

 origin in the outgrowth of any chance cell of the stem. The first 

 divisions in the capitate end-cell lead to the formation of the sporangial 

 wall — this wall remains one cell thick. The tapetum arises from divisions 

 of the central cell ; it remains always one cell thick ; and the cells mostly 

 contain two nuclei. The archesporium is divided up into spore-mother- 

 cells, sixteen in the microsporangium, eight in the macrosporangium. 

 Tetrad division is similar in both ; and stages of nuclear division occur 

 like those characteristic of the reduction in higher plants. The sporo- 

 phyte has sixteen, the gametophyte eight chromosomes. The disorganiza- 

 tion of the tapetum occurs at the time of the reduction-stage. 

 Immediately afterwards the spore-mother-cells become free in the 

 sporangium. In both kinds of sporangium the tetrads break up into 

 spores. In the microsporangium all sixty-four spores ripen ; in the 

 macrosporangium one only, rarely two. The macrospore and its nucleus 

 grow very strongly, the exospore and endospore being developed very 

 late ; and the epispore not until the spore is ripe and the tapetal nuclei 

 have disappeared. 



Aqueous Cultures of Fern Prothallia.ij: — H. Fischer describes the 

 advantages to be obtained by cultivating fern-spores on nutrient solutions 

 rather than on sand or soil. For instance, the nutrition is under more 

 accurate control ; the results are clean from sand, etc., and do not injure 

 the microtome knife ; the cultures run no risk of drying up. Different 

 results may be obtained by the employment of different depths of solu- 

 tion. Fern spores vary much in their capacity for germination. Some 

 mature slowly after being shed, and then gradually lose the power of 

 germination. Some are capable of germination after many years, for 

 instance, Ceratopteris 20 years, Asplenium serra 48 years. Again, 

 Osmunda and Todea speedily lose a'l power of germination. The author 

 failed altogether to induce Nephrodium montanum, Blechnum spirant, 

 and AUosorus crispus to germinate by any modification of his solutions ; 

 and he speculates as to why this should be. For general purposes lie 

 found the best nutrient solution to be K.,HP0 4 ' 1 p.c, MgS0 4 • 03 p.c, 

 CaCl 2 0-01 p.c, NaCl 0-01 p.c, Fe.,Cl " 0-001 p.c, NH 4 N0 3 0'1 p.c. 



* Mem. Soc. Hist. Nat. Autun., xxiii. (1910) 24 pp. (22 figs.). 

 t Beih. Bot. Centralbl., xxvii. lte Abt. (1911) pp. 26-51 (2 pis.). 

 X Beih. Bot. Centralbl., xxvii. lte Abt. (1911) pp. 54-9. 



