348 [summary of current researches relating to 



new description of Achnanthes in data Gran., and figures it ; hitherto 

 there has been no proper definition of its characteristics. A new variety, 

 var. madeirensis, is described for Aulacodiscus amain us (Ire v. 



Vaucheria synandra.*- — P. E. Kaiser records for the first time an 

 instance of Vaucheria synandra growing inland, far from the sea. It 

 appears to flourish and fruit in a ditch near the brine baths at Elmen, 

 near Magdeburg in Germany, together with V. dichotoma. V. synandra 

 showed the characteristic antheridia and oogonia. The locality in which 

 it was growing was saturated with brine and other well-known halo- 

 phytic algag, and diatoms were found there. The author believes that 

 V. Thuretii was also growing in the same place, but is unable to confirm 

 absolutely the belief, since the actual spot where that species was found 

 has since been interfered with. 



Saccorhiza bulbosa.f — F. Tobler publishes a few remarks on this 

 alga, of which he has studied many examples, both fresh and in herbaria. 

 He draws up a comparative table of seventeen specimens, giving the 

 length of the frond, development of the organ of attachment, length 

 of stem, etc. He states that the length of the stem has no connec- 

 tion with the depth of the habitat, and that when the stem has reached 

 a certain degree of development, the peculiar frilled growth is discon- 

 tinued. 



Zoning of Brown Seaweeds.} — S. M. Baker has continued her 

 investigations into the causes of the zoning of brown seaweeds on the 

 sea-shore. The experiments described in the present paper were carried 

 out with a view to determining the influence of periodic desiccation on 

 the germination, and also on the dehiscence-mechanism of the four 

 species under observation — namely, Fur us platycarpus, Ascophyllum 

 nodosum, Fucus vesiculosus, and F. serratus. The four species grow in 

 this order from the high-water line downwards. The author finds that 

 those algse which grow in the upper zones are capable of resisting desic- 

 cation both during germination and vegetative growth. Also their 

 receptacles are protected by being filled with mucilage, and this seems 

 to make their dehiscence-mechanism most efficient when they are dry 

 for a considerable length of time. Also, in both F. spiralis and Asco- 

 phyllum nodosum the paraphyses project considerably from the ostioles 

 of the conceptacles ; and this may be an adaptation to ensure the 

 gametes being very rapidly expelled during the short time they are 

 covered by water. Experiments with F. spiralis point to this conclusion. 



The alga? growing in the lower zones have become adapted to very 

 rapid growth ; they are thus able to supersede the more skw -growing 

 and protected forms, in their own zones, but at the same time they have 

 not the power of resisting desiccation, so that they cannot grow in the 

 upper zones. Also their dehiscence-mechanism has become efficient for 

 very short times of exposure ; and they are able to choke out any stray 

 member of a higher zone, growing lower down, which cannot compete 

 with them in the number of reproductive bodies given off. 



* Hedwigia, xlix. (1910) pp. 400-2. 



t Kong. Norsk. Videusk. Selsk. Skrift., No. 6 (1908) 9 pp. (1 pi.). 



j New Phytologist. ix. (1910) pp. 54-67. 



