304 Physiologie. 



Harreveld, Ph. van, On the penetration into merciiry 

 of the roots of freely floating germinating seeds. 

 (Proceed. Kon. Akad. v. Wet. Amsterdam. Sept. 26, 1903.) 



An explanation is given of the well-known, old experiments 

 of Pinot afterwards repeated by Wigand, in which growing 

 roots of loose lying seeds penetrate to a considerable extent 

 into the mercury on which they are placed. The author repea- 

 ted these experiments, and others in the same Hne^ to be found 

 in literature and shows that the explanation of the seeming 

 physical paradox is not that of Durand and Du t röchet, 

 viz fixation of the seeds by a resistent layer formed on the 

 mercury, as has been generally accepted. The facts as origi- 

 nally described by Pinot and Wigand are on the contrary 

 quite correct and can be easily explained by the support, given 

 to the seeds by the tensiön of the concave surface of water 

 raised through capillarity against the seeds or between them. 



Moll. 



HowE, Marshall Avery, Physioiogical studies. I. New 

 Chlorophyceae Irom Florida and the Bahamas. (Bul- 



' letin of the Torrey Botanical Club. XXXII. p. 241—252. 

 pl. 11 — 15. May 1905.) 



Halimeda scabra sp. nov. is described as resembling H. tiina 

 in form and habit, but is distinct from this as well as other 

 species of the genus in always possessing „strongly galeate- 

 cuspidate peripheral utricies". Sporangiophores are not distinc- 

 tive. A weil-defined plug consisting probably of a callous 

 mucilage cuts off the sporangium of //. scabra and the same 

 structure, although not so well formed, was made out in what 

 is believed to be H. tiina. 



Siphonocladiis rlgldus sp. nov. is probably related to 

 6*. brachyartriis but is much larger and coarser. Zoospores 

 are doubtfully recorded, and cysts are of common occurrence. 

 The constant presence of what appears to be the hyphae of 

 some fungus is noted and the possibility of future investigations 

 demonstrating the analogy of vS. rigidiis and other forms with 

 the Lichens is suggested. 



The new genus Petrosiphon, placed in the Valoniaceae, 

 with the Single species P. adliaerens is described. Petrosiphon 

 is allicd to Siphonocladiis, but its „flat, compact, crustaceous, 

 more or less calcareous thallus, with determinate outline and 

 radio-marginal growth" distinguishes it from this genus. P. ad- 

 haerens, which is common in the Bahamas, grows in tide 

 pools and on calcareous rocks near low-water mark. A fungus 

 appears to usually accompany the species. Cysts (aplano- 

 spores) are frequent but no other method of reproduction was 

 discovered. Moore. 



