ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 4G5 



New Chlorophyceae.* — M. A. Howe issues the first of his phycologicat 

 studies and describes in it three novelties : Halimeda scabra, Siphono- 

 cladus rigidus, and Petrosiphon adherens — the latter representing a new 

 genus. Halimeda scabra differs from all the known species of the genus 

 by having always strongly galeate-cuspidate peripheral utricles, and these 

 spines are so large that they can be seen under a lens. The author finds 

 the plant in various exsiccata under the name of H. Tuna, which it 

 resembles in outward form. The fruit is described and figured. A 

 septum usually cuts off the contents of the sporangium from the 

 sporangiophore, recalling Codium. Siphonocladus rigidus has been found 

 distributed under the name of S. tropicus, and is also closely related to 

 8. brachyartrus Svedelius. Petrosiphon is a genus of Valoniaceae, and is 

 allied to Siphonocladus, but differs from it by having a flat, compact, 

 crustaceous, more or less calcareous thallus. The last two species 

 described are infested by a fungus, which appears to be parasitic. 



Siphonocladus.j — F. Borgesen publishes some contributions to a 

 knowledge of the genus Siphonocladus. He holds that the genus should 

 be divided, and he forms from it a new genus Cladophoropsis. This is 

 to include S. membranaceus, S. fasciculatus, S. brachyartrus, S. voluticola, 

 S. Zollingeri, S. modonensis, S. psyttaliensis, and possibly some other 

 species. The original genus, Siphonocladus, includes only S. pusillus 

 and S. tropicus. (It may be added as a parenthesis that the plant 

 published as No. 1081 in Phycotheca Boreali-Americana under the name 

 of S. tropicus, is not that species but a new one, S. rigidus M. A. Howe.) 

 The principal characters of Siphonocladus and Cladophoropsis are drawn 

 up and printed side by side, and the author describes in detail a species 

 of each genus, S. tropicus and C. membranacea. Figures are given of 

 various points of structure. 



Chlorochytrium.l — F. S. Collins makes some interesting remarks on 

 this genus and on G. Lemnce, in particular. He gives the distribution of 

 the three marine species known in America, and then describes the life 

 history of the fresh-water species, G. Lemnm, which he has found in 

 specimens of Lemna trisulca from Seabrook, New Hampshire. He 

 recommends a search for Chlorochytrium in other host-plants than those 

 already known. 



Polarity and Organ-Formation in Caulerpa prolifera.§ — J. M. 

 Janse has made a series of careful experiments with a view to elucidating 

 these points. Polarity in the cell being very difficult to investigate, he 

 chose for experiment the large unicellular green alga, Caulerpa prolifera, 

 and studied the streaming currents of its protoplasm both in the normal 

 state and after local injuries. There are two sorts of current ; one is 

 green and nutritive ; the other colourless and composed of meristem- 

 plasm. Both are basipetal, and not easy to reverse by artificial means ; 

 but in leaves cut off and planted upside down the green current was 

 more or less capable of reversal, the results being interfered with by the 



* Bull. Torrey Bot. Club, xxxii. (1905) pp. 241-52 (5 pla.). 



t Overs. Kgl. Dansk. Vidensk. Selek. Forh., 1905, pp. 259-91 (13 figs, in text). 



\ Khodora, vii. (1905) pp. 97-9. 



§ Proc. K. Akad. Wetensch. Amsterdam, vii. (1905) pp. 420-35. 



Aug. 16th, 1905 2 I 



