274 



MacMillax : Observations on Nereocvstis 



♦ 



to speak with absolute certainty of any plant under one-half milli- 

 meter in length. The reason for this is that the youngest plants, 

 collected m two feet of water off San Juan Island at lo A. iM., 

 June 5, 1898, during the lowest low tide of the year, are mingled 

 with young Costaria Mcrtcnsii^ Lauii)iaria sacchariua and Alaria. 

 It is difficult to distinguish the young stages of Laminariaceae 

 from each other and this difficulty increases Inversely with the 

 age of specimens. Yet a careful comparison of sections shows 

 structural peculiarities which enable one to speak with some degree 

 of certaInt}^ 



The first published reference to young JVnrocysfis plants and 

 the first descriptions of their fruiting structures are those of Ares- 

 choug In a paper In the Swedish journal, Bot. Notiser of 1876. pp. 

 65-73 '^^^^^ '^^^ Obser\\Mtiones Phycologlcae. In the first paper Ares- 

 choug describes his Pdagophycus gigantcus under the name of 

 Ncrcocystis gigantca. In this article he describes the young uni- 

 laminatc plant and explains how the lamina is split vertically and 

 how each half is repeatedly split. He describes the change in 

 shape of the pneumatocyst as it develops and makes some anatom- 

 ical observations upon the mucilage ducts Avhich are quoted later 

 by Guignard. The resemblance of the }^oung A^cirocystis plant to 

 young Laininanac was apparent to him. 



The only previous American reference that I have found to 

 young Ncrcocystis plants — in which, I have been unable to dis- 

 cover anv^ addition to the facts set down bv Areschou^^ thirteen 

 years before- — Is in one of the more recent papers of Professor 

 W. G. Farlow of Harvard University who, in the Bulletin of the 

 Torrey Botanical Club for 18S9, comments upon a series of young 

 plants presented to him by Miss Lenncbacker, concerning which, 

 however, I ha\'e not learned that he ever published further. The 



' w 



smallest plant he mentions was four inches In length and he states 

 that the ** bladders begin to show themselves when the plants are 

 about eight Inches long." It is possible, however, by the sense of 



touch to distinguish the pneumatocyst in material but three centi- 

 meters In length and the organ becomes visible as a slight expan- 

 sion of the stipe shortly after. Professor Farlow, with Areschoug, 



observed the resemblance of the immature plants to young Lami- 

 nariaceae of the digitate section, possibly basing his statement 



J * 



