The Ohio ^I\(^aturalist, 



PUBLISHED BY 



The Biological Club of the Ohio Stale Uni'versity, 

 Volume XI. DECEMBER, 1910. No. 2. 



TABLE OF CONTENTS. 



Wells— A Histological SUuly of the Self-dividiiig LamiLiae of Certain Koliis 217 



GuiGGS— Viola Hirsiitttla in Ohio 2o2 



IIenn'INGER— The ilaoro-Lepidoptera of Seneca County, Ohio 233 



ScHAFFNER— Leaf ^Markings of Certain Ohio Plants 2-13 



ScHAFFNEK — Xew and Hare Ohio riants added to the State IIerl)arinni in 1910 24t) 



Stoveii — Notes oil Ohio Agarics 11 247 



LicKEY—Meetinu of the Biological CluV) 248 



A HISTOLOGICAL STUDY OF THE SELF-DIVIDING 

 LAMINAE OF CERTAIN KELPS.'= 



Bertram W. Wells. 



Among the brown algae the family Laminariaceae or the 

 kelps, besides comprising the largest species of algae, display in 

 many other ways peculiarities of extreme interest. One of these 

 is a novel and unusual method of branching, exhibited by several 

 of the genera, a character which has caused them to be placed 

 in a sub-family, the Lessoneatae. In this group branches are 

 formed, not as outgrowths from the growing point, which in all 

 the kelps is intercalated between the stipe and blade, but by the 

 fonnation of a perforation through the growing region, which 

 upon elongation divides the lamina and to a greater or less extent, 

 the stipe also. Taking Nereocystis as typical of the subfamily, 

 a glance at Fig. 1 will make clear this peculiar branching habit. 

 The figure shows a very young plant in which the primary split 

 has divided the original blade and secondary splits are seen 

 fairly started. In Nereocystis lines of modified tissue are always 

 seen running out in advance of the splits. These appear even 

 before the basal perforation is developed, as seen in Fig. 1, b. 

 The repetition of this process of division goes on until hundreds 

 of laminae are found attached to the basal bladder by a systein 

 of branching inore or less dichotomous in character. 



A few writers on the Lessoneatae have given some attention 

 to the histological processes involved in developing the fissures. 

 MacMillan (1S99) in his observations on Nereocystis gives a 



* Contribution from the Botanical Laboratory of the Ohio State 

 University, 59. 



217 



