DEC 2 8 1910 
The Ohio ^atura list, 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
L1BRAF 
NEW YO 
BOTANIC 
GARDE 
Volume XI. DECEMBER, 1910. 
No. 2. 
TABLE OF CONTENTS 
Wells— A Histological Study of the Self-dividing Laminae of Certain Kelps 217 
Briggs— Viola Hirsutula in Ohio 232 
Henninger — The Macro-Lepidoptera of Seneca County, Ohio 233 
Schaffner — Leaf Markings of Certain Ohio Plants 243 
SCHAFFNER — New and Bare Ohio Plants added to the State Herbarium in 1910 24li 
Stover — Notes on Ohio Agarics II 247 
Dickey— M eeting of the Biological Club 24S 
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 
formation 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 system 
of branching more 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 (1899) in his observations on Nereocystis gives a 
* Contribution from the Botanical Laboratory of the Ohio State 
University, 59. 
217 
