The Ohio ^J^aturalist, 



PUBLISHED BY 



The Biological Club of the Ohio State Uni'versity. 



Volume VIII. DECEMBER, 1907. No. 2 



TABLE OF CONTENTS 



Herms— Contribution to the Life History of Asimina triloba 211 



MoRGULis— Compensatory Growth in Podarke obscura 217 



MoRGULis — Regeneration and Inheritance 219 



HiNE— Descriptions of New North American Tabauidae 221 



CONTRIBUTION TO THE LIFE HISTORY OF ASIMINA 



TRILOBA.* 



William B. Herms. 



The material for this study was collected in the outskirts of 

 Colurnbus, Ohio, along the banks of the old canal, where the 

 papaw grows quite abundantly. The young buds were killed 

 in a one per cent, solution of chromo-acetic acid, Avithin ten to 

 twenty minutes after collecting them. Before killing, the sepals 

 and petals were removed to secure better penetration. 



The first collection was made Sept. 30, 1905, and continued 

 weekly until the middle of December, when collections were made 

 every two weeks until the middle of February, at which time 

 weekly collections were again resumed. During the early part of 

 June collections were made twice per week. The entire ovularA- 

 was imbedded in parafhn and serial sections cut ten microns 

 thick with a rotary mircotome. Several staining methods were 

 emlpoyed, of which the dotible stain anilin-safranin followed by 

 gentian violet was the best for the early work on the megaspores 

 and microspores, while Delafield's Haematoxylin gave the best 

 results for the later stages, e. g., development of the embryo 

 sac and late microspores. 



The work was carried on in the Botanical Laborator}' of the 

 Ohio State University under the direction of Professor J. H. 

 Schaffner to whom the writer wishes to express his thanks for 

 advice and helpful criticism freely given. 



Ovules and megaspores. The first sections cut of Sept. 30, 

 1905, (Fig. 1), showed an undifferentiated condition of the 

 ovules. No cell could be distinguished that might eventually 

 give rise to the archesporial cell. This undifferentiated condition 

 is retained throughout the winter as is evident from Fig. 2 (Jan. 

 6). The first sections showing the archesporial cell, which is 



^^ * Contributions from the Botanical Laboratory of the Ohio State University, XXXII. 



