JAN 7 -1908 
The Ohio %)\£aturalist, 
PUBLISHED BY 
The Biological Club of Ihe Ohio State University. 
Volume VIII. DECEMBER. 1907. Ho. 2 
TABLE OF CONTENTS 
IIerms— Contribution to the Life History of Asimina triloba .. 2H 
Morgulis —Compensatory Growth in Podarke obscura. 217 
Morgulis —Regeneration and Inheritance.. .21!i 
Hine— Descriptions of New North American Tabanidae. . ..221 
CONTRIBUTION TO THE LIFE HISTORY OF ASIMINA 
TRILOBA.* 
William B. Herms. 
The material for this study was collected in the outskirts of 
Columbus, 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-ace tic acid, within 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, 190.5, 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 ovulary 
was imbedded in paraffin and serial sections cut ten microns 
thick with a rotary mircotome. Several st*aining methods were 
emlpoyed, of which the double 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 Laboratory 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 eventuallv 
give rise to the archesporial cell. This undifferentiated condition 
is retained throughout the winter as is evident from Fig. 2 (Jan. 
G). The first sections showing the archesporial cell, which is 
* Contributions from the Botanical Laboratory of the Ohio State University', XXXII. 
