Spermatogenesis in Asterella hemisphaerica, Beauv. 
BY 
WILLIAM LOGAN WOODBURN, 1 
Late Associate Professor of Botany in Northwestern University , Evanston , III. 
With Plate XX. 
T HE materialifor this paper was collected several years ago, about five 
miles south-east of Bloomington, Indiana ; and it was killed in chromic- 
osmic-acetic acid. Upon working up the material the writer found that 
certain stages were not abundant, especially the last divisions of the sperma- 
togenous tissue and the early stages in the development of the androcyte, 
or the protoplast which functions as a sperm. However, since so many 
definite stages in spermatogenesis and many cytological phenomena are 
clearly demonstrated, it was thought best briefly to summarize the data at 
present available. 
Within recent years, investigators of the Hepaticae (especially in 
spermatogenesis) have reported cytological phenomena so varied that 
further information seems desirable. In an article by the writer on Muium , 
in 1915, certain of these reports prior to that date were very briefly sum- 
marized 2 . Other papers by various investigators have appeared since. 
Without repeating here in detail, we may say that the evidence indicates 
variation, throughout the group consisting of the Hepaticae 
I and the Musci, in two rather important respects : first, as to the origin, 
nature, and general prevalence of a centrosome-like structure, which is 
apparently the primordium of the blepharoplast ; second, as to the presence 
and nature of certain accessory bodies found in the cytoplasm of sperma- 
togenous cells. 
The student of botany to-day dare not draw dogmatic conclusions from 
isolated results of investigation. We are too well aware of the fact that 
( extreme variability and plasticity constitute most prominent characteristics 
of the plant cell. Yet it seems reasonable to expect that we may find 
underlying this variability the expression of Certain laws which are constant 
1 Owing to the death of the author this paper has been arranged for publication by Professor 
Atwell, of Northwestern University, and Professor Mottier, of Indiana University. 
2 Ann. Bot., xxv. 299-313, 1911 ; ibid., xxvii. 93-100, 1913; ibid., xxix. 441-56, 1915. 
[Annals of Botany, Vol. XXXVI. No. CXLIV. October, 1922.] 
