Mar., 1923 ] 
SHOWALTER — RICCARDIA PINGUIS 
163 
torium. My observations on these early stages do not accord with hers, 
but are too fragmentary to justify a questioning of her results. 
Summary 
1. Riccardia pinguis is a cosmopolitan species whose morphological 
features very somewhat under different environmental conditions. 
2. The species is probable dioecious, but the male and female thalli 
are distinguishable only by their reproductive branches or by the presence 
or absence of sporophytes. 
3. The spores when discharged from the capsule do not ordinarily 
adhere in tetrads, but the tetrads may be preserved by proper manipulation. 
4. The growth of the thallus is apical, by means of a “two-faced” 
apical cell which gives rise to segments alternately from its right and left 
cutting faces. 
5. The early divisions of the primary segment of the apical cell follow 
the scheme of Leitgeb (1877). 
6. The axial row of the archegonium develops from a mother cell which 
divides to form a central cell and a neck-canal mother cell; the latter divides 
once, increasing the axial row to three penultimate cells which divide in 
acropetal succession forming ultimately an egg, a ventral canal cell, and 
four neck-canal cells. Occasionally, the number of penultimate cells is four 
instead of three and the ultimate number of neck-canal cells six instead of 
four. 
7. Disintegrating archegonia are numerous in the material used for 
this study; the egg and ventral canal cell frequently break down before the 
maturity and disintegration of the neck-canal cells. 
8. The young embryos found in this material show an order of division 
slightly different from that reported by Miss Clapp (1912). 
9. A massive “calyptra” is formed around the sporophyte by the rapid 
growth and division of the cells of the venter and of the cells of the thallus 
immediately below the archegonium. 
I wish to acknowledge my gratitude and indebtedness to Dr. W. N. 
Steil, who gave valuable assistance in procuring material; to Mr. Severin 
Rapp of Sanford, Florida, who supplied living plants from his locality; 
to Professor A. W. Evans of Yale University, who confirmed the identifi¬ 
cation of all material used and gave valuable suggestions; and especially to 
Professor C. E. Allen, under whose guidance these studies were made. 
Department of Botany, 
University of Wisconsin 
LITERATURE CITED 
Campbell, D. H. 1896. Development of Geothallus tuberosus , Campbell. Annals Bot. 
10: 489-510. 
