ACROCHAETIUM 89 
p.p. So faras we are aware, polysporic sporangia have not hereto- 
fore been attributed to Acrochaetium or Chantransia and their 
manifest existence in the present species (the material is preserved 
with formalin) might be considered by some to be sufficient ground 
for making it the type of a new and separate genus, but so long as 
monosporangia and tetrasporangia are not considered incongruous 
іп а single generic group (Acrochaetium or Chantransia), there seems 
to be no lling reason for refusing toadmit polysporangia ; in its 
other characters, so far as the material at hand affords grounds for 
judging, the plant is clearly a member of the group which includes 
Chantransia virgatula secundata (Lyngb.) Rosenv., Chantransia 
Macula Rosenv., and Acrochaetium flexuosum Vickers, even though 
amply distinct from any of these. Тһе polyspores are, аз a rule, 
discharged in a single mass and often adhere more or less and the 
young thalli are commonly multicellular from the first. Осса- 
sional cells of the older discs occur empty and we have found some 
grounds for suspecting that cells of the prostrate discs may here 
and there be converted into sporangia, but the evidence on this 
point is not conclusive. Тһе erect filaments are nearly always 
simple, except for the often pedicelled lateral sporangia. In 
only three or four cases out of hundreds examined have we dis- 
covered a vegetative branch and in no case more than one such. 
PLATE 3I, FIGURES 1—1 т. Acrochaetium polysporum. 
I. А portion of a typical basal disc. 
2. A portion of the wanna ~ — сни disc. 
3. А portion оға in, showing ue etc, 
4. À typical erect latent: with secund sporangia, some — others wi 
-celled pedicel. car 
Ж cae erect filament, showing a single elongate br branch (obe very ) 
terminated by a young sporangium. e main axis, also, is terminated by a 
sporangium; two of the lateral sporangia are pipa the others are secund. 
with a change from one side to the other. 
6. A cell from an erect filament, showing chromatophore and pyrenoi 
7. Short erect filaments with terminal sporangia, the empty ones belag regenerated 
from below. 
8. Two lateral sporangia, showing йа. ек. Тһе sporangium wall is ruptured 
at apex. 
9. а of an erect filament showing three cells of the main axis that have been 
nverted directly into sporangia, with one sterile cell intervening. 
IO. "is concatenate sporangia of the main axis, in various stages of уйй резе 
тг. Regeneration of two emptied lateral sporangia, one sessile, the other with 
unicellular pedicel. 
