324 Howe: Observations on the 



enlarged outer end : rhizoids often irregularly inflated and filled 

 with densely granular reserve-food materials: stipe 1-2.5 cm. 

 (mostly 1.5 cm.) long, .28-.48 mm. in thickness : primary sterile 

 branches 8-18 in a whorl (commonly solitary), finally 4 times 

 (rarely 5 times) polytomous, the ramuli usually in 4's, the 

 ultimate often in 3*s or 2*s. 



The membranes throughout are thinner in the Bermudian 



plants than in the Brazilian, though susceptible to some variation 

 in both. The wall in the apical region of the mature sporangium 

 is in the former mostly about 9 fi in thickness while in the latter 

 it ranges from 12 ft to 24 fi (measured after decalcification in 

 both). But in only one sporangium, out of many examined, of 

 the specimens collected by Dr. Schenck, have we seen the mem- 

 brane relatively so thick as is indicated in Mobius' figure 12 (Hed- 

 wigia, 28 : pL 10. 1889). Again, the coronal processes in the 

 Bermudian plant are less emarginate or lobed and the hypopeltal 

 processes less often show a tendency to become twice dichoto- 

 mous, but these characters are extremely variable in both. 



Professor Schenck writes that his specimens also were col- 

 lected in a mangrove formation. 



Apart from the other important differences, Acicularia Schencka 

 is very distinct from Acetabulum crenulatum (Lamx.) Kuntze in 

 general habit and appearance, differing at first sight in being 

 much smaller in all its parts and in the nearly flat discs. 



By using some care, the contents of a mature sporangium can 

 be removed in a single coherent conico-prismatic or subcuneate 

 mass (Figs. 37 and 38), as happens in nature by the decay of the 

 sporangium wall. By reflected light, under low magnification, one 

 of these bodies appears white, with the light green aolanospores 

 occupying slight depressions or pits on the surface, but higher 

 magnification shows that the pitted appearance is largely an optical 

 illusion ; for unless the aplanospores have collapsed in the process 

 of preservation — which sometimes happens even in formalin 

 material — their outer surface is on about the same level with 

 the surrounding matrix. It is a point of some biological interest 

 that the side of the aplanospore which lies toward the surface 

 of the massula is always the one which bears the lid, and in the 

 lid region, so far as we have observed, is always free from the 



