those counties that I did not see are more fertile than the im- 

 mediate vicinity of the Michigan Central R. R. However, the 

 figures for Norfolk County alone (which seems to have the largest 

 proportion of evergreens) indicate somewhat poorer soil. It has 

 41.5 inhabitants per square mile (a decrease of 9.5% in twenty 

 years), 30.4% of them in incorporated places, 13.0% farm wood- 

 land, 21.4% pasture, 40.9% field crops, and the farm land is 

 worth only $37.70 per acre. 

 Tallahassee, Fla. 



A NOTE ON THE INTERRUPTED FERN 



N. M. Grier 



I observed at Hanover, N. H., specimens of the interrupted 

 fern, {Osmunda Claytoniana, L.) which did not conform to the 

 descriptions for this species in that the number of fertile pinnae 

 was greater than five pairs or even less than one. I was led to 

 examine many other plants to see if a predominating number of 

 fertile pinnae could be established for this species, since the 

 descriptions of the manuals state that two to five pairs are pre- 

 sent. This seemed further justified because of the probability 

 that the species was described from a fewer number of specimens 

 than I first examined. 



A field in which this fern was one of the dominating species 

 enabled me to secure counts from 609 fronds growing under three 

 different conditions so far as the light factor was concerned. 178 

 of those observed belonged to plants fully exposed in the open, 71 

 to some growing completely in the shade of trees, while the 

 remainder, 360, were from the border of the field adjacent to the 

 woods where they received the full effect of the sunlight 

 during part of the day only. It was noted in about 16% of all 

 the cases that only portions of the fertile pinnae had developed 

 sporangia, sometimes as little as one-third of the pinna being so 

 occupied. Regardless of the proportion of it occupied by spor- 

 angia, a fertile pinna was counted as one. 



All observed fertile pinnae were grouped by classes and a 

 frequency polygon plotted. This indicated that 3 pairs were 

 the most commonly distributed, making up 24% of the total 

 number. Minor modes of the curve, (all percentages are ap- 



