1914] CURRENT LITERATURE 87 
many different stages irregularities in chromosome distribution may occur in a 
variety of ways. GarTES believes several characters of O. gigas cited by DE 
VRIES as occurring independently of chromosome doubling are the result of 
the tetraploid condition with its larger cells and nuclei. Many such differences 
are attributed to causes fundamentally quantitative. The interpretation of 
Nursson, that O. gigas originates by the accumulation of factors for size, is 
held by Gates to be contradicted by the cytological facts and by the sudden 
origin of giant types with their subsequent wide variation. Although some 
Oenothera characters are Mendelian in their behavior after they appear, Men- 
delian combinations in NILsson’s sense are inadequate to account for their first 
appearance.—L. W. SHARP. 
A heterosporous fern.—LIGNIER*™ has published a new genus (Mittagia) 
from the Lower Westphalian strata, which is the first heterosporous fossi 
fern to be described. That such a group did occur is, of course, postulated by 
the existence of the seed ferns, but this is the first demonstration of its presence. 
Licnigr, too, has sounded a note of warning by his discovery. He was at 
first inclined to consider that his sections were of a pteridosperm, Lagenostoma 
Lomaxi, so similar in structure are the outer tissues of the sporangia in the 
two forms. When he found four megaspores to a sporangium, a stomium pres- 
ent, and the sporangia arranged in a sorus, he knew that he had something 
different. His sporangium, however, he considers did not dehisce, and so, 
like Lepidocarpon, is a stage toward the seed habit. His conclusion that the 
sporangia belonged to a fern is based chiefly on their structural resemblance 
to Lagenostoma, and on their arrangement in a sorus. He has further dis- 
tinguished them from the lycopod and equisetum lines, from Lepidécarpon, 
Miadesmia, Selaginella, heterosporous calamites, etc. LicNreR’s intensive 
study of the small amount of material at his disposal and his logical deductions 
are exceedingly interesting and valuable—R. B. THOMSON. 
Evaporation in Skokie Marsh.—Using the Livingston atmometer, SHERFF*% 
measured the evaporating power of the air in a marsh habitat near the city of 
Chicago during the summer of 1911. The average daily rate of evaporation for 
the lowest stratum of vegetation was 3 cc. for the Typha association, 4.27 cc. 
for the reed Swamp, 4.5 cc. for the swamp meadow, and 7.9 cc. for the swamp 
forest of Quercus bicolor and Fraxinus americana. This forest is normally 
antecedent to a truly mesophytic forest such as that found by the reviewer to 
have an average daily rate of 8.1 cc.* During September and October of the 
ie 
* Licnrer, O., Un noveau sporange séminiforme. Mém. Soc. Linn. Normandie 
24:49-65. 1913. 
a * Suerrr, E. E., Evaporation conditions at Skokie Marsh. Plant World 16:154- 
- I9t2, 
% Bor. Gaz. 52:193-208. rgrt. 
