Ig10] CURRENT LITERATURE 75 
trichia Fr. Braun from the Mesozoic of Franconia is introduced. The result 
of the present important communication is to enlarge our knowledge of the 
male organs of the Bennettitales by seven different species belonging to five dif- 
ferent types. Two species of Williamsonia have monosporangiate strobili. The 
same condition is clearly demonstrated in Cycadocephalus. The author wisely 
refuses to commit himself as to the nature of the Bennettitean inflorescence, 
and avoids any reference to its possible homology with the angiospermous flower. 
—E. C. JEFFREY. 
Réle of ammonium salts.—PRIANISCHNIKOW,'S working with grasses, has 
already shown that a substitution in sand cultures of 4-3 of the NaNO, by (NH,), 
SO, increases the power of the plant to gain cna acid from raw phos- 
phates (phosphorite), while in absence of (NH,),SO, the plants show phosphoric 
acid starvation. Total substitution, however, greatly reduces the harvest. Bot 
these effects are attributed to the released sulfuric acid. In partial substitution 
the acid was strong enough to aid in dissolving the phosphorite, and in tota 
substitution so strong that it greatly injured the plants. It is also shown that 
CaCO; is very effective in preventing injuries by (NH,),SO,, and if only }-4 
enough was used to neutralize the liberated sulfuric acid, the consumption of 
the phosphorite was also much favored. In working with barley, peas, and buck- 
wheat, the author has determined that mixtures of NaNO, and (NH,),SO, are 
better sources of nitrogen than either one alone, for, as he states, the first is physio- 
logically basic (base liberated due to the consumption of NO, as source of nitrogen) 
and the second physiologically acid (acid liberated due to the consumption of 
NH, as the source of nitrogen). e two maintain the culture medium neutral. 
The author does not attempt to decide between the relative values of ammonium 
salts and nitrates as a source of nitrogen when the former are of very weak acids, 
as those used by RirTEr* to settle this question for fungi —WILLIAM CROCKER. 
Fossil conifers.—NatHorst!? has described with truly admirable clearness 
and judgment the cones of the problematical coniferous genus Palissya from the 
Rhaetic of Schonen in Sweden. The ovuliferous cone scales are characterized 
by the presence of two rows of opposite seeds, with very loose integuments or 
epimatia. The author concludes that the evidence of the organization of the 
cone scales tends to connect the genus with a second genus described in the article, 
namely Stachytaxus. This genus has yewlike foliage, and attached to the ends 
of the twigs are lax cones with distant scales, each of which bears two ovules, 
provided with a widely flaring integument or possibly an epimatium comparable 
with that found in the Taxineae. The author argues for the taxineous affinities 
1s PRIANISCHNIKOW, D., Zur oo Characteristik der Ammoniumsalze. 
Ber. Deutsch. Bot. Gesell. BRE ee 
‘© Ber. Deutsch. Bot. Gesell. 27: See 1909 
17 NatHorst, A. G., Paleobotanische Mitteilungen. 7- Handi. Kgl. Svensk. 
Vetensk.-Akad. 43: no. 8. 1909. 
