1921] CURRENT LITERATURE 77 
mately 40 per cent higher than the unlimed; that the oxidizing power varies 
inversely with its lime requirement; that nitrate accumulation and bacterial 
numbers were higher on the limed soils, whereas the ammonia accumulation 
was about the same for all of the plots; that the average crop yield for the 
past 10 years varies closely with the present oxidizing power of the soils; and 
that there is a noticeable correlation between crop yield, nitrate accumulation, 
and bacterial numbers, but not between crop yield and ammonia accumulation. 
PARKER and Truoe! find a rather close relation between the calcium 
and nitrogen content of plants. The contents of potassium, phosphorus, and 
magnesium do not bear this close relation to the nitrogen content. There are 
two groups of agricultural plants, those having a low calcium-nitrogen ratio 
and a low lime requirement, and those having a high calcium-nitrogen ratio 
and a higher lime requirement.—W. CROCKER. 
Arctic Caryophyllaceae.—A critical study of the morphology and ecology 
of the Caryophyllaceae is one of WARMING’sS most recent contributions to the 
science of ecology. He divides his report into four parts, dealing respectively 
with (1) morphology and vegetative propagation, (2) leaf anatomy, (3) adapta- 
tions to environment, and (4) flower biology and seed reproduction. 
In the first section he recognizes and describes several growth forms, 
illustrating by drawings of typical plants and listing the species to be referred 
to each form. Numerous variations of the rosette and cushion forms are dis- 
tinguished, and multiplication by buds, offshoots, runners, and layers is care- 
fully discussed. The details of the leaf structure are to be obtained from the 
drawings, the most important generalization being the usual absence of xero- 
morphic features. Palisade tissue is poorly differentiated, the mesophyll has 
abundant large intercellular spaces, stomata usually occur on both surfaces, 
and the epidermis is thin-walled and but slightly cutinized, the leaves thus 
resembling those of hydrophytes or shade plants. In this respect they form 
a striking contrast with the xeromorphic leaves of the woody evergreens of 
the same regions. 
Among the most conSpicuous features of the flower biology is the common 
occurrence of both protandry and polygamy, the latter being accompanied by 
varying degrees of reduction of stamens in the ovulate flowers. Very - 
quently the corolla is decidedly smaller in the ovulate flowers.—Geo. D. 
LER 
wn and barley yield——Hartan and AnrHony® have found that early 
removal of the awns of barley greatly reduces the volume and dry matter of 
4 Parker, F. W., and Truos, E., The seein between the calcium and the 
nitrogen content of plants and the function of calciu il Science 10:49-56. 1920. 
5 WarminG, ENG., The structure and biology oa Arctic flowering plants. 13. 
Poitn ogee Meddelelser om Grénland 37:228-342. figs. 44. 1920 
, and AntHony, S., Development of barley kernels in normal 
and eran ‘jin and the Seaton? of awaless and hooded varieties. Jour. Agric. 
Research 19:431~472. 1920. 
