rg1t] CURRENT LITERATURE 323 
in proportion to the like linear dimensions of the surfaces than in proportion 
to the surfaces. He has also shown that for equal surfaces isodiametric sur- 
faces give least evaporation, and that the greater the deviation from the 
isodiametric the greater the evaporation. These facts are related to the 
gives great importance in the absence of air currents. He concludes that the 
deviation from the linear dimension law, under conditions cited in the first 
sentence, is in large part due to convection currents set up by the moist air 
over the evaporating surface being less dense than the surrounding dry air. 
In the present work,® by means of wet filters and water surfaces, RENNER 
studied in great detail the effect of shape, size, position, and proximity of 
evaporating surfaces in both still and moving air. Later he expects to carry 
these studies over to leaves, where the part played by internal rn can 
also be determined. —WILLIAM CROCKER. 
Theories of heredity.—In a discussion of two theories of heredity, that 
the nucleus is and that it is not the sole bearer of hereditary qualities, LunbE- 
GARD" devotes most of his space to a study of the literature, but also $ 
the various constituents of the cell in root tips of Vicia Faba. In the first 
part of the paper he comes to the conclusion that the nucleus cannot be the 
substances found in cells. He believes that the mitochondria do not come 
from the nucleus, and that they are not bearers of hereditary qualities. Here 
again the reviewer is not convinced and, in the present state of the subject, is 
inclined to think that at least some of the bodies known as mitochondria are 
of nuclear origin. Plastids also are considered, and the view of SCHIMPER 
and others, that the plastid is a permanent organ of the cell, is upheld.— 
CHARLES S J. CHAMBERLAIN. 
feo Pe 4 } 
Heterochromosomes.—That there is a d 
has been recognized for some time by zoologists, but it is only 1 more recently 
that botanists have turned their attention to the subject. In the wild mul- 
berry (Morus indica) TAHARA’ finds, in early stages of prophase in sporophyte 
nuclei, paired chromatin masses which may be called pronuclei, and even at 
13 spi O., Zur Physik der Transpiration. Ber. Deutsch. Bot. Gesells. 29: 
125-132, 1911 
** LUNDEGARD, HENRIK, Ein Beitrag zur Kritik zweier Vererbungshypo 
Ueber Piece | n den — von Vicia Faba. Peery 
Wiss. Bot t. 48: 285-378. pls. 6-8. 19 
*s Tanara, Masato, Ueber die Toe bei Morus. Bot. Mag. Tokyo 24: 
281-289. pl. 9 
