1909] CURRENT LITERATURE 73 
Centrosomes in Stypocaulon.—Since STRASBURGER and SwINGLE’s studies, 
Stypocaulon, one of the brown algae which bears a conspicuous apical cell, has 
been considered as showing typical centrosomes in thallophytes. According to 
their account, the centrosome, single at first, divides into two centers, which 
become surrounded by astral radiations. Sw1NGLE also described the kinoplasm 
as clearly distinct from the trophoplasm, the former being the only part of the 
cytoplasm concerned in the formation of achromatic spindles. 
n Grécorre’s laboratory, EscoyEez's has recently studied the origin of 
chromosomes and spindles in the nucleus of the apical cell of this plant, and his 
conclusion is quite different from that of the authors mentioned above. T 
résumé of Escoyez’s results is as follows: (1) In an apical cell, the chromosomes 
are formed at the expense of a certain part of the nuclear network, the rest and 
greater part of which remains unused. (2) A nucleolus does not take part in 
forming the chromosomes; possibly it may furnish chromatin substance to the 
forming chromosomes, since it becomes disorganized during the prophase. (3) 
In the telophase, the. chromosomes reconstitute the chromatin network in the 
usual way; a nucleolus then appears, but not by the confluence of chromosomes. 
(4) Spindles are probably of cytoplasmic origin. (5) The two asters, whose 
appearance marks the beginning of prophase, do not result from division of a 
single aster, but they are formed independently, one after the other. (6) It s 
impossible to distinguish two elements, such as the kinoplasm and trophoplasm, 
as interpreted by STRASBURGER. Very likely the central bodies which lie in 
center of asters are not true centrosomes in BoveEr’s sense. T hey give no evi- 
dence of having the nature of the true centrosomes, but represent only cytoplasmic 
microsomes.—SHIGEO YAMANOUCHI. 
Temperature of insolated leaves.—SmirH, using the new slender thermo- 
junctions of BLACKMAN and Marruatl, has determined the internal temperature 
attained by leaves placed normal to sunlight at Peradeniya.*® He finds little 
difference between thin and fleshy leaves in the final temperature attained, which 
is some 15° C. above that of the air (25-28°), but the latter are less rapidly heated. 
In the shade the same leaves are 1° °5 below to 4° above the air temperature. 
He estimates the cooling due to transpiration at 2°5, which is incredibly low, 
considering the energy required to evaporate the water transpired. Breezes, 
even the most moderate, are the more efficient cooling agents, reducing the 
temperature by 2°-r0°. Red leaves were found to attain higher temperatures 
than a white or pale leaf of like texture and thickness : 
The second part of the paper has little connection with the first, In it Suir 
tecords observations to show that the new — of a large number of trees. 
's Escovez, E., Caryocinése, centrosome et kinoplasme dans le Sree 
Scoparium. La Cellule 25: ee pl. I. 1908. 
, On the internal temperature of leaves (we omit the rest +s a 
fone title, pees Roy. Bot. Gard. Peradeniya 4: 229-298. 1909. 
