502 BOTANICAL GAZETTE [DECEMBER 
figures of transverse sections of stomata show that any noticeable widening 
‘s the slit in the ordinary - is impossible, because of the very thick cell 
The guard cell, however, can move a little as a whole, because it is 
satincdy sineci with the sin ae cell. The general conclusions reached are 
as follows: a movement as described by SCHWENDENER for grass stomata is 
impossible; the guard cells can vary their distance from each other to a slight 
extent by changing their position among the surrounding epidermal cells; 
the position and structure of the neighboring cells makes it possible to change 
the length of the slit in the vertical direction —J. M. C 
Internal temperatures of plants——PEARSON’’ has made observations on 
internal temperatures of the stems of Euphorbia virosa and Aloe dichotoma at 
4200 ft. altitude, on the western flanks of the great Karasberg Range in Great 
Namaqualand. Euphorbia reached its maximum at about 2:00 P.M., about 
the same hour as the shade maximum; while Aloe attained its maximum after 
and 5° C. respectively for Aloe. These observations were made in Decem-’ 
ber. It is likely that in February and March both the internal maximum 
temperature and the excess over shade temperature is much greater. 
Xerophytes have much reduced transpiration, the greater of the two cooling 
methods in mesophytes, and depend largely upon thermal emissivity for cooling. 
Even in mesophytes as great difference between shade and internal leaf temper- 
atures have been observed as are recorded here, and in xerophytes much 
greater differences. The author observes that wounding Euphorbia causes 
a considerable fall in the nace temperature. This is due partly to expan- 
sion of gases in the air chambers and partly to rapid ees from the 
wound.—WILLIAM CROCKER. 
Javanese Pallavicinias——CAMPBELL and Miss WirttAms” have recently 
completed a study of three species of Pallavicinia collected by Professor 
CAMPBELL in Java in 1906. The apical cell in the three species is dolabrate, 
being similar to the usual condition in P. Lyellii, which, however, the reviewer 
has observed rarely has a triangular pyramidal cell similar to the one in P. 
decipiens. The antheridium in development shows the usual situation among 
Jungermanniales. A delicate wall separates the pairs of spermatocytes. No 
“‘Nebenkérper,” reported by IkeNo for Marchantia, was found. The arche- 
gonia present few variations from the usual liverwort conditions. In P. 
5 PEARSON, H. H. W., Observations on the internal epee of Euphorbia 
virosa and Aloe dichotoma. Annals Bolus Herb. 1:41-66. 
© CAMPBELL, D. H., and WILLIAMS, FLORENCE, A Rseane study of some 
members of the genus Palloviointe: Poleat Seantord Jr. Univ. Pub. 7, Univ. Series, 
Pp. 44. figs. 23. 1914. 
