Physiologie. — Palaeontologie. 345 



^n Arizona were of iuller development. whiie ihose in Alabama 

 were either rather young (10— 15 cm. transversa measurement; or 

 overmature. 



It is obvious that h will be of great interest to make careful 

 measurements of growih, as indeed of other functions, for compa- 

 rison with those of Balls in Egypt. 



The stomata are practicall)'^ closed at night, but nevertheless 

 show a tendencj" to open during the early morning hours. The 

 more obvious daily opening begins at about 630, in Alabama in 

 September, and the maximum is reached at about 8.30 or 9. after 

 which closure progresses until 11 or somewhat later. A concomi- 

 tant and appreciable wilting takes place, correlatcd with the reduc- 

 tion of leaf water. During wilting there appears to be no "temporary 

 opening" of the sLomata, although the writer has observed a mea- 

 surable but not very marked rise in the rate of transpiration about 

 a half hour after wilting Starts in, followed by a sudden reduction 

 of rate. Jongmans. 



McClendon, J. F., The increased permeability of striated 

 muscle to ions during contraction. (Amer. Journ. Phj^siol. 

 XXIX. p. 302—305. 1912.) 



While the question of the positive electric Charge on the sur- 

 face of muscles is not settled yet according to the membrane theory 

 of Bernstein there is a plasma membrane or surface film surroun- 

 ding the muscle fibre which permits easier exit to some kations 

 than to the correspondings anions and these kations penetrating 

 through the surface film give the surface a positive electric Charge. 

 When this film is destroyed there is a negative Variation, and as 

 this is due to increased permeability towards any ions there should 

 be an increased conductivity on contraction of the muscle. To deter 

 mine if such is the case experiments were conducted on frog's 

 muscle and the conductivity measured by the Kohlrausch method. 

 It was found that there was increased conductivity during contrac- 

 tion and this was interpreted as demonstrating an increase in per- 

 meability to anions by some structures within the muscle, and 

 according to the membrane theory a reduction of electrical polari- 

 zation and increased surface tension and contraction. These muscular 

 structures are exceedingiy small. M. C. Merrill (St. Louis). 



Ante vs, E., Einige Bemerkungen über Cycadopteris Brauniana 

 Zigno und C. Zeüleri n. sp. (Geol. För. i Stockholm Förhandl. 

 CCCVIl. p. 376-384. Taf. 8. 1915.) 



Verf. wendet sich gegen Signora Grandoris Zusammenfüh- 

 ren von heterogenen Elementen unter einer und derselben Art wie 

 auch gegen ihre Auffassung von den Umgestaltungen der Blätter 

 und der Cuticula während der Entwicklung der Blätter. Cycadopte- 

 ris Brauniana umfasst, wie Zeiller dieselbe auffasst, zwei ver- 

 schiedene Blatttypen, eine mit getrennten Spaltöffnungstaschen, 

 eine zweite mit einer zusammenhängenden Spaltöffnungsfurche. Für 

 den letzteren Typus bringt V^erf. den Namen C. Zeilleri in Vorschlag. 

 In systematischer Hinsicht ist Cycadopteris neben Thinnfeldia u. a. 

 m. zu den Pteridospermen oder zu einer anderen ausgestorbenen, 

 jenen nahestehenden Pflanzengruppe zu führen. Autorref. 



