1908] CURRENT LITERATURE bay | 
Aerotropism.—Potowzow has taken up the question of the response of plant 
organs to gases.2*_ Reserving the usual term aerotropism for sensitiveness to the 
mixture of gases that compose the air, he proposes the term aeroidotropism for 
sensitiveness to pure gases. This seems an unnecessary refinement of terms. Very 
properly he criticizes the use of roots as subjects for experiments with gases, since 
the organ is under wholly unnatural conditions, and uses stems, which SAMMET 
tried with negative results. Potowzow finds Brassica Napus, B. Rapa, Vicia 
sativa, V. Faba, Pisum sativum, Lupinus albus, Phaseolus multiflorus, and Helian- 
thus annuus sensitive to O, and CO,, but unaffected by Hand N,. The grasses 
studied were all indifferent. At the beginning there is a positive curvature, which 
becomes more rapid, slows, ceases; shortly a negative curvature sets in, gradually 
increasing. When stimulation ceases, curvature slows, stops, and then the 
recovery of the normal position takes place. The active region may be a centi- 
meter or more distant from the perceptive region, which may even be in the part 
of the stem that has ceased growing, showing that perceptive capacity persists 
longer than capacity for the curvature reaction. The perception time was found 
to be 0.5 sec. with o.or°¢ of CO, and periods of stimulation and rest in the ratio 
1:3. The reaction time was found to be not much more than in various tactic 
responses; PoLowzow thinks because the movements in both cases were exam- 
ined by the microscope, and he pleads for the use of the more refined methods of 
the animal physiologists. There is certainly nothing to prevent; Bosr has 
blazed the path. We hope that in the full paper to which this is preliminary the 
the author will give us such records and discuss more fully some general questions 
Taises.—C. R. B. 
Seed production in Pinus.—Under this title HayDon”? presents the results 
of as extended field study supplemented by cytological work. The cytological 
conditions found in both microsporangiate and megasporangiate cones at various 
Seasons are noted in detail. The staminate cone, in the vicinity of Liverpool, 
Passes the winter in the spore mother cell stage. The megaspore mother cell ap- 
pears about the end of May, but its origin was not determined. Occasionally 
large ventral canal cells are formed, and in a few cases the first mitosis in the 
aly observed when there were no traces of pollen tubes or other evidences of 
robeerang HAyDon believes this supports the suggestion of the reviewer? 
hic: large ventral canal nucleus might fertilize the egg. The simultaneous 
ns at the base of the egg by which the proembryo passes from the 8-celled 
say ee 12-celled stage is sometimes in the lower tier instead of in the upper 
oe lly the case. Theoretically, the ovulate cone might produce some 
Pe — W., Experimentelle Untersuchungen iiber die cone UNTER . 
liufige sa besonderer Beriicksichtigung der Einwirkung von Gasen. 
ae ng. Ber. Deutsch. Bot. Gesells. 26a: 50-69. 1908. ' 
a OE apg WaLtTER T., The seed production of Pinus sylvestris. (Inaugura 
a roc. and Trans. Liverpool Biol. Soc..22:1-32. figs. 16. 1907. 
OT. Gazetrr. 423349. 1906. 
