Physiologie. — Algae. 407 



seedlings grown after geotropic Stimulation, at approximatel}^ 16° C. 

 Tests of seedlings were made during various intervals of the Präsen- 

 tation and reaction time. The convex and the concave halves of the 

 shoots were separated for analysis. In general it was found that 

 acidity is greatest at the tip and decreases downward. With respect 

 to the two flanks, there is a change during the presentation and 

 reaction time; the concave side becoming first more acid and then 

 diminishing in acidity until the maximum is found on the convex 

 side. Subsequently the two flanks become equal, and this corresponds 

 to the time of visible curvature. Nevertheless, the acid increase is 

 not parallel to the measureable rate of growth on the two flanks. 



Duggar (St. Louis). 



Skinnep, J. J., Effect of solanin on the potato plant. (Plant 

 World XV. p. 253—256. 1912.) 



The growth of young potato plants in distilled water and in 

 extract of potato soil was found to be seriously interfered with 

 when solanin was added to such Solutions. 



A. R. Davis (St. Louis). 



Harper, R. A., The structure and development of the 

 colony in Goniuni. (Amer. Micr. Soc. Trans. XXXI. p. 65—82. 

 pl. 5. t. fig. 1-8. 1912.) 



This is primarily a study of the space relations of the cells in 

 a colony in order to cast light upon the interactions of cells, and 

 their influence in heredity and ontogeny. In general, the colonies 

 consist of 16 cells forming a square with truncated corners, somewhat 

 octagonal in outline. It is shown that the 8 cells making the corners 

 of the Square are in contact each with 3 cells, the middle cell of 

 each side is in contact with 4, and each of the 4 interior cells is 

 in contact with 6 cells, — thus the series of curves described by 

 Cohn are brought about. It is fundamental that the successive planes 

 of division intersect at right angles. The colony Organization, in 

 Short, corresponds to the type of division involved in the formation 

 of the cells. 



It follows that the colony form is not dominant in determining 

 the division planes in new colony formation; that is, "cellular 

 Organization" is important, and not heredit}^ of form for the whole 

 organism. Undoubtedly the readjustments in the positions of the 

 cells with the growth of the colony are towards stability and 

 compactness. That the colonies are under considerable pressures as 

 between the different parts is shown by their behavior. Regeneration 

 of injured cells does not occur. ' Duggar (S. Louis). 



Stiasny, G., Das Plankton des Meeres. (Sammlung Göschen. 

 N^ 675. G. J. Göschen'sche Verlagshandl. 160 pp. 83 Fig. 1913.) 



Auch für Vorgeschrittene ist dieses Büchlein zu empfehlen, da 

 es die neuesten Ergebnisse der marinen Planktonkunde bringt und 

 verwertet. Es war dem Verf. gleichsam ein Bedürfnis, seine in der 

 Adria gewonnenen Kenntnisse mit der Literatur über das Thema 

 zu einem Ganzen zu vereinigen, was ihm auch ganz gut gelungen 

 ist. Die Gruppierung des Stoffes ist folgende : Geschichte der Plankton- 

 forschung, die Lebensbedingungen des marinen Planktons, die Or- 

 ganismen des Planktons (Pflanzen und Tiere), Vergleich des Süss- 



