Physiologie. 243 



growing, and we do not know whether the conditions which deter- 

 mine rest are identical with those determining rest in the egg. We 

 know, however, that specific substances circulating in the blood 

 can induce certain resting cells in the body to grow and that these 

 substances differ apparently for different types of cells. It may be 

 that in the body substances antagonistic to these may enforce the 

 inactivity of the cells. The circulation in animals or the flow of 

 substances in plants is an important factor in the phenomena of 

 cell rest and cell growth, inasmuch as circulation or flow determine 

 or influence the distribution of formed cells or non-formed Clements 

 which induce or influence growth. The phenomena of regeneration 

 seem to find to a large extent their explanation in the fact that a 

 wound or mutilation leads to a gathering of formed or non-formed 

 Clements in Spots where without the mutilation they would or could 

 not have collected. Matouschek (Wien). 



Loeb, J. and H. Wasteneys. On the identity ofheliotro- 

 pism in animals and plants. I — II. (Proceed. nation. Acad. 

 Sc. I. 1915. p. 44-47 and Science. N. S. XLI. No 1052. p. 328—330. 

 1915.) 

 The validity of the Bunsen-Roscoe law for the heliotropic 

 reactions of certain (and possibly all) plants and animals suggests 

 that these reactions are due to a chemical action of the light. There 

 seem to exist two heliotropic substances, one with a maximum of 

 sensitiveness (or absorption) in the yellowish-green (near l = 534 fi^) 

 and the second with a maximum of sensitiveness in the blue (near 

 i. =z All fxfi). Visual purple is a representative of the former type. 

 The photosensitive substance of the Visual purple type occurs in the 

 Protozoon ChlantydomonaSj which is usually stated to be a plant, in 

 Daphnia and many other organisms. The photosensitive substance 

 with the maximal sensitiveness in the blue is found in Eiiglenüj in 

 many plants and in certain animals, e. g., -Ew^^wß^rmm and probably 

 others. It would, therefore, be wrong to State that the one type of 

 photosensitive substances is found exclusively in plants and Ihe 

 other exclusively in animals. As a matter of fact they are distri- 

 buted independentlj'- of the systematic boundaries between the two 

 groups of organisms. It is immaterial for the theory of heliotro- 

 pism to which of the two types the photosensitive substance in 

 any given heliotropic organism belongs. Matouschek (Wien). 



Pfeffer, W., Ueber die Verbreitung der haptotropischen 

 Reaktionsfähigkeit und das Wesen der Tastreizbar- 

 keit. (Ber. Sächsischen Ges. Wiss. Leipzig, math.-physik. Kl. p. 

 93-120. 1916.) 



Drei Abschnitte umfasst die Arbeit: 



Ausblick auf die von P. Stark im bot. Leipziger Institute aus- 

 geführten Untersuchungen über die Verbreitung der Tastreizbar- 

 keit, kritische Betrachtungen über das Wesen der Tastreizbarkeit, 

 Zusammenfassung der bisherigen Studien über das Verhalten der 

 Ranken bei Berührung von zwei gegenüberliegenden Seiten. 



Matouschek (Wien). 



Pfeiffer, T„ Kruziferen und Gramineen hinsichtlich der 



