president's address. 681 



Verson* and Frenzelf also adduce particular cases of direct 

 nuclear division which, as they maintain, are incapable of being 

 ex[)]ained in accordance with Ziegler's view. 



BiitschliJ has reiterated and reinforced in the course of the 

 last year the arguments in favour of his view of the nature of 

 protoplasm. By his experiments with certain " emulsions," first 

 described by him several years ago, he claimed to have efiected 

 something towards elucidating the real nature of living protoplasm, 

 and also towards explaining as purely physical and chemical some 

 of the phenomena characteristic of living protoplasm, and commonly 

 set down as manifestations of purely vital forces. 



Biitschli's method of experimenting is now well known. With 

 thickened olive oil is mixed finely powdered carbonate of potash. 

 When a drop of this mixture is placed on a slide and covered with 

 a cover-glass, under which water is run, it exhibits, when examined 

 under the microscope, remarkable streaming movements resulting 

 in change of shape and of position, so that it bears some resem- 

 blance to a gigantic living Amoeba. The drop has a vesicular or 

 frothy character owing to its consisting of numerous minute 

 vesicles containing soapy substance separated by thin layers of oil. 



We have here a very complex system of contending surface 

 tensions, a system in which very slight influences acting from the 

 outside, such as currents in the surrounding water, may alter the 

 balance of the whole ; some of the superficial vesicles burst ; this 

 disturbs the balance of the tensions in the neighbouring parts, 

 and the disturbance passes through the drop, with the result that 

 a streaming movement is brought about, and a resulting change 

 of shape. 



It is contended that the movements of living protoplasm are in 

 some cases so like those of this artificial representative that the 

 former is probably similar as regards its general physical condition 



* Biol. Centralbl. 1891, p. 556. 



t " Zur Bedeutung der amitotischen (dh-ekten) Kerntheiluug." Biol. 

 Centralbl. 1891. 



J " Untersuchungen iiber mikroskopische Schiiunie und das Proto- 

 plasma." 



