Prof. H. Mohl 071 the Latex and its Movements » 443 



Schultz, independent of external influences; Prof. Mohl states 

 that the latex in its natural condition is in a state of absolute 

 repose. By bringing portions of uninjured plants of Chelidonium 

 beneath the microscope, he found that while the connexion be- 

 tween the leaf under examination and the rest of the plant was 

 unbroken, a current could generally be perceived which lasted for 

 about half a minute and then gradually ceased ; he satisfied him- 

 self that this was produced by the torsion and compression of the 

 vessels of the neighbouring parts. When the petiole was cut 

 across, a very rapid current took place towards the wound, which 

 continued until the coagulation of the extravasated latex closed 

 the wounded vessels. On cutting a little further up, the current 

 was set up again. In the leaves of Tragopogon mutabilis, where 

 the principal nerves take a rectilinear direction, the current could 

 be made to flow from the summit to the base, or from the base 

 to the summit of the leaf, according as the apex or the petiole of 

 the leaf was cut ofi*. The slightest pressure, also, afi'ected the 

 direction of the current. 



The author denies also that the rotation in the cells of Tra- 

 descantia, &c. takes place in delicate vessels situated on the walls 

 of the cells, as indicated by M. Schultz ; since no such vessels 

 can be traced, and the size and position of the currents are fre- 

 quently seen to change in a manner which the idea of the con- 

 traction and dilatation of such vessels is insufficient to explain. 



3. Of the Latex as the Vital Juice, 



M. Schultz compares the latex to the blood of animals, not 

 only as regards its internal organization and its movements, but 

 as regards its physiological value, declaring it to be the nutrient 

 fluid of plants. 



Prof. Mohl says, that if he has succeeded in proving " that the 

 latex does not possess the internal organization which M. Schultz 

 attributes to it ; that it difiers in no particular, as far as regards 

 its globules, from other vegetable juices which contain substances 

 insoluble in water, such as oils, resin, or starch ; that M. Schultz^s 

 theory of the coagulation is based upon false observation, and 

 that the latex in uninjured plants exhibits no movement '^ — he 

 might abstain from further detail, convinced that all unprejudiced 

 observers would arrive at the same conclusions : if these observa- 

 tions are confirmed by others, it will necessarily be seen that 

 those very points on which M. Schultz founded his theory, and 

 which alone have determined him in establishing his doctrine, 

 are founded on illusions. 



In addition to erroneous observation, however, M. Schultz's 

 theory is supported by the application of an analogy which he 

 has established between plants and animals. He concludes, that 



2G2 



