6 Ph5'^siologie. 



tinuity in the shooting of new foliage, it appeared that the majority 

 shoot in the driest months, February and December. 



It is suggested that in such a humid climate it may be only in 

 the dry periods that transpiration is active enough to raise an ade- 

 quate supply of the mineral matters required for the new growth 

 of foliage. If this is so then the red colour of young foliage will be 

 of assistance at the critical time. J. J. Blackman. 



Thoday, D. and M. G. Sykes. Preliminary observations on 

 the Transpiration Current in submerged Water-plants. 

 (Ann. of Bot. XXIII. p. 635—637. 1909.) 



The authors have noted and measured the rapid rate at which 

 submerged healthy shoots of Potainogeton suck up eosin when the 

 cut end of a branch is inserted into a vessel of eosin Solution. The 

 dye may ascend even to the distance of 19 cms up the stem in two 

 minutes. The conditions on which this depends have yet to be in- 

 vestigated but it is clearly largely due to the leaves, for their removal 

 nearly stops it. The flow may take place in the reverse direction 

 when the cut tip of the stem is placed in eosin but the rate of 

 movement is then much reduced. • J. J. Blackman. 



Vines, S. H., The Proteases of Plants. VI. (Ann. of Bot. XXIII. 

 p. 1—18. 1909.) 



This further communication records the complete Separation of 

 peptase and ereptase in the case of Papain and of Yeast. The pro- 

 cedure previously successful with Hemp seed was not applicable to 

 material poor in proteids and a rather different method of Separation 

 was developed. 



An extract which peptonises without peptolysing can be prepared 

 from crude papain (dried latex of Carica Papaya) by filtering the 

 5% NaCl extract into alcohol and extracting the bulk}?- precipitate 

 with 20/o NaCl after all the erepsin (and some of the pepsin) has 

 been washed away with distilled water. 



A peptonising extract from fresh Saccharotnyces cerevisiae can 

 be obtained by allowing washed yeast to stand for some time with 

 chloroformwater, filtering the extract into alcohol and then procee- 

 ding as with papain. 



The latter part of the paper contains a historical account of the 

 course of the author's work which has established the Separation of 

 plant proteases into two classes peptases and ereptases. 



The characters of these are here summarised. Ereptases solu- 

 ble in water, dilute saline Solutions, and alcohol up to 650/o have no 

 power of acting upon the higher proteins but are exclusively pepto- 

 lytic and are associated with an acid medium. These hardl}^ differ 

 from the erepsin discovered by Cohnheim in the alimentary canal 

 of animals. 



Peptases fall into two sub-classes. Their activity is limited to 

 hydrolysis of the higher proteins as far as peptone, the digestion 

 never being carried to the stage of tryptophane. [It will be noted 

 that Vines does not adopt the modern Conventions for the nomen- 

 clature of enzymes by which a 'peptase' should be an enzyme that 

 hydrolyses 'peptones']. 



Of these sub-classes the Ectopeptases are represented by the 

 enzyme of Nepenthes pitcher which acts well with free HCl just like 



