814 REPORT—1904. 
2. Struggle for Pre-eminence and Inhibitory Stimuli in Plants. 
By Professor L. Errera. 
Vegetable physiology, like animal physiology, presents a great number of cases 
of suspensory stimuli, or inhibitory phenomena: arrest of growth of the fructiferous 
filament of Phycomyces during the formation of the sporangium ; influence of 
wounds on the growth, and irritability of certain organs (traumatic shock) ; 
retarding effect of light on elongation, &c. It is also in this way that the influ- 
ence exercised by the apex of many plants on the subjacent ramifications with 
which it finds itself in some way struggling for pre-eminence can best be understood. 
The apex of Picea excelsa, for instance, hinders the side-branches from rising 
geotropically. If one suppresses it, or if it is notably weakened, a conflict for 
supremacy obtains between the branches themselves; generally one of the branches 
nearest the summit, or the strongest among equidistant ones, prevails and forms 
a new summit. The apex continues to make itself felt even after the removal of 
a ring of bark; its action then probably proceeds through the living cells of the 
pith and the medullary rays. On the other hand, in the Arauwcarias (where the 
regeneration of the summit is effected hy new buds, and not by the rising of 
already developed branches) the action of the apex is conducted by the bark, 
and an annular incision is equivalent to cutting off the top. 
Several arguments can be quoted to support the existence of inhibitory stimuli 
emanating from the apex, and the production of ‘suckers’ (gourmands) and of 
‘witches’ brooms’ can be connected with it. 
3. On the Proteases of Plants. 
By Professor 8. H. Vinks, 7.2.5. 
As the result of observations made in the course of the last three years, of 
which accounts have been published from time to time in the ‘ Annals of Botany,’ 
I have demonstrated the very general occurrence of proteases in all parts of 
lants. 
c With regard to the nature of the proteases, it has been ascertained, in the first 
place by means of the tryptophane-reaction, that their action is peptolytic—that 
is, that they decompose peptones and albumoses into non-proteid substances such 
as leucin, tyrosin, and other amido-acids. In no case was peptonisation observed 
without peptolysis; whence it follows that the proteases are not of the nature of 
pepsin, but rather correspond to either the trypsin or the erepsin of the animal 
body. 
It has been found that in certain cases the juices or extracts of plants can 
peptonise fibrin, indicating the presence of a tryptic protease; but more com- 
monly they do not possess this capacity, The following are instances of the 
peptonisation of fibrin :— 
Pine-apple (juice); papain (solution); nepenthes (pitcher-liquid); yeast 
(extract); mushroom (extract); cucumber (juice) ; melon (juice); wheat-germ 
(extract); asparagus (juice); Phytolacca decandra (extract of leaves); fig 
(extract of leaves). 
It may be inferred that a tryptic protease is present in these plants. 
It is not necessary to give a list of cases in which peptolysis of albumoses and 
peptones (as contained in the commercial preparation known as Witte-peptone) 
has been observed; it appears that the juice or watery extract of almost any 
part of any plant can effect this process. Although fibrin is not digested in these 
cases, yet any proteid matter naturally present in the juice or extract is digested 
(autolysis). Hence it may be inferred that an ereptic protease is present. 
I have found in the yeast and the mushroom that both a tryptic and an 
ereptic protease are present; no doubt other cases of such an association of 
proteases, analogous to that of the ‘trypsin’ of animals, remain to be discovered. 
It may be stated generally that these proteases are most active at the natural 
degree of acidity of the juices or extracts, 
