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IN VEGETABLE BIOLOGF 



519 























case and ineffectiveness of anxiolytic might explain this, or better, 



perhaps, the low temperature of the time of leaf-fall. And if 



there be a eallolytic ferment in the tubes, it is easy to understand 



how, when the cool weather of autumn sets in, it would cease to 



be effective, and callus would then make its appearance upon the 

 sieves *. 



Considerations such as these led me to search for a proteolytic 

 ferment in the sieve-tubes of the Lime-tree. I tried the method 

 of Baranetzky as well as that of Von Grorup-Besauez, but in neither 

 case with success. This is scarcely to be wondered at when it is 

 understood how very small must be the quantity of callus, and 

 hence of ferment necessary for its dissolution, even in an entire 

 tree. Perhaps I did not choose a very favourable subject ; and 



the Hop or Phragmites communis might answer the purpose 

 better. 















































































w 



r Macrocystis pyrifera, Ag. 



Discovered in 1881 by Jeffrey Parker t and studied by Will i, 



, the sieve-tubes and trumpet-hyph© 



W 





of Macrocystis and Nereocy 



Laminaria, have been found with their contents in undoubted 

 communication. Oliver has made the interesting discovery of a 

 substance giving the ordinary reactions of callus in the sieve- 

 tubes and trumpet-hyphas of Macrocystis and Nereocystis % and 

 he has adduced evidence which leaves but slight doubt, if auy at 

 all, that the callus at least of the trumpet-hyphaj is formed by 

 swelling-up of the cell-wall. I have made many experiments 

 with Macrocystis pyrifera, and in no case has the slightest trace 

 of proteid reaction been observed ; indeed the xanthoproteic is 

 out of the question, for the callus rapidly dissolves in warm nitric 



* Sachs (Bot. Zeitung, 1802) finds the contents of the sieve-tubes to be 

 alkaline ; hence one would suppose that normal callus-digestion, if it really 

 occurs, is of pancreatic, not of gastric nature, unless, indeed, temporary acidity 

 make its appearance when the sieves reopen. 



t Trans. N. Zealand Inst. 1881, p. 562. 



t Bot. Zeitung, 1884. 



§ Kongl. Svenska Vet-Akad. Handling, xxi, and Ber. d. deutech. bot. Gesell. 

 1885. 



Ann. of Bot. vol. i. . 



IT Hick(Joum. Bot. 1886) has described continuity between the protoplasts 

 of some Fucace*. It would be interesting to know if callus is developed in these 

 cases. 





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