IX VEGETABLE BIOLOGY. 233 



Havin 



if the Vegetable-Mt 



membering that the substance staining like callus discovered by 

 F. "W. Oliver in the trumpet-hyphae of Macrocystis pyrifera, Ag., 

 refuses to give proteid reactions and to peptonize*, re-exami- 

 nation of the Vegetable-Marrow seemed desirable. But very- 

 little progress had been made, when I found that I had been 

 unfortunate in basing my conclusions with regard to Vegetable- 

 Marrow callus upon observations which, although perfectly 

 correct in themselves, were yet in a measure valueless, from 

 having been made with abnormal material. I have preserved 

 two sections derived from that material, each of them showing 

 a considerable number of sieves all cleared after the action of 

 a peptonizing fluid, and without the slightest suspicion of callus 

 anywhere ; and this is an obviously abnormal occurrence, in 

 view of the undoubted fact that the true callus of the Vegetable- 

 Marrow will not peptonize and will not give proteid reactions. 

 In fact, it behaves in the latter respect just as does the callus 

 of the Fig and of Macrocystis, either swelling up almost to 

 invisibility, or dissolving with great promptitude. The state- 

 ments made in the former memoir must therefore be understood 

 as applying not to the true callus, but to the proteid callus, 

 *. e. the paracallus ; and I believe the latter substance to occur 

 much more frequently in the Vegetable-Marrow than the former, 

 at least that is the inference suggested from the material at my 

 command. 



Concerning this paracallus, a few more facts have been made 

 out. In the former memoir its affinity with coagulated proteid 

 was suggested, and this seems borne out by its behaviour with 

 nickel sulphate and ammonia. This is G-nezdas t test for proteids; 

 albuminates, globulins, fibrin, and mucin giving a pale-blue solu- 

 tion with it, while coagulated proteid is turned yellow. 



Now if sections of Vegetable- Marrow bast be allowed to lie 

 in G-nezda's fluid, the paracallus-masses will be found to be bright 

 yellow, a colour which becomes somewhat more pronounced on 

 running in caustic potash ; and this, according to Gnezda, is a 

 further peculiarity of coagulated proteids J. Another matter 



As was Bhown in my former memoir on callus (Journ. Linn. Soc., Bot. 

 T °l. xxvii. p. 519). f Proc. Eoy. Soc. vol. xlrii (1890). 



I In one case a distinct blue colour was taken by a paracallus-mass; perhaps 

 his indicates a mixture of proteids in paracallus. 



IIW ' JOUBJf. — BOTANY. VOL. XXIX. T 



