



512 , MU. S. J<E M. MOOBK'S STUDIES 



and this even after the lapse of 30 hours, long before which time 

 the callus had all been dissolved away. However, it was deemed 

 advisable to continue the experiment for some time longer ; but 

 inasmuch as, after 60 hours, the action of the fluid was still 

 resisted, we can hardly err in coming to the conclusion that the 

 stoppers are not attacked by a peptonizing fluid. Plate XIV. 

 fig. 7 shows a pair of stoppers still unaffected after 30 hours' 

 action of the fluid. 



Peoteid Eeactions of the Stoppees. 



We 



hence particular care is necessary in drawing conclusions as to 

 their proteid nature. Our chief guide in this matter will be 



f 



similarity in 

 the cell *. 



It will be necessary also to attend in some detail to the 

 reactions of the cell-wall. Before entering on the task, however 



— v „ v _ „ v — & , 



I may say that the stoppers, both here and in other Floridea) m 

 which they have been studied, have generally been considered as 

 being of proteid, if not of protoplasmic nature t- 



Xanthoproteic reaction. — This is very well given indeed ; as 



Marrow 



of ammonia if the reaction is to come off properly (fig- 5 )- 

 The same colour, only somewhat paler, is given by the cell- 

 protoplasm. Preparations treated in this way preserve their 

 colours perfectly in glycerine. 



Mil I on 



the 



. 



h the portion of the pit-protoplas 

 well differentiated/' 





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. 







i 







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J 



J^H< 



stoppers, but if boiliDg be continued above a second or two, the 

 colour flies ; it is best got at temperatures a little below boiling. 

 The cell-protoplasm almost always takes a much paler colour, 

 but where the contents are densely aggregated, as so often 

 occurs in the neighbourhood of the stoppers, I have sometimes 

 seen a colour almost, if not quite, as deep as that assumed by the 

 stoppers. Comparison of figs. 2 and 4 will show the different 

 ways in which Vegetable-Marrow callus and the stoppers react to 



This point is insisted on by Fischer in his paper on proteid reactions of 

 the cell-wall (Ber. d. deutsch. hot. Gesellsch. 1887, p. 426). j 



t Thus Gardiner (Proc. Camb. Phil. Soc. 1884, p. 106) says, apropos of the 



I 













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