













% 





502 



Mil. S. LE M. MOORE* S STUDIES 











































published an elaborate monograph on the sieve-tubes of Vitis vini- 

 fera 9 Oucurbita Pejpo, and Lagenaria vulgaris ; in this Wilhelui 

 expresses his conviction that callus is altered cell-wall ; and this 

 view was acquiesced in by Janczewski * shortly afterwards. In 

 1882 we find the opposite idea broached by Russow f , who takes 

 his stand upon the ground of the difficulty of reconciling the 

 disappearance of callus in spring-time with clearing of the sieve- 

 piates, that is, their return to the primitive condition — the 

 difficulty of reconciling this with the origin of callus by swelling- 

 up of the wall of the sieve, which ought, if the older view be 

 correct, to show at least some signs of waste in consequence. It 

 is true that Janczewski looked upon the process as one of hydra- 

 tion — the callus swelling up in autumn, a time when the watery 

 reserves in the plant tend to increase, and condensing and con- 

 tracting by loss of water on the return of spring. But this is 

 obviously unsatisfactory; for it may be remarked that were this 

 idea correct, we ought to find callus diminishing in quantity pro- 

 portionally to the withdrawal of water from the plant, and callus 

 ought not to make its reappearance until quite late in the year. 

 Russow ends a strong argument by remarking that all difficulties 

 will vanish if it be admitted that callus consists of contents of the 

 eieve-tube deposited upon the sieve-plate. 



Strasburger % came to Russow's support in 1884 ; and in the 

 same and also following year Gardiner § declared himself upon 

 the same side : his example was followed by Fischer in 1886 1|. 



On the other hand, we find F. W. Oliver % in 1887, reverting 

 to the older view, his conclusions being founded on careful study 

 of the remarkable deposits of callus in Macrocystis and Nereo- 

 cgstis. Finally, Lecomte ** has expressed himself in the same 

 sense. 



* Mem. de la Soc. des Sc. Nat, et Math, de Cherbourg, t. xxxii. 1881. (Also 

 an extended extract of this in Ann. Sc. Nat. Bot. 6 se>. t. xiv.) 



t Sitzb. der Dorpat. naturforsch. Gesellsch. 1882. Translated in Ann, Sc. 

 Nat. Bot. 6 ser. t. xiv. This was the idea of Hanstein (Milchsaftgefasse). 



J 'Bot. Practician,' ed. 1 (1884). 



§ Proc. Camb. Phil. Soc. 1884, p. 102 ; ibid, 1885, p. 230. 

 Ber.d. deutsch.bot Gesellsch. 1885, and Ber. iib. d. Verhandl. d. k. sachs. 

 GeaelL d. Wise, zu Leipzig, 1886 ; abstract in Bot. Zeitung, 1886, and in Journ. 

 It. Micros. Soc. (same year). 



T Ann. of Bot. vol. i. 









Bot. de France, t. xxxv 





(1889) 

























' 









■ 









■ 









■ 











-J 



















































■ 









