loo BOTANICAL GAZETTE [July 



If this be true, it is probably the only case on record where the actively dividing 

 members of a meristem act as nurse cells. 



One of the most striking experimental results Isaburo-Nagai publishes 



concerns 



While 



unable to duplicate the results of Heilbronn 27 in inducing adventive branching 

 by exposing the prothallia to such narcotics as ether and chloroform, he finds 

 that plasmolysis of the cells of the gametophyte will induce luxuriant forma- 

 tion of the vegetative shoots. In his explanation of this fact he makes the 

 statement that the stimulus of plasmolysis is a purely physical one, consisting 

 probably of the withdrawal of water from the cell. The possibility of this 

 stimulus being chemical in its nature is precluded, because plasmolytic agents 

 of widely different chemical nature all produce the same effect. He believes, 

 also, that this is not a traumatic response, since wounding the thallus with 

 a fine needle will not produce or stimulate the production of adventive branches. 

 He accepts as a solution of the question the explanation of Klebs who claims 

 that the normal cell growth, at first rapid, is checked by the formation in the 

 cell sap of deleterious substances. These are either withdrawn in the plas- 



allow 



normal 



by the concentration of the cell sap during plasmolysis. A further hypothesis 

 is that the growth of the older cells is checked by the younger cells through the 

 direct protoplasmic connections between the tw T o; that plasmolysis ruptures 

 these connections; and that, therefore, upon the return to the normal condition 

 vigorous growth may be resumed. 



The investigation is concluded with a few additional facts on the influence 

 of light upon germination, which are of no particular significance, inasmuch as 

 they merely add a few names each to the lists of those spores which can germi- 

 nate in darkness, and those which cannot. — Hermann B. Deutsch. 



2 ? Heilbronn, A., Apogamie, Bastardierung, und Erblichkeitsverhaltnisse bei 

 einigen Farnen. Flora 101:1-42. 1910. 



