9° 



botanical gazette. f March 





In the part of Hooker's Icones Plantmum, just published, is a descrip- 

 tion of a gigantic ice-plant of S. Africa, whose kk Jeaves are bo juicy that it 

 not only furnishes the cattle with moisture in that country, but is used by 

 Europeans in traveling for the purpose of washing, and even drinking, 

 the water squeezed out being devoid of taste." (Gaul. Chron., Jan. 19.) 



M. Buysman, of Middelburg, Holland, whose preparation of analytical 

 herbaria we have already noticed (Bot. Gazette, xiii. 326), in a private 

 letter calls attention to a change in the mode of preparation by his col- 

 laborators. The necessary fragments and flowers are not to be sent in 

 bottles, as previously mentioned, but in tin boxes thoroughly moistened 

 with alcohol. This change has been suggested by Dr. Schweinfurth. 

 The tin boxes, and alcohol if necessary, will be furnished by M. Buysman 

 to all who desire to help him. Only the colored flowers he wants dried 

 and spread out. The aid of American botanists is asked in supplying the 

 medicinal and useful plants (cultivated or not) of this country. All neces- 

 sary expenses are to be paid by M. Buysman, to whom application may 

 be made for fuller information. 



Bokorny has recently confirmed to some extent Bayer's theory of as- 

 similation, viz.: that green plants in light reduce C0 2 , CO remaining 

 loosely combined with thechlorophyll,and from this some simple substance 

 (such as formic aldehyde, CHjO) is first formed, which is subsequently 

 converted into a carbohydrate. Experimenting with Spirogyra, he ex- 

 cluded C0 2 and furnished instead formic aldehyde, methylal, methyl al- 

 cohol, glycol, or glycerin. Formic aldehyde proved poisonous, but from 

 all the other substances the plants were able to* manufacture starch and 

 increase their dry weight. That they are able to convert these substances 

 into a carbohydrate is not demonstrative evidence that they actually form 

 these substances in the course of manufacture of carbohydrates from C0 3 , 

 but it increases the probability that they do. 



Wiesner, in a preliminary paper in the Bot. Zeitung (1889, nos. 1,2), 

 undertakes toshow that the older parts of plants by their transpiration draw 

 on the water supply of the younger and that this affects greatly the devel- 

 opment of these parts. The water so sucked away from the upper parts 

 he speaks of as " the descending water stream." En general the buds, ax- 

 illary and terminal, as well as the shoots arising therefrom, are hindered 

 more or less completely in their development by rapid transpiration and 

 iccelerate.] by slower. By thus affecting the development of growing 

 points, it is the transpiration and not the innate constitution of the plant 

 which determines the production of sympodial shoots, or of false dichot- 

 omy. This his experimental evidence seems to confirm, since he w r as 

 able to cause the abortion or development of the terminal bud by regula- 

 ting the transpiration. The effect of transpiration is of course not direct 

 It acts by altering the turgor of the cells, the plasticity of the cell-wall, 

 and possibly the structure of the protoplasm in the growing points. 



