AGRICULTURAL BOTANY. 627 



value as a means of iucreasiug germiuabilily. Scratcliiug the seed coats with 

 powdered glass or emery, while helpful, does not pi'oduce so good results as does 

 treatment with hydrogen peroxld, which was of material benefit, the effect 

 i-eacliing the maxiniuiu at GO per cent strength of the solution when applied to 

 the seeds for not over IS to 24 hours. 



Pollen development in the grape with special reference to sterility, M. J. 

 DoRSKY (Minnesota Sta. Bui. UfJi (191Jf), pp. GO, pis. Jf). — A report is given of 

 an investigation conducted to determine the cause of sterility in grapes and 

 whether it can be controlled. As a basis of the investigation studies were made 

 of the variety Brighton, which is said to be typical of a number of sterile or 

 nearly sterile cultivated varieties of grapes. Comparisons are also made with 

 the parent varieties frou) which Brighton was derived, as well as a number of 

 other species and varuMies. 



The factors bearing ui>on the i)henomenon of sterility were found capable of 

 being divided into two classes, those inherent to the plant and those resulting 

 from an unfavorable environment. In the grape the inherent cause of sterility 

 was found to be due to the pollen rather than the pistil. Cytological studies of 

 the pollen showed that sterile pollen in the grape results from degeneration 

 processes in the generative nucleus or arrested development previous to mitosis 

 in the microspore nucleus. Aborted pollen is found in varying quantities with 

 both sterile and fertile pollen. It occurs in pure forms as well as in hybrids, 

 but is usually moi'e abundant in the latter. Since pollen is produced in abun- 

 dance by the grape, aborted pollen is relatively unimportant from the stand- 

 point of fertilization or the setting of fruit. 



As a practical deduction from his investigations, the author states that as 

 both fertile and sterile hybrids occur among the cultivated varieties of Amer- 

 ican grapes, hybridity is not necessarily a cause of sterility. It is evident that 

 the cause of sterility in the grape is deep-seated and intimately connected with 

 the functional activity of ix»llen. and can not be overcome by cultural condi- 

 tions, but will have to be avoided by mixing varieties in the vineyard at plant- 

 ing time. 



A bibliography is given. 



Injury and abscission in Impatiens sultani, F. E. Lloyd (Ann. Rpt. Quebec 

 Soc. Protec. Plants [etc.], 6 (1913-14), PP- 72-79, figs. 11).— After noting con- 

 tributions by others, the author gives results of his own studies with /. svltani. 



Injury does not seem to cause abscission. The abscission layer lies just 

 above the base of the internodes, but it is not strictly limited to any particular 

 position, the ixiint of its occurrence being determined physiologically. There 

 is no special abscission tissne, the immediate cause of abscission being, it is 

 claimed, the hydrolysis of the middle lamella, no disintegration of tissues occur- 

 ring in any other sense. Increased turgor is claimed to play no part in this 

 connection. 



Some relations of plants to distilled water and certain dilute toxic solu- 

 tions, M. C. Merrill (Ahs. in Krienee. n. ser., J,l (1915), No. IO4S, p. 176).— A de- 

 termination was made of the interval during which pea seedlings could be left 

 in redistilled water and in certain toxic solutions and then recover when later 

 placed in a full nutrient solution. Horse beans (Yicia faba) were more 

 marked than pea seedlings in their behavior toward the renewal of distilled 

 v,-ater. those in which the distilled water was renewed showing more than 

 double the growth. Bacterial and fungus action was found to be undoubtedly 

 ;in important factor, and the evidence obtained indicates that there are several 

 factors entei'iug into the so-called harmful action of distilled water. 



