i 9 i2] CURRENT LITERATURE 551 



have as a rule been conducted from a laboratory standpoint, and have left 

 unanswered the question of the slow action of these substances under natural 

 conditions. From a study of the effects resulting to vegetation along the 

 tarred roads in some of the parks of Paris, Gatin 22 finds that considerable 

 damage is done to trees and other plants by the tar-laden dust particles; 

 accordingly the injury is less severe along the less frequented roads. A 

 peculiarity of the injury is that it develops very gradually, and in case of the 

 trees did not appear until the practice of surfacing the roads with tar had been 

 continued for two years. Dust collected from tarred roads and dusted at 

 frequent intervals on nursery stock produced characteristic injury, consisting 

 of spotting and browning of the leaves and retardation of growth. — H. 

 Hasselbring. 



Cystidia as hydathodes. — As a result of a critical examination of the 

 cystidia occurring in the hymenium and similar cystidia-like trichomes often 

 found distributed over other surfaces of the fruit bodies of Hymenomycetes, 

 Knolls concludes that, with the exception of certain special types like the 

 large cystidia of some species of Coprinus, these two sets of trichomes belong 

 in a physiological-anatomical sense to the same category of organs, and that 

 they function exclusively as hydathodes. Knoll finds that the exudation of 

 water is restricted to a definite region, with few exceptions, situated at the 

 apex of the trichome. The cell wall at this point is capable of swelling to such 

 an extent that it forms a colloidal solution in the excreted water. That the 

 drops adhering to the ends of the hydathodes consist of a colloidal solution is 

 shown by the gelatinous residue left when the drops are allowed to evaporate 

 on a glass slide, and also by the fact that a membrane is precipitated when the 

 cystidium with the attached drop is immersed in alcohol. Crystals are often 

 deposited on the ends of the hydathodes as a result of evaporation of the liquid. 

 — H. Hasselbring. 



Plant diseases of Texas. — A survey of the plant diseases occurring within 

 a radius of 100 miles of San Antonio, Texas, has been published by Heald and 

 Wolf. 2 * The paper is based on collections made by the writers during a period 

 of about two years, from 1908 to 19 10. It comprises a list of fungi collected 

 on about 200 species of hosts within the region examined, together with brief 

 descriptions of the fungi and notes on the effects produced on the hosts. A 

 number of well executed plates accompany the text; however, the motive that 



22 Gatin, C. L., Die gegen die Abnutzung und den Staub der Strassen angewen- 

 deten Verfahren und ihre Wirkung auf die Vegetation. Zeitschr. Pflanzenkrank. 

 22:193-204. 1912. • 



2 * Knoll, F., Untersuchungen iiber den Bau und die Funktion der Cystidien und 

 verwandter Organe. Jahrb. Wiss. Bot. 50:453-501. figs. 69. 191 2. 



24 Heald, F. D., and Wolf, F. A., A plant disease survey in the vicinity of San 

 Antonio, Texas. Bur. Plant Ind. Bull. 226. pp. 112. figs. 2. pis. 19. 1912. 



