NOTES AND ABSTRACTS. 



411 



Radish, Wild and Cultivated. By Y. Thouard-Riolle (Rev. Hort. vol. xci. pp. 

 244-246 ; 3 figs.)- — There is no evidence that the cultivated radish is descended 

 from the wild radish, Raphanus raphanistrum. The so-called improved wild 

 radish is a hybrid of R. raphanistrum and the edible radish oi the 

 garden. — S. E. W. 



Raspberries. By H. F. Maxim (U.S.A. Dep. Agr., Ball, iii., vol. xvii. pp. 

 14-20). — Three types of Raspberries are grown in the States, Rubus strigosus (red), 

 R. occidentalis (black), and R. neglectus (purple). The best- known native varieties 

 of the red raspberry are ' Cuthbert ' and ' Golden Queen.' ' St. Regis 1 is the 

 most valuable form of perpetual-bearing raspberry. ' Cumberland ' and ' Gregg ' 

 are the best black raspberries. The purple is a hybrid between the red and the 

 black. Like the latter it is propagated by bending down the canes into the soil 

 where the tips root. — 5. E. W. 



Ravenelia, Notes on New or Rare Species of. By W. H. Long (Bot. Gax. 

 vol. lxiv. No. 1, July 191 7 ; pp. 57-69). — Three new species are described — viz. 

 R. Hoffmanseggiae, found on Cassiaceae ; R. siderocarpi and R. prosopidis on 

 Mimosaceae. These fungi were collected by the author while on field work in 

 Texas.— R. J. L. 



Resin Secretion in Balsamorrhiza sagittata. By E. C. Faust (Bot. Gaz. 

 vol. lxiv. No. 6, Dec. 1917 ; pp. 441-479; 4 plates). — Resin is a by-product, 

 formed as the result of the metabolic activities of the plant. During growth 

 a polysaccharide, inulin, produced during photosynthesis, is broken down, causing 

 a by-product, balsamoresene, to be produced. This resene is changed to resinic 

 acid. On account of the probable toxic nature of the resene and resinic acid 

 to the plant, they are translocated (largely in the form of balsamoresene) to 

 schizogenously formed ducts of endodermal origin. Since resene and resinic 

 acid are toxic, they may be used as a guard against mechanical and parasitic 

 injury. — R. J. L. 



Respiration : Effect of Anaesthetics upon Respiration. By A. R. C. Haas 

 (Bot. Gaz. vol. lxvii. No. 5, May 1919, pp. 377-404 ; with 7 graphs). — The 

 writer found that " when Laminaria is exposed to anaesthetics (in sufficiently 

 high concentration to produce any result) the initial effect is an increase of 

 respiration. This may be followed by a decrease if the anaesthetic is sufficiently 

 toxic. No decrease of respiration is observed when the concentration is too 

 low to be toxic." — R. J. L. 



Rhododendron campy locarpum. By S. Mottet (Rev. Hort. vol. xci. pp.. 328. 

 329 ; 1 fig.). — Interesting results may be expected from the hybridization of 

 other Rhododendrons by the yellow-flowered R. campylocarpum from Sikkim. 



5. E. W. 



Root-Rot of Tobacco, Influence of Soil on. By J. Johnson and R. E. Hartman 

 (Jour. Agr. Res. vol. xvii. No. 2, May 1919, pp. 41-86, 8 plates). — The 

 root rot disease of tobacco caused by Thielavia basicola is characterized by 

 stunting of the plants, due largely to a reduced root system. This is in turn 

 due to soil environment. From the experiments made, it appears that there 

 is no variation in pathogenicity of the root-rot fungus from different sources. 

 The amount of the disease is determined by the susceptibility of the host, the 

 amount of infection, and the soil factors. Root-rot is capable of developing in 

 relatively dry soils, for increasing the moisture content of the soil up to three- 

 fourths of its water holding capacity does not materially increase the disease. 

 Saturated soils are more favourable, however, for the disease than unsaturated 

 ones. The most favourable temperature for the disease is from 17° to 23 0 C. 

 Below and above this range practically no infection occurs. The disease is 

 checked by acid soils, while a high organic matter content no doubt favours 

 infection, and also serves as a host for the fungus. Clay seems to favour the 

 persistence of the parasite in the soil, and may favour infection. 



A short bibliography is appended. — A. B. 



Root Systems : Development of Root Systems under Dune Conditions. By 



W. G. Waterman (Bot. Gaz. vol. lxviii.,No. 1, July 1919, pp. 22-53; wi tn l 7 

 figures). — The writer concludes that, " giving due weight to the possibility 

 of moisture, oxygen content, and penetrability of the sand as influencing factors, 

 the evidence seems to point conclusively to nutrient or at least chemical influence 

 as the cause of variability in symmetry in the extension of roots under dune 

 conditions." Dune soil contains not only old soil layers but minute streaks and 



VOL. XLV. 



2 E 



