ECONOMIC ZOOLOGY ENTOMOLOGY. 755 



Branch cankers of rhododendron, II. von Schrenk {Mo. Hot. flnnl. Ann. 

 Rpt., 18 in)()7). 77-80, /)/.s. 2, flg. Z).— The author reports havins noticed for sev- 

 eral years peculiar canker-like growths on the branches of Rhododendron ma.i-i- 

 niiiin. These cankers appear in the form of large swellings of peculiar shape, 

 and a large shrub may have anywhere from 1 to 40 or 50 cankers, sometimes 2 or 

 o occurring on one branch. The parts of the branch above and below the canker 

 ai) )ear normal, and the canker does not seem to intlncncc^ materially the growth 

 or development of the branch upon which it is situated. It appears to be simply 

 a localized swelling which does not exert any influence upon the branch. 



A careful examination showed that the cankers always originate arountl a 

 small dead branch and that they arc iirimarily due to an attempt on the part of 

 the branch to heal over a dead stub. When a lateral branch dies the wood of 

 the parent branch or trunk begins developing a healing layer at a considerable 

 distance from the base of the dead branch. The rate of growth on the rhodo- 

 dendi'on is very slow, and consequently it requires a long time to completely heal 

 over a wound. On account of this slow growth the callous lips increase from 

 year to year, giving rise to the knots or swellings which are described. 



This abnormal condition is described to call attention to the fact that patho- 

 logical conditions may arise without direct interference from other living 

 organisms. 



Studies in root parasitism, C. A. Barber {Mvni. Dcpt. Agr. India, Bot. Set:, 

 J {1907), \(t. 1, lit. 2, pp. V+.58, pis. 16). — In continuation of a previous paper 

 (E. S. It.. IS, p. 348) the author gives further results of his studies in root 

 parasitism as exemplified by Santdliini album. Detailed descriptions are pre- 

 sented of the structure and development of the haustoria, methods of attack 

 and penetrati(m. and the inter-relations l)etween the host and its parasite. The 

 piMietration of the host tissues seems to be effected by pressure on the root of 

 the host and by secretions from the haustoria of the parasite. The protection 

 against the parasite is mainly secured by the development by the host of thick 

 walled tissues or cork layers about and in the path of the advancing haustoria. 



On the presence of copper in vineyard soils, O. Prandi {Staz. Spcr. Ai/r. 

 Hal., J,0 {11)07), No. 7-8, pp. JJi-J//'/ ) .—After a review of literature relating to 

 the effect of copper accumulating in soils where spraying has been continuously 

 liracticed for a long time, an account is given of a series of experiments con- 

 ducted to determine the amount of copper present in soils of vineyards where 

 heavy sjiraying with Bordeaux mixture had been practiced. These experiments 

 were begun in 1004 and are to be continued indefinitely. Samples weighing 

 l,(tO() j;ui. were taken of the soil and subsoil as near to the grapevines as possible, 

 and after the removal of all sticks and trash the sample was leached with a 10 

 per cent ammonia solution or with cai-bonated water and the amount of copper 

 in the solutions determined as coi)per oxid. 



The amounts thus far obtained have not been suMicient to cause any injury, 

 iiut on account of the action of very dilute solutions of copper on bacteria, the 

 author thinks that the copper in the soil may have an important bearing on the 

 activity of soil organisms. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Zoology of the Transvaal {The Transvaal and Its Mines. London and 

 Johanncshiinj, J906, pp. D.'i-L^O, flgs. 99). — A descriptive account is given of the 

 numerous game birds and mammals found in the Transvaal, together with a 

 brief account of the reptiles, amphibians, fish, and insects. The zoological 

 gardens at I'retoria are well stocked with a variety of the most important and 



34157— No. S— OS -5 



