NOTES AND ABSTRACTS. 



299 



18 per cent, formed no root hairs, whilst in 66 per cent, the hairs were 

 much, and in 16 per cent, slightly, stunted. 



Similar injurious effects were produced by diluted sea-water, 

 •001 per cent, carbolic, and by tea and coffee and other substances. 

 The toxin is present in bog-water in very small amount, as when half 

 dilution was used all the root hairs were normal. Bacteria were 

 always found in bog-water and peat even from 75 cm. depth. Decay 

 in fresh beef is almost as rapid in peat -water as in tap-water. 



He concludes that there seems to be a toxin in bog-water which 

 disappears with drainage (and after filtering water with filter paper), 

 and that possibly the poisonous effect is due to the reduction of ab- 

 sorptive surface by injury of root hairs. — G. F. S. E. 



Phosphate in Soils, Factors influencing Availability of Rock 



(U.S.A. Exp. Stn., Wisconsin, Bull. 20 ; January 1912). — The 

 experiments carried out demonstrate that organic manures add to the 

 availability of insoluble phosphates ; the chief active agent being the 

 carbon dioxide given off by organic manures and the roots of plants. 

 When the ground phosphate is thoroughly incorporated with the soil, 

 the weight of crop gathered is almost equal to that gained by the 

 addition of acid phosphate. 



Recommends all insoluble phosphates should first be thoroughly 

 mixed in a good proportion of soil and then spread. — G. P. C. 



Phosphates, Effect of Cowdung on the Availability of Ground 



Rock (U.S.A. Exp. Stn., R.I., Bull. 151 ; 1912). — A series of 

 experiments to demonstrate whether the addition of rock phos- 

 phate to the dung would increase the availability of the former. In 

 the end, the results showed nothing worth the extra cost and labour, 

 a mere mixture used immediately giving rather better results than 

 when mixed and allowed to stand over a long period. — G. P. C. 



Phytophthora infestans and the Development of Oospores, On 

 Pure Cultures of. By G. H. Pethybridge and P. A. Murphy 

 (Sci. Proc. Roy. Dublin Soc, vol. xiii., No. 36, pp. 566-588 ; March 

 1913 ; 2 plates). — Recent work has shown that it is possible to grow 

 Phytophthora infestans (the Potato Blight fungus) as a saprophyte, 

 and the authors, after summarizing previous work on the subject, give 

 a full account of the media and method of culture they found to be 

 successful. 



Conidia are very easily procured in artificial cultures, but sexual 

 organs, producing oospores (resting spores), could only be induced 

 to form on two media — namely, Oat-juice Agar and Quaker Oat Agar. 

 On the latter oospores developed plentifully, and the writers were thus 

 able to confirm Clinton's results on the production of these bodies. 



The development of the oogonium follows the remarkable course 

 described by Pethybridge for P. erythroseptica. On Oat-juice agar, 

 however, the oospores develop parthenogenetically, antheridia being 



