TRANSACTIONS OP SECTION K. 777 



CJlSes the foliage of the rest of the tree was silvered. On one of the red-currant 

 bushes recently seeu to be silvered the fruit bodies of this fungus were found 

 to be growing. So far, the sporophores of Stereum have been found only on 

 dead branches ; upon cutting sections of these parts, hyphac arc found to be 

 abundantly present in the vessels of the wood. No mycelium has yet been 

 found in the portions of the silvered tree which are still living. 



Certain inoculation experiments have been performed. In previous work on 

 tliis disease all these experiments, as far as I am aware, have been made with 

 pieces of the sporophores of Stereum. It was decided, therefore, to make a 

 number of inoculations with clean spores, as well as a series of inoculations 

 with sporophores. 



Upon placing pieces of sporophore in the branches of healthy trees, the 

 foliage beyond the point of inoculation became silvered a few months later. 

 These results are identical with those of Percival and Pickering. 



On the other hand, the spore inoculations have not yet resulted in causing 

 the foliage to become silvered, although certain of these experiments were 

 made more than a year ago. It is not likely that the germinative capacity 

 of these spores was at fault because the spores have been found to germinate 

 well in hanging-drop cultures of plum-wood extract. It is possible that the 

 silvered effect may appear next season after the mycelium arising from the 

 spores used in these inoculations has developed more luxuriantly. However, 

 it is conceivable that the factor in the sporophore inoculations which causes 

 silvering of the foliage to ensue may be absent from the spore inoculations. 



In the course of this work it has been found possible to grow the mycelium 

 of Stereum purpureum in pure culture. By sowing the spores on blocks of 

 sterilised plum wood placed in suitable tubes, a good growth of mycelium has 

 been obtained. It is proposed to use this mycelium in subsequent inoculation 

 experiments. Derived as it is from pure cultures, none of the objections can 

 be raised against the use of this mycelium that may possibly be urged against 

 the employment of pieces of sporophores obtained from branches of diseased 

 trees. 



6. An Arrangement for using the Wafer Blades of Safety Razors in the 

 Microtome. By B. H. Bentley, M.A. 



FRIDAY, SEPT CM BEE 2. 

 Joint Meeting with Section D. — See p. G28. 



The following Papers were read in Section K : — 



1. Vegetative Mitosis in the Bean. 

 By Miss H. C. I. FrasEr, D.Sc, and John Snell. 



In the cource of an investigation of the nuclei of the root apex of Vicin 

 faba it was observed that in the late telophase the chromosomes become attached 

 laterally one to another. At the same time each chromosome was seen, especially 

 in the region of these attachments, to be longitudinally split into two portions ; 

 the fission, widening more or less, was observed to persist throughout the so- 

 called resting stages of the nucleus. Such an appearance of duplication has been 

 recorded by various authors, and has been constantly explained as due to the 

 approximation of paternal and maternal spiremes. 



To obviate confusion from this source the study of gametophytic nuclei was 

 undertaken, and it was found that in the mitotic divisions in the pollen grain 

 duplication of the chromosomes first appears in the late telophase; the formation 

 of a reticulum is due to the lateral attachment and consequent pulling apart in 

 places of the longitudinally split halves. On tho formation of the spireme the 

 lateral connections break down and the split halves become more or less closely 



