466 Dr. A. J. Ewart. On the Physics and Physiology 



These results also accord with the appearance of the plants them- 

 selves. The want of Po0 5 results in a long limp growth, and very 

 pale colour, and the attacked spots show corrosion and collapse instead 

 of normal flecks. 



Similarly, in plants deprived of K we have pale collapsing patches 

 in place of normal flecks, though the plant is not drawn and etiolated 

 as in the previous case. Where Mg was wanting the drawing and 

 paleness of the leaves were not so marked, and the fungus flecks in 

 the positive case were more like the normal. 



That a want of supplied Ca should have very little effect on either 

 host or parasite, was no doubt due to there being small quantities 

 available in the soil and pots. The flecks and pustules were apparently 

 normal, though small. 



It is not easy to see why the pots with water only yielded plants 

 with flecks as good as, or even better than those with normal solution, 

 unless the concentration of the salts affects the fungus. However it 

 is probably not to be inferred that in any of these cultures the grass 

 was totally deprived of the given salt it would get traces from the 

 pots and coir in any case but the effects of deprivation of salts ought 

 certainly to be felt, and I think were so to some extent in lengthening 

 the incubation period. 



So far as the results go they suggest that differences in the supply 

 of minerals affects the development of mycelium and of spores owing 

 to effect on the host in cultivating the host we also cultivate the 

 parasite. 



But I would insist that these trials with special mineral-supplies 

 are merely preliminary. The task in hand was far too extensive for 

 the problems to be solved in one season, and I contemplate carrying 

 the whole matter or persuading some one to do so much farther 

 in the future. Meanwhile, the results give suggestions for further 

 work, and much remains to be done along the lines I have here laid 

 down, as well as in directions yet to be opened out. 



" On the Physics and Physiology of the Protoplasmic Streaming 

 in Plants." By ALFKED J. EWAET, B.Sc. (Oxon.), D.Sc. (Lond.), 

 Ph.D., F.L.S., Lecturer on Botany in the Birmingham Techni- 

 cal Institute. Communicated by FRANCIS GrOTCH, D.Sc., F.R.S. 

 Received January 17, Eead February 20, 1902. 



(Abstract.) 



The results of an extended series of observations upon this phe- 

 nomenon have led the author to conclusions which may be summarised 

 as follows : 



