38 Mr. J. W. Swan. Stress and other Effects 



We have shown that the colour was in proportion to the amount 

 of copper present, and that the colourless leucocytes contained 

 only traces of that metal. The deposition of the copper in this 

 large quantity appears to us to represent a degenerative reaction ; 

 it was accompanied by a most striking increase of leucocytes,, 

 which tended to distend the vessels and to collect in clumps, 

 phenomena which are abnormal in our experience in the oyster. 

 The presence of the copper in the leucocytes in these cases might 

 be compared to that of the iron which is met with in some of the 

 leucocytes in cases of old haemorrhages, pernicious anaemia, or in 

 other cases where iron is set free. We are not prepared to state 

 whether copper in the food can bring about the condition, but cer- 

 tainly we have abundant evidence to show that it can occur where 

 no copper mines or other evident sources of copper are present. 



We are inclined to suggest that the increase of copper may be due 

 to a disturbed metabolism, whereby the normal copper of the 

 haemocyanin, which is probably passing through the body in 

 minute amounts, ceases to be removed, and so becomes stored up in 

 certain cells. 



Our results also show that haematoxylin is a most valuable 

 reagent, not only as Macallum has shown in the case of iron, but also 

 in that of copper, and that care must be taken to distinguish between 

 the two reactions ; and this must be especially the case in those 

 invertebrata where copper plays an important role in the physiology 

 of the blood. 



" Stress and other Effects produced in Eesin and in a Viscid 

 Compound of Eesin and Oil by Electrification." By J. W_ 

 Swan, F.R.S. Received May 17,— Read June 17, 1897. 



(Plates 1—4.) 



While making an experiment with the object of finding the degree 

 of resistance to puncture offered by paper coated with a soft com- 

 pound of resin and oil, when placed between the secondary terminals 

 of an induction coil, the tension being regulated by a spark-gap in a 

 parallel branch of the circuit, observed that on the passage of a 

 spark at the spark-gap, while no spark passed between the paper- 

 separated terminals, a sudden roughening or puckering of the 

 previously smooth surface of the coating took place. 



A number of experiments were made with the object of ascertain- 

 ing the nature of the action which produced this effect, and these led 

 to further experiments and to results which, though closely related 

 to well-known phenomena, possess features of novelty and interest. 



