EXPERIMENTS WITH RADIUM 107 



the stages which these bodies also do ; but we have 

 no knowledge of any bodies which can perform the 

 cyclic process so completely. It has been suggested 

 that the products of radium and bouillon are like the 

 microscopic crystals described by those already men- 

 tioned, and also by Schenck in his admirable little 

 work which has just recently been published.^ We 

 have never thought of classifying or identifying the 

 bodies therein described with the " plastide particles " 

 in bouillon, some of which have been so many times 

 observed. The two indeed are totally distinct, the 

 smaller ones behaving like bubbles or more accu- 

 rately like oily drops, possessing no indication 

 whatsoever of an internal structure other than 

 that which we may associate with crystalline 

 forms ; whilst the larger ones are much too large, 

 and show no signs of disintegration, but give the 

 beautiful characteristic figures as in crystals under 

 the polariscope. Even the comparatively small ones 

 exhibit, to some extent at least, some slight polari- 

 scope effects. But they are obviously, to anybody 

 who has seen them, quite different from those 

 which are brought about in the culture medium 

 under the influence of radium. They do not 

 stain — at least they have not been found to do 

 so — as the radium bodies do, and they do not 

 manifest the properties which have so attracted 

 our attention with the latter ; the two, so far 

 as can be judged, are totally distinct, as distinct 

 as coal is from potatoes. 



It will be urged — in fact it has been urged — that 

 1 Kristallinische Flussigkeiten und Pliissige Kristalle. 



