May 25, 1905] 



NA TURE 



79 



too small for a bacterial growth. It was not at all obvious 

 how bacteria could have remained in one set of tubes and 

 not in the other, unless the radium salt itself acted as a 

 shield, so to speak, for any spores which may originally 

 have become mixed with the salt, perhaps during its manu- 

 facture, and when embedded in it could resist even the 

 severe process of sterilisation to which it was submitted. 



On heating the culture and re-sterilising the medium, the 

 bacterial-like forms completely disappeared ; but only 

 temporarily, for after some days they were again visible 

 when examined in a microscopic slide. Nay, more, 

 they disappeared in the slides when these were ex- 

 posed to diffused daylight for some hours, but re- 

 appeared again after a few days when kept in the dark. 

 Thus it seems quite conclusive that whatever they may 

 be,_ their presence is at any rate due to the spontaneous 

 action of the radium salt upon the culture medium, and 

 not alone to the influence of anything which previously 

 existed therein. 



When washed they are found to be soluble in warm 

 water, and however much they may resemble microbes. 



they cannot for this reason be identified with them, as 

 also for the fact that they do not give subcultures as 

 bacteria should. ; 



Prof. Sims Woodhead has very kindly opened some of 

 the test-tubes and examined them from the bacteriological 

 point of view. His observations fully confirm my own. 

 He assures me that they are not bacteria, and suggests 

 that they might possibly be crystals. They are, at any 

 rate, not contaminations. 



I have tried to identify them with many crystalline 

 bodies, and the nearest approximation to this form appears 

 to be that of the crystals of calcium carbonate, but these 

 are many times larger, and, in fact, of a different order of 

 magnitude altogether, being visible under comparatively 

 low powers ; and are, moreover, insoluble in water. 



\ careful and prolonged examination of their structure, 

 behaviour, and development leaves little doubt in my mind 

 that they are highly organised bodies, although not 

 bacteria. 



Unfortunately the quantity is so very minute that a 

 chemical analysis of their composition is extremely difficult. 

 The amount of salt in the first instance is so small, and 

 the number of aggregates, or whatever they may be, thus 

 produced perhaps still smaller. 



The most effective method of studying their properties, 



NO. 1856, VOL. 72] 



from the physicist's point of view, is that of long and, so 

 far as possible, continual observation, a method similar 

 to that which the astronomer is bound to adopt in his 

 study of bodies over which he has not the control to deal 

 with as he pleases. 



From the accompanying photographs it will be observed 

 that they are not all of the same size ; they range from 

 about 03 \j. to the minutest specks ; they are mostly, if 

 not altogether, all of the same shape, and show distinct 

 signs of growth ; the larger ones appear to have sprung 

 from smaller forms, and these in turn from still smaller 

 ones, and they have all probably arisen in some way from 

 the invisible particles of radium.- 



Fig. 2 distinctly shows the existence of nuclei in the 

 larger and more highly developed forms, whilst Fig. 3 

 reveals, though indistinctly, what is their most remarkable 

 property of all, and that is their subdivision when a certain 

 size is reached. They do not grow beyond this size, but 

 subdivide. 



These photographs, together with the numerous results 

 of eye observations, which indicate that a continuous 

 growth and development take place, followed by segrega- 

 tion, leave little doubt that whilst on the one hand thev 

 cannot be said to be bacteria, they cannot be regarded as 

 crystals either in the sense of being merely aggregates 

 of symmetrically arranged groups of molecules, which 

 crystals are supposed to be. The stoppage of growth at 

 a particular stage of development is a clear indication of 

 a continuous adjustment of internal to external relations, 

 and thus suggests vitality. 



They are clearly something more than mere aggregates 

 in so far as they are not merely capable of growth, but 

 also of subdivision, possibly of reproduction, and certainlv 

 of decay. 



The subcultures do show, however slightly, some indica- 

 cation of growth after four or five weeks, although that 

 growth is, I understand, too small for a bacterial sub- 

 culture. Moreover, when examined in the polariscope thev 

 have not been found to yield the characteristic figures and 

 changes of colour which crystals generally give. 



Thus for these reasons I have been led to regard them 

 as colloidal rather than as crystalline bodies, and prob- 

 ably more of the nature of " dynamical aggregates " than 

 of " static aggregates," of which crystals are composed. 



There appears to be a tendency amongst text-book 

 writers to classify minute bodies which are not bacteria 

 as crystals, but really without sufficient reason, and as 

 these bodies cannot be identified with microbes, on the 

 one hand, nor with crystals on the other, I have ventured, 

 for convenience, in order to distinguish them from either 

 of these, to give them a new name, Radiobes, which might, 

 on the whole, be more appropriate as indicating their 

 resemblance to microbes, as well as their distinct nature 

 and origin. 



Some slightly radio-active bodies appear also to produce 

 these effects after many weeks. 



A more detailed account of these e.xperiments will be 

 published shortly. This note merely contains some of the 

 principal points so far observed. 



I have to thank Mr. W. Mitchell, who sterilised the 

 tubes, for the assistance he has rendered in these experi- 

 ments. John Butler Burke. 



Cavendish Laboratory, Cambridge, May 10. 



The Consolidation of the Earth. 



There are several points in Dr. See's last letter (Nature, 

 May 11) calling for remark from the geological point of 

 view. 



(i) The effect of (hydrostatic) pressure at depths tends 

 not to liquefaction (as in the case of the ice of a glacier) 

 but to promote crystallisation, the condition of the greatest 

 density of mineral matter, as I showed years ago in my 

 little work on metamorphism in discussing the relation of 

 the crystalline to the vitreous states. It is here that the 

 importance of " solid-liquid critical state " comes in. 



(2) We have no right to assume the existence at any 

 stage of the history of our planet of a mere molten bail 

 radiating heat directly into cold space, since in that 

 ■' pre-oceanic stage " it was surrounded by a non-conduct- 



