152 NATURAL SCIENCE. March, 



wherever formed, is or has been due to one set of causes, but it is 

 not too much to ask that granules shown in any one micro-slide shall 

 have originated by one method. There should be no selection of 

 isolated granules from a large number of slides, when the majority of 

 other granules, equally clear, do not give that evidence which 

 coincides with one's views. We are far from saying that oolitic 

 granules are never of organic origin. Rothpletz has shown that 

 structures somewhat similar to those found in oolite limestone are 

 produced by fission algae, and it may be observed that a like 

 structure is seen in many calculi. At the same time, it cannot be 

 ignored that perfect oolitic granules have been made artificially by 

 purely chemical means, and "oolitic granules" are not unknown to be 

 forming under conditions totally unlike those described by Rothpletz 

 and others. If Mr. Wethered had contented himself with drawing 

 attention to the similarity of some of the granules exhibited by him 

 to those of the Great Salt Lake mentioned by Rothpletz and 

 described by certain American authors, we should have nothing to 

 say ; but when he asks us to recognise systems of tubules running 

 concentrically round the nuclei of granules, and others radiating from 

 these nuclei, we think he is demanding too much — especially with 

 reference to the " radiating tubules." We are not of those who 

 believe that, in order to show the organic origin of the granules, it is 

 necessary to prove the existence of tubules, though, of course, when 

 these can be satisfactorily demonstrated, they add interest to the 

 problem. We are pleased to see, however, that this difficult subject 

 is receiving the attention it deserves, and have no doubt that the 

 researches of Mr. Wethered and others will do much towards its 

 ultimate satisfactory elucidation. 



Peridotites and Phosphates. 



That close and painstaking observer, Mr. T. H. Holland, who 

 so recently distinguished himself by his work on the Gohna landslip, 

 has returned to the less exciting details of Indian igneous rocks. 

 In two papers in the Records of the Geological Suvvey of India (vol. xxvii., 

 pp. 129-146) he describes certain peridotites from Bengal. It is 

 quite refreshing to be provided with a summary of the literature 

 poured out upon this timid and retiring group of rocks at a time 

 when they were a. prevailing fashion — say, in 1885. We fancy that a 

 somewhat pale biotite is commoner in peridotites than Mr. Holland 

 supposes ; but his phosphatic series from the Lower Gondwana rocks 

 is a distinct addition to our knowledge. In some of these apatite is 

 so abundant, in characteristic rod-shaped crystals, as to have been 

 mistaken by a previous observer for felspar, and as to form a near 

 approach to ophitic structure in the larger crystals of biotite. These 

 rocks are intrusive in coals in a manner that suggests the possibility 

 of the occurrence of diamond as a contact-product, since, as Mr. 



