56 PKOCEEDINGS OF SOCIETIES. 



Professor Eupert Jones then read a highly interesting paper " On 

 the Foraminifera, with special reference to their Variability of Form." 

 The subject was illustrated by a large number of diagrams and en- 

 larged models in plaster, &c., as well as by an extensive collection of 

 mounted specimens. (The paper will appear in the next number, not 

 having been received by the Editor.) 



The President expressed the pleasure with which he had listened 

 to Professor Jones, and thought there were in the paper a great many 

 points which claimed their attention, the principal being of course 

 the remarkable variability of these little organisms. He hoped this 

 would be experimentally tested by keeping the creatures in confine- 

 ment and breeding them. It really seemed almost impossible to draw 

 a line in any particular part of the series between the species, and one 

 felt it very difiBcult under such circumstances to say what a species 

 was. Occurring as they did in such immense numbers, they supplied 

 the opportunity of studying the many differences of form and varia- 

 tions from a type that were likely to occur. He presumed that no 

 experiments had been tried on the subject, but it aj)peared to him 

 very interesting to keep these little creatures for the purpose of such 

 a study if it could be done. The question of opacity of certain forms 

 must be due in some degree to the ultimate molecular sti'ucture of 

 the shells, some allowing the light to pass through more freely than 

 others. 



Mr. C. Stewart said that amongst so large a class of bodies there 

 must be a great number of intermediate forms, and not only would 

 the forms themselves vary, but the intermediate links would constantly 

 vary also. With regard to the structure and transparency of these 

 shells, it would be found that they polarized light in a very marked 

 and definite manner. All the hyaline ones showed the " black cross " 

 in the clearest way, but all the porcellanous varieties showed only 

 a general irregular mottling, and they did not lose that aj^pearance 

 by alteration of the plane of polarization, but in any position still 

 appeared generally mottled. 



The President thought the remarks of Mr. Stewart very im- 

 portant, the cause of the difference observed between the two kinds 

 in polarized light was no doubt due to their structure. If the car- 

 bonate of lime were arranged in crystals all perpendicular to the 

 surface of curvature, that would account for the " black cross." The 

 other appearance was analogous to what would occur if the particles 

 were arranged in every possible direction, the one being a regular 

 and the other a promiscuous arrangement. 



A cordial vote of thanks to Professor Jones was unanimously 

 carried. 



The Scieniific Evening, November 24, 1875. 



The attendance on this occasion was very good, and from the 

 subjoined list it will be seen that many objects of interest were 

 exhibited. 



The President's apparatus for measui'ing the exact position of 

 absorption bands, and which is described and figured in the December 



