393 



which go on in the cells of the inflamed tissue purely passive, 

 mere phenomena of retrograde metamorphosis ? 



I find the evidence insufficient as yet to afford satisfactory 

 answers to such questions. The observations made by 

 Cohnheim on the connective tissue corpuscles of the tongue 

 of the frog are not conclusive in themselves, and Strieker's 

 studies on the same subject^ show the necessity of further 

 labour in this direction before the possible multiplication of 

 these elements in inflammation can be denied. As to the 

 doctrine that the white corpuscles, after their escape from 

 the blood-vessels, are transformed into the elements of normal 

 or pathological tissues, the facts hitherto brought forward 

 can scarcely be said to do more than raise it to the rank of 

 an ingenious hypothesis. The actual steps of this transfor- 

 mation, if it does occur, have yet to be observed. 



In conclusion, I may remark that, as the preparations 

 referred to in this paper form a portion of the Microscopical 

 Collection of the Museum, they can be examined by any 

 professional microscopist who may visit that institution. 



The photographs* which accompany this paper were pre- 

 pared by myself in accordance with the methods described 

 on former occasions. 



On an Aplanatic Searcher, audits Effects in Improving 

 High-Power Definition in the Microscope. By 

 G.W. IloYSTON-PiGOTT,M.A.,M.D. Cantab., M.R.C.P., 

 F.R.A.S., F.C.P.S., formerly Fellow of St. Peter's Col- 

 lege, Cambridge.^ 



The Aplanatic Searcher is intended to improve the pene- 

 tration, amplify magnifying power, intensify definition, and 

 raise the objective someAvhat further from its dangerous 

 proximity to the delicate covering-glass indispensable to the 

 observation of objects under very high powers. 



The inquiry into the practicability of improving the per- 

 formance of microscopic object-glasses of the very finest 

 known quality was suggested by an accidental resolution in 

 1862 of the Podura markings into black beads. This led to 



' ' Studien aus dem Institute fiir Experimentelle Pathologic in Wieu 

 aus dem Jahre, 1869.' Wien, 1870. 



2 Dr. Rojstou-Pigott has communicated to us a valuable paper and 

 drawings describing this instrument and its performances, which the pressure 

 of matter compels us to postpone until January, — Ed. Q,, J. M. S. 



