THYMOL AS A POLARISCOPIC OBJECT. 



31 



In addition to the three kinds of tissue already referred to as 

 constituting the thallus, an infra-cortical layer of exactly the same 

 structure as the supra-cortical layer, may be distinguished in 

 immediate contiguity with that part of the hyphal tissue which is 

 below the apothecium. After reaching points perpendicular to 

 the ends of the apothecium, this infra-cortical layer gradually 

 passes into the hyphal tissue. 



To elucidate the study of the asci and paraphyses, the section 

 may be immersed for about half-a-minute in a 50% solution of 

 hydrate of potash, which causes the parts to swell and sepa- 

 rate. An aqueous solution of iodine is also useful for tinging 

 the hymenium blue, and for testing the maturity of the spores, 

 which will remain uncoloured if only in an embryonic state. 



The specimen from which our illustration is taken was ob- 

 tained by imbedding the lichen in paraffine wax, and slicing with 

 a sharp razor. The section should be floated (not lifted) from the 

 blade, and kept in lukewarm water, until all air is eliminated from 

 the tissues, when it may be mounted in glycerine jelly. 



EXPLANATION OF PLATE Y. 



a. a. — The Cortical layer. 

 6. 6. — The Stratum-gonicliale. 

 c. c. — The Medullary layer. 



Drawn by Arthur J. Doherty. 



l^jj I L I B R A R Y 



^b^mol aa a polariecopic ©bjcct 



By Dr. T. S. Ralph, Victoria. 



THYMOL, said to be a product of the Labitor, is a most 

 splendid polariscopic object. In the first place, I beg to 

 say that Thymol is really a purified product of an umbili- 

 fer of India, and goes into the market as ajoivaji. If a very small 

 piece of Thymol, about the size of a mustard-seed (or perhaps two). 



