THE society's NOTE BOOKS. 125 



many millions must be produced by a single individual. The asci 

 are erect and attached by their narrow end to the surface of the 

 stroma, but owing to the toughness of the latter and the briltleness 

 and opacity of the hymenium, great skill is required to make a 

 section of the whole plant sufficiently thin to show the parts /;/ situ. 



H. F. Parsons. 



Santonine Crystals, prepared by dissolving Santonine in 

 Chloroform, then dropping the solution on a hot slide and subse- 

 quently mounted in Castor Oil. C. F. Tootal. 



Section of Potato, showing one or two interesting points, 

 notably some minute sieve tubes, lying in rows of several near the 

 vascular system, of which indeed they form a part. They will 

 require a rather high power and careful illumination. The 

 slide also shows crystals of aluerone. 



H. POCKLINGTON. 



Aluerone. — Is aluerone soluble in water ? The crystals had 

 evidently disappeared in or immediately after mounting. Can 

 any one give an exact account of this substance ? 



J. Abbott. 



Polarising Objects. ^All structures capable of showing varied 

 colours under the influence of polarised light are not necessarily 

 legitimate " Polariscope objects," though popularly classed, sold, 

 and bought as such. W. Teasdale. 



Cellularia avis.— This polypidom of a zoophyte unfortunately 

 depolarises light, and so may be exhibited as a chromatically 

 confused pretty object, instead of being intelligently considered 

 under suitable illumination. It is a caution to mount such objects 

 opaque that they may not be trifled with. 



W. Teasdale. 



Sponge Fibre. — The, dark field of the polariscope (without 

 selenite) offers some little advantage over other means of viewing 

 this object as it is mounted ; "red selenite " is an aggravation to be 

 avoided. Chance snips at the chitinous endo-skeletons of sponges 

 whether picked up on the beach or in the bath-room, may furnish 

 " gorgeous " micro-objects, but not highly instructive ones. 



W. Teasdale. 



Crystal Slides. — I avail myself of this opportunity of putting 

 in a note on the various means by which forms of crystallisation 

 may be modified, and how some particular abnormal forms of 

 crystals may be obtained. 



ist. — By using various solvents. 



2nd. — By varying strength of solution. 



