THE society's XOTE-BOOKS. 129 



the book to advantage, and learn how to interpret their observa- 

 tions, for assuredly in many cases " things are not as they seem." 

 The Quekett JournaL No. 38 (Oct., 1878), contains an excellent 

 article on " 'The Influence of Diffraction in Microscopic Vision," 

 by Air. Frank Crisp, F.R.M.S., which may be studied with ad- 

 vantage. 



Many slides show most varied and curious diffraction spectra, 

 when closely looked through at a distant light ; notably, Feathers, 

 Hairs, Fabrics, Fish Scales, certain Membranous Wings, Leaves 

 of Endogenous Plants, Longitudinal sections of various Woods, 

 etc. etc. Fine rulings on glass (2000 and upwards to the inch), 

 especially radial bands and cross angular ruling, give brilliant and 

 well-defined spectra ; but the most remarkable spectrum I ever 

 saw was obtained by looking through the Palate of a Limax^ 

 mounted many years ago in balsam. W. Teasdale. 



EXPLANATION OF PLATE XIII. 



Fig. \.-' Bnh^arm hiqninaus. a.a. , asci, with their contained spores, 

 sp., in the mature condition ; h.b., immature asci, segmenta- 

 tion in various stages of development; p.p., paraphyses ; 

 str., stroma, a gelatino-corneous material, with delicate inter- 

 lacing filaments interspersed throughout its substance, x 400. 



,, 2. — Diagrammatic sketch by Dr. Parsons, showing, r., receptacle; 

 h., hymenium. 



,, 3. — Shows the remarkable interlacement of the fibres of Keratose 

 Sponge, solid in the young state, but becoming tubular with 

 advancing age, and cohesion of the fibres in many places 

 where they come in contact, x 50. 



,, 4. — Filarla bronchialis, the entire worm, as seen with a low power, 

 X 12. 



,, 5. — The head, with m,outh, and very muscular oesophagus, x 50. 



,, 0. — Part of body of the worm, showing piece of intestine, ovary, 

 and nearly ripe ova, x 50. 



,, 7. — Transverse section of Medical Leech, x 5. 



,, 8. — Longitudinal section of same, shown also with low power. 



,, i>. — Portion of the intermediate layer of muscles, unstriped, 

 X 50. 



,, 10.— Tart of the longitudinal vessels, with delicate spiral muscuhtr 

 fibre coiled round it. There are but two coats, the inner an 

 exceedingly thin membrane. 



,, 11. — Portitm of glandular structure ap])ended to the intestine, 

 X 50. 



All drawn by Tufien West except Fig. 2, 



