ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 547 



species, of which forty were adult forms. Saville Kent's method of 

 preparing and mounting his specimens was described in Science Gossip, 

 1882. The specimens, adult, larvae, or ova, were killed by momentary 

 immersion in boiling water. They were mounted in a cell of suitable 

 depth in either camphor-water, or a solution of 1 of spirit to 4 or 5 of . 

 water. Specimens fourteen years old so preserved retained their pristine 

 form and brilliance of colour. The Hon. Sec. read a paper communi- 

 cated by Mr. E. M. Nelson, F.R.M S., on " Methods of Illumination." 

 The paper dealt first with mirror illumination, and the right and wrong 

 ways of getting centred illumination with concave mirrors only. The 

 use of ground glass was referred to, and, generally, its use deprecated. 

 The least harmful position for it is below the substage condenser. The 

 very cheapest form of substage condenser will give a better image than 

 is obtainable with ground glass. In dealing with the use of screens for 

 visual work, it was stated that the normal eye is most sensitive to fine 

 detail when the light is peacock-green in colour. 



The 475th Ordinary Meeting of the Society was held on June 27. 

 Mr. C. F. Rousselet, F.R.M.S., Vice-President, in the Chair. A paper 

 by Dr. E. Penard, on " Some Rhizopods from Sierra Leone," was read 

 by Mr. A. Earland, F.R.M. S. The material examined was supplied by 

 Mr. G. H.Wailes, and yielded fourteen species of fresh-water Rhizopods, 

 of which three were new, and four at least might be considered as 

 special forms and varieties. The genera represented were Centrop>/.ri$ 

 (2 species), Difflugia (5 species, 2 new), Euglgpha (2 species), Lesqaer- 

 entia (3 species, 1 new), and Pontigulatia (2 species). The new species 

 will be fully described and figured in the next issue of the Club's 

 Journal. Mr. T. A. O'Donohoe read a note on " Dimorphism in the 

 Spermatozoa of the Flea and the Blow-fly." In the common flea two 

 forms were found, both of which are very large compared with those of 

 man, whose spermatozoa have an average length of 0*06 mm. In the 

 flea the larger form is 0- 7 to 0*45 mm. long, and the smaller form about 

 half these lengths. Carbol-fuchsin or gentian-violet are suitable stains. 

 The spermatozoa of the blow-fly are much smaller than those of the flea. 

 The two forms observed do not differ much in length, but one is very 

 much thicker than the other. (For other cases of dimorphic spermatozoa 

 see this Journal, 1905, p. 34.) A paper on " Normal and Abnormal 

 Vision in Microscope Work," by E. M. Nelson, F.R.M.S., was read by the 

 Assist. Hon. Sec. The experiments described showed that differences 

 from normal sight produced the greatest effect with low powers, such as 

 those obtained with a " loup." 



B. Technique.* 

 (1) Collecting- Objects, including Culture Processes. 



Examination of Water for Typhoid Bacilli by the Complement- 

 fixation Method.f — G. Volpino and E. Cler employ the complement- 



* This division contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Embedding and Microtomes ; 

 (4) Staining and Injecting ; (5) Mounting, including Slides, preservative fluids, etc. ; 

 (6) Miscellaneous. 



t Centrabl. Bakt., lte Abt., lviii. (1911) pp. 392-9. 



