QUARTERLY CHRONICLE. 277 



special toxic effect of the poison of the snake is due to its 

 destructive effects on the red blood-corpuscle. 



Mr. Frank Buckland also, in a recent note on this subject, 

 arrives at a similar conclusion. He says that the poison 

 seems to " curdle" the blood. 



" The Mic7'oscopical Illumination of Diatoms." — A paper 

 read before the Societe Philomathique, of Paris, on April 

 18th, on the above subject, contains one or two points of in- 

 terest. The author, M. Freminau, makes the following 

 remarks: — "The ordinary method of examining the Dia- 

 tomacese consists in illuminating the object by means of 

 oblique light, so arranged that the reflected bundle strikes it 

 at an angle of 45°. This method he considers most unsatis- 

 factory. Here, then, are three other ways of illuminating, 

 say Navicula. The first consists in passing solar light 

 directly through the object, and protecting the retina by a 

 blackened glass placed over the objective. This mode, he 

 says, gives the strife very well. The second consists in em- 

 ploying the solar spectrum, reflecting from the mirror the 

 light between orange-yellow and greenish-yellow. The third 

 consists, whatever may be the magnification, in illuminating 

 the Navicnla directly, as opaque objects are illuminated, but 

 by a somewhat different process. We place, says the author, 

 an equilateral prism on the level of the stage, and then we 

 direct a bundle of rays — either white or spectral — between 

 the preparation and the object, and we see the striae black 

 upon a coloured ground. These processes do not require 

 great experience for their satisfactory employment, but may 

 readily be adopted by the amateur. These methods, says the 

 author, have given me valuable assistance in the examination 

 of Diatomacese, and they are equally applicable to other sub- 

 stances. He suggests the following substitute for solar 

 light : — A hemispherical condenser is placed in front of a 

 conical reflector, and a lamp is set between the two. This 

 lamp should be a magnesium lamp, or a lamp in the centre 

 of whose flame a cylinder of solid magnesia has been placed. 



British Association. — 1. '' On, the Homologies and Notation 

 of the Teeth of Mammalia," by W. H. Flower, F.R.S. The 

 author stated that he proposed to bring before the meeting 

 an endeavour to ascertain how much of the generally adopted 

 system of classification of the homologies and notation of 

 the teeth of the mammalia, a system mainly owing to tlie 

 researches of Professor Owen (whose labours in this depart- 

 ment of anatomy he gratefully acknowledged), stands the 

 test of renewed investigations, how much seems doubtful and 

 requires further examination before it can be received into 



