318 The Microscope. 



diameters will answer most all purposes with the above drugs and 

 preparations, but a higher power must be employed for the follow- 

 ing : Aloe, amylum, gossyprum, kamala, lupulinum and lycopodium. 

 "Every druggist should provide himself or herself with a 

 microscope, or magnifying glass, as they are commonly called. One 

 that magnifies ten diameters can be purchased at prices varying 

 from twenty-five cents to two dollars and fifty cents, according to 

 the quality and style. An ordinary ' pocket magnifying glass ' is 

 very serviceable." 



Anatomy and Physiology of Stinging Hairs. — Dr. G. Haber- 

 landt has examined the structure of the stinging hairs in a number 

 of plants. The main features show a great uniformity in the 

 multicellular base, surmounted by the very large secreting cell. 

 Below the silicified apex of the latter, the cell-wall is always very 

 thin. In Loasa paparerifolia the brittleness is occasioned by the 

 deposition, not of silica, but of calcium carbonate, and in Jatropha 

 stimulans, by liquefication. In other cases the liquefied apex is 

 partially or entirely wanting. The substance which gives the 

 stinging properties to the fluid of the glands of the common 

 stinging nettle, is not, as has been generally supposed, formic acid, 

 which could not produce the effect in such small quantities. Dr. 

 Haberlandt also states that the irritation must be produced by a 

 fixed substance, since the dried contents of the gland will cause the 

 ordinary effect of a nettle sting if introduced beneath the skin. He 

 finds always in the fluid a substance which exhibits all the properties 

 of an albumenoid. The substance which produces the inflammation 

 is probably a compound of the nature of an unformed ferment. — 

 B. M. S. Journal. 



Nucleus in Frog's Ovum. — Dr. G. Thin describes conditions of 

 the nucleus in the ova of Rana temporaria between the stages of 

 division into four segments and that of the appearance of the 

 morula condition. Sections were made from egg hardened in bichro- 

 mate of potash and stained with picro-carmine. These methods 

 were not such as to enable the nuclear network to be satisfactorily 

 made out. In the first stage observed, or that of a "tablet-nucleus," 

 an unformed substance was found infiltrating the yolk in certain 

 parts of the segments. Then came the diffuse granular nucleus, in 

 which minute yolk tablets were found in the carmine-stained nuclear 

 area. In the homogeneous nucleus the nuclear substance stains 

 homogeneously in carmine, has distinct boundaries, and no yolk 

 tablets or pigments. The fourth stage is that of the shrunk nucleus, 



