44 



NOTES AND MEMORANDA. 



and in by far the majority of cases this is not, as might be expected, 

 coloured red, but hfematoxylin. Dr. Mayer expects to be able to give the 

 explanation hereafter of this strange phenomenon, which, however, is no 

 detriment to the process. In consequence of the precision and tint of 

 the stain, the preparations are for the most part not to be distinguished 

 from those obtained with hsematoxylin. The cochineal tincture also 

 possesses, in common with the well-known alcoholic hsematoxylin 

 solution of Kleinenberg, the property of m.t altering the tissues ; on 

 the other hand, it compares favourably with it in the simplicity of its 

 production and apj^licatiun, as also in the hold taken by the stain, 

 which in this respect is equal to carmine. On the other hand, there 

 is the defect that hitherto the attempt to stain large objects sufficiently 

 deeply has not always succeeded ; although the spinal marrow of 

 the calf, in pieces one centimetre long and more, could be stained uni- 

 formly and deeply enough. 



With a little care, permanent overstaining need not be feared, and 

 can be removed by washing in acid alcohol (a drop of muriatic acid 

 to about 10 c. cm. of 70 per cent, alcohol). 



Prazmowski's Heliostat. — The woodcut represents this instru- 

 ment, which, it is claimed, is much less complicated and cheaper than 

 any existing form, and more easily regulated. The drum contains, as 

 usual, the clock movement, and rotates a mirror upon its axis once in 

 forty-eight hours. On the circumference of the drum is a dial with 



AfA^f/C.-,A 



the hours marked upon it, the spaces between each hour being divided 

 into intervals of ten minutes. The drum rests upon supports, which 

 allow it to be inclined in such a manner as to make the axis of the 

 movement coincide with the direction of the earth's axis at the place 

 where it is used. 



This direction, which is given by the latitude of the place, need 

 not necessarily be known to the operator, the adjustment of the instru- 

 ment with respect to the latitude and the declination of the sun cor- 

 responding to the day of the year, being effected at once, and, so to 

 speak, automatically. The aj^paratus is fixed after adjustment in 



