110 SUMMARY OF CURRENT EESEAECHES RELATING TO 



(5) Mounting-, including- Slides, Preservative Fluids, &c. 



Making Preparations of Crystals for the Micropolariscope.*— 

 S. E. Dowdy says that the first essential of success is to get the slides 

 perfectly free from grease. Rubbing them with a paste made by 

 working up a little prepared chalk with equal parts of rectified spirit 

 and liquid ammonia, drying, and finally polishing on chamois leather, 

 answers well. Make a saturated solution of the chemical in cold distilled 

 water in a test-tube. Warm the supernatant fluid so that it may take 

 up a little more of the salt in solution. Deposit a drop or two of the 

 warm solution in the centre of a slide and allow it to spread. If it do 

 not form a film but remain as a globule it is a sign that the slide is still 

 greasy. If a film forms, it should be covered with a watch-glass and the 

 slide put aside to cool. The results are better from slow cooling, but the 

 process may be hastened by heating the liquid on the slide until a thin 

 film of salt appears at the edge and then putting aside to cool. When 

 formed, the crystals should be mounted at once in xylol-balsam of thick 

 viscid consistence. 



(6) Miscellaneous. 



Interesting" Extract from Hooke.f — ■" Nature is not to be limited by 

 our narrow apprehensions ; future improvements of glasses may yet 

 further enlighten our understanding and ocular inspection may demon- 

 strate that which as yet we may think too extravagant either to suppose 

 or feign." 



This quotation occurs in connection with a letter received from " the 

 ingenious and inquisitive Mr. Leeuwenhoeck, of Delft," sent October 5, 



1677. In this letter, Leeuwenhoeck speaks of the vast number of 

 animalcules to be seen in an infusion of pepper, and Hooke calculates 

 that over 8,000,000 of these minute animals exist in a single drop. 



The work from which the extract is taken is entitled ' Lectures and 

 Collections made by Robert Hooke, Secretary of the Royal Society,' 



1678, p. 118. The latter part of this collection has a second title, 

 ' Microscopium or some new Discoveries made with and concerning 

 Microscopes.' 



Handbook of Instructions for Collectors.! — The authorities of the 

 British Museum (Natural History) have issued in book form the series 

 of pamphlets, treating of the collecting and preservation of specimens, 

 which were chiefly drawn up for the better information of voluntary 

 collectors resident abroad. The various chapters have been written by 

 different members of the staff of the Natural History Museum. Much 

 valuable information is contained in the booklet, though a few more 

 diagrams would have been useful adjuncts to the verbal descriptions. 

 On the other hand, illustrations such as that of a cyanide bottle seem 

 somewhat superfluous, and the morality of the advice (p. 129) to bribe 

 customs officers is more than doubtful. 



Physiological Histology.§ — G. Mann's Methods and Theory of 

 Physiological Histology is bound to command widespread interest among 



* Engl. Mech., lxxvi. (1902) pp. 319-20. t Brit, Mus. Cat., 233 h. 5. 



X Printed by order of the Trustees of the British Museum, London, 1902, 137 pp., 

 with illustrations. § Oxford, Clarendon Press, 1902, vii. and 488 pp. 



