216 



THE AMERICAN MONTHLY 



[November, 



and then scratch the gelatin surface as 

 Prof. Pillsbury suggests. Any person who 

 has patience and can draw a hne could 

 thus prepare many slides for his lantern at 

 comparatively low cost. 



— Dr. H. DeVries has been making a 

 studyof the vacuoles of vegetable cells, and 

 the results which he has achieved are of 

 considerable interest. He has proved that 

 a vacuole is not merely a sap cavity hol- 

 lowed out in the protoplasm, but that it 

 has a distinct inclosing membrane different 

 from the rest of the protoplasm. For this 

 membrane he proposes the name tono- 

 plast. His mode of distinguishing it was 

 by the use of a \o% solution of potassium 

 nitrate, which almost immediately kills 

 the rest of the protoplasm but does not 

 kill the inclosing membrane of the vacu- 

 ole until the lapse of some time. The 

 dead protoplasm may then readily be 

 stained by means of eosin or other suit- 

 able dyes, while the living tonoplast re- 

 mains unstained and may therefore be 

 readily distinguished. He further finds 

 that the tonoplast agrees in essential struc- 

 ture with what has been termed the pri- 

 mordial utricle of the cell or the inner cell 

 membrane. Like it the protoplasm com- 

 posing it is firmer and less permeable than 

 the rest, and they resemble each other also 

 in the fact that they e.\crete certain defi- 

 nite substance, as cellulose, vegetable, 

 acids, etc. Dr. DeVries also ascribes the 

 phenomenon which Darwin called 'aggre- 

 gation of the protoplasm ' to be contraction 

 and division of the vacuoles. — From West- 

 ern Druggist, Oct., '86, p. 391. 



— Prof. C. S. Minot, in Zeitsche f. 

 Wiss Mikroskopie, iii, p. 173, states with 

 regard to absolute alcohol : ' My experi- 

 ence has led me to question whether ab- 

 solute alcohol which retails in America at 

 one dollar a quart is, I will say, not a 

 necessity, but even an advantage for the 

 preservation or hardening of histological 

 material, or at least of vertibrate tissues. 

 One frequently encounters the direction 

 to employ absolute alcohol in conjunction 

 with this or that method. After repeated 

 tests I have found 96% entirely sufficient 

 for all the manipulations for which the 

 absolute had been recommended. At 

 present I know of no application of abso- 

 lute alcohol in histology which I can re- 

 gard as anything but an unnecessary 

 extravagance.' Prof. Minot further ob- 

 jects to the permanent preservation of 

 material in alcohol stronger than 80%. 

 It is the custom of some of the best histol- 

 ogists to permanently keep their material 



in jo% alcohol in vials, and to keep these 

 in jars of alcohol of about the same 

 strength, thus preventing change so far 

 as possible in the small vials. The use 

 of strong alcohol for permanent preserva- 

 tion is of no advantage whatever, as 70% 

 is strong enough, and the stronger alco- 

 hols shrink and distort the specimen 

 Before imbedding, the specimen must 

 stand a day or so in strong alcohol. 



— In the same article from the Zeits. f. 

 W. Mikros., Prof. Minot says that ' Ben- 

 zole can replace the much dearer xylol 

 for cleaning sections, cleansing lenses, 

 diluting Canada balsam, etc. Pure ben- 

 zole has the property of evaporating with- 

 out leaving a residue.' 



— Picric acid car/nine. From the same 

 article we extract the following : There is 

 a good way to secure a permanent picro- 

 carmine solution without the use of am- 

 monia. ' Boil one gramme of the best 

 powdered carmine with 200 c.c. of water 

 plus an excess of picric acid for half an 

 hour. Allow it to stand and cool, decant 

 the clear fluid, add fresh water, and, if 

 necessary, picric acid ; boil, cool, and 

 decant ; repeat this operation until all the 

 carmine is dissolved. Place the decanted 

 fluid in an evaporating dish, add about 19 

 thymol, and stand in a warm place until 

 the volume is reduced to 25 c.c. ; let the 

 solution cool ; filter ; wash out the residue, 

 which should be on the filter, with 25 c.c. 

 water. It gives a stronger diff'erential 

 coloring of the tissues than Ranvier's 

 picro-carmine ; but overstaining must be 

 carefully avoided. For sections hardened 

 in alcohol or with Kleinenberg's picro- 

 sulphuric acid, two to five minutes are 

 sufficient; for bone, etc., decalcified with 

 picric acid, less time ; for Muller's fluid 

 specimens considerably more time is re- 

 quired. The fluid stains fibrous connec- 

 tive tissue deep red ; striped muscle dull 

 red ; smooth muscle, blood, and horny 

 tissues bright yellow ; glands reddish - 

 yellow. In the kidney it gives difterential 

 colorations of the various portions of the 

 tubules. 



It gives a quite sharp nuclear colora- 

 tion, but produces less contrast between 

 the nucleus and the protoplasm than does 

 Ranvier's picro-carmine. It is, however, 

 easily made equal and equivalent to the 

 latter by adding very dilute ammonia to 

 the picric acid over solution until it begins 

 to assume a rich wine-red shade, which is 

 quite distinct from that of the acid solution. 



— The October number, of the Journal 

 of Microscopy and Natural Science (vol. 



