82 



BOTANICAL GAZETTE. 



[March, 



BRIEFER ARTICLES. 



Continuity of protoplasm.— In demonstrating this very important 

 fact, Strasburger 1 directs the use of the strongest objectives, and, where 

 possible, immersion objectives. This at once puts it out of the reach of 



many laboratories, where the teacher is 

 thankful if he gets enough ordinary ob- 

 jectives. The information, therefore, 

 that protoplasmic continuity can be eas- 

 ily demonstrated, with very little ma- 



nipulation and very ordinary objectives, 

 ought to be helpful to many. The most 

 favorable object used is the secondary 

 cortex or " green bark " of dicotyledons. 

 Strasburger suggests the buckthorn, 

 Rhamnus Frangula ; Goodale mentions 

 any " dicotyledonous shrub or tree." In 

 most of these cases the connecting fibrils 

 are so delicate that the highest object- 

 ives areneccessary to demonstrate them. 

 But in the common buckeye the strands 

 which connect the plasmic bodies are so 

 large as to be satisfactorily seen with a 

 magnification of 250 diameters, and very 

 well studied with a magnification of 500 

 continuity ^protoplasm in secondary diameters, and in neither case is there 

 , ' an y necessity of using an immersion 



objective To repeat very briefly the method of preparing the speci- 

 men, and omitting all details that were found unnecessary, it is as 

 follow* , Use a buckeye twig about J to J inch in diameter (those a 



IZ ZT T"? ^ 8t); CarGfUlly SUCe ° ff the P eriderm «° « to ex- 



fmlrst th reen ; nmke " thiU tangential 8eCtion from this latter; 



mmerse this in an aqueous solution of iodine (or, better, iodine in a so- 



ment l^T" ^ } P*" " ^ br ° Wn ' which wil1 take but a mo- 

 rn waJ t h G T° n f ih ° r0U * h] y t0 remo ™ excess of iodine ; mount 

 rlZ d .'„« f^ r, V f F 8lJP PUt a dr ° P ° f eh ^^Y pure sulphu- 



draw this in r ° ? * f ^T (&h0Ut ?5 P6r Cent > «*&*™ «>id, and 

 lentv o w I! und « r - thoroughly wash the specimen by drawing 



fhe mount w^ ith , 1^ ( *5 ? Wy im ^^' -place the water of 

 worHas been / ^ f n u an , d ^ 8peCimen iS "«* to observe - » the 



Zoh s ' t " ,T y d ° ne ' eVen a l0W P0wer wil1 rev ^ the very 

 "?^M^^ crossed in every direction by proto- 



thorough™* ^ eMier * ,UP the 8ectl ™ direct.y into the , lllIric acid and then wuh 



