250 Cytologie und Befruchtung. 



sieve tube into the threads , Converting them into 

 „slime strings". The ferment action also extends to the 

 surrounding ceUulose, Converting it into callus; and the pectic 

 middle lamella is simüariy converted into the „median node''. 

 Cases are also considered in which the protoplasm seems to 

 be more directly concerned in the production of callus. The 

 view as to the importance of ferment action in originating in 

 the sieve tubes, is borne out by the formation of the sieve 

 plates abutting on the albuminous ceils. 



The question as to whether there is a real open com- 

 munication betwixt adjoining sieve tubes is not conclusiveiy 

 answered, though the slime strings are credited with a trans- 

 locatory function. 



Precise details as to the methods employed in the investi- 

 gation are not given. J. B. Farmer (London). 



Chamberlain, Charles J., Methods in plant histology. 



8^ Vi, 159 pp. 74 figs. Chicago (The University of Chicago 



Press) 1901. ^ Doli. 1.50. 



This work has grown out of courses in plant histology given 



by the author, not only to his classes at the University of 



Chicago, but also by correspondence to non-resident students. 



The lectures were published in the Journal of Applied 



Microscopy and later elaborated and enlarged into the 



present form. 



About one third of the book is devoted to general directions 

 as to apparatus, reagents, the most improved methods of 

 fixation, embedding, sectioning, and staining. The chapter on 

 apparatus is brief and discusses only the simplest apparatus 

 necessary to produce good results. The chapter on reagents 

 puts in convenient form for reference the few formulae now 

 recognized as essential in modern microtechnique. Stress is 

 laid on proper killing and fixation. Much of the material 

 intended for critical work is allowed frequently to undergo 

 changes that render it unfit for study before killing and fixing 

 is attempted. In view of the fact that improper and delayed 

 fixation is responsible for much poor m.orphological work, the 

 advice to „take the killing and' fixing fluids into the field" is 

 timely. 



The chapter on general method gives a füll account of the 

 paraffin method, little space being given tö the celloidin method. 

 The relative value of the two methods is tersely expressed by 

 the Statement: „Use celloidin as a last resort." 



Among stains, Delafield's haematoxylin, Haidenhain's 

 ironalum-haematoxylin, cyanin, and erythrosin, and safranin- 

 gentian violet-orange combination are given preference. The 

 method of using the last named combination differs somewhat 

 from that of Flemming in that the gentian violet and the 

 orange are allowed to act for a shorter period than the time 

 given in his formula. 



