404 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 



Miiller may be easily studied, and it is then evident that they 

 represent axis -cylinders, as Miiller supposed. 



3. On Freezing aiyplied to Histology. — Axel Key and 

 Retzius C Nord. Med. Arkiv.,' 1874, No. 7) find that if fine 

 sections of frozen tissues be hardened before thawing, so that 

 the tissues remain in the state they have assumed by freezing, 

 they are generally pierced by a number of holes, fissures, and 

 canals. Thus, in tendon there are longitudinal canals; in the 

 skin, fissures and holes ; in brain, spinal cord and liver, 

 numbers of lacunae and wide spaces traversed by trabeculse. 

 Precisely similar appearances are presented by sections of 

 frozen blood, gelatine, and starchy matters. On following 

 the process of congelation under the microscope they found 

 that, at the moment of freezing, the water, in separating 

 from the organic matter (brain, blood, or starch), forms 

 branched acicular columns of ice w^hich spread in various 

 directions. If the mass be now hardened by alcohol or osraic 

 acid, the spaces occupied by the ice remain as canals and 

 cavities. If it be thawed, the mass becomes confused as it 

 softens, so that the canals may be easily mistaken for normal 

 structures. It follows that conclusions must only be drawn 

 with the greatest caution from frozen objects, and never 

 Avithout verification by other methods. Still, freezing has a 

 real value in certain cases, e.g. for transverse sections of deli- 

 cate membranes, and some other objects in the fresh state. 



II. The Cell in General. — Development and Proliferation 

 of Epithelia and Endothelia. — Zielonko has studied, under 

 Recklinghausen's direction, the growth of the cornea and 

 other tissues detached from their normal situation. We 

 must defer a notice of this important paper (' Archiv f. 

 Mikr. Anat.,' x, 351). 



III. Blood. — 1. Oti the value of High Pozvers in the Diag- 

 nosis of Blood-stains. — Dr. Joseph Richardson ("American 

 Journ. Med. Sci.,' July, 1874) advocates the measurement of 

 the corpuscles from suspected stains by means of a micrometer 

 eye-piece and high powers ri-50th or l-25th immersion lens). 

 He finds that by this means it is easy to distinguish with 

 certainty stains produced by human blood from those of 

 sheep's or ox blood. The method was successfully applied 

 by Dr. Richardson in the following cases : — Prof. Reese and 

 Dr. Weir Mitchell furnished him each with three packages of 

 dried blood from stains made by sprinkling the fresh fluid 

 from an ox, a man, and a sheep, upon white paper ; the two 

 series were simply numbered 1, 2, and 3, and each gentleman 

 preserved a memorandum of the kind of blood composing each 

 sample. Dr. Richardson then proceeded as follows : — Small 



