280 Journal of Applied Microscopy. 



but without allowing the temperature to rise above 20" C. The sum of the light, 

 heat, and chemical energy should form a constant which produces the desired 

 changes in the gold solution. Diminution of one form of energy may be com- 

 pensated by increase of another, although strong daylight is an essential. The 

 reaction may be divided into two parts, the penetration of the gold chloride, and 

 the action of the light upon the tissue. The tissue becomes opaque "under the 

 action of the reagent, consequently it must be a membrane, or consist of line 

 libers, or be cut in thin pieces. ' As a rule objects are exposed to the light in 

 the acid for at least eight hours in cool weather, and six hours in warm weather. 

 Only occasionally in winter are objects left longer than twenty-four hours in the 

 acid. The gold chloride may be left in the light as long as there is no organic 

 matter in it. Organic matter causes a precipitate of metallic gold which weakens 

 the solution. Long objects immersed in the fluid must be fastened at both ends, 

 and membranes must be expanded and fastened, preferably, to glass rings which 

 will allow free action of the light. The membranes should not be stretched too 

 tightly. The reaction is accelerated by the access of the oxygen of the air. On 

 this account the tissue may be floated on the surface of the liquid during reduc- 

 tion, or it may be placed in moist chamber, where the acid may be reduced 

 from time to time. e. m. h. 



Buehler, Dr. A. " Structure of Nerve Cells. ^^'^^ author gives a minute description 

 Verb. Phys. Med. Ges. Wuerzburg, 31: 1898, of the spinal ganglion cells of a variety 

 PP- - 5-392- ^j types. A granular meshwork is pres- 



ent, in the interstices of which it is easy for fluid to circulate, and food can come 

 and waste go out. The framework is associated with central corpuscles, and 

 flbrils linking one ganglion cell to others are differentiations of this cell sub- 

 stance as paths for stimuli. The fibrils spread out in the cell are ultimately 

 connected with the cell as a whole, both mechanically and physiologically. Each 

 element of the cell is influenced by the others, and nervous function is the result 

 of their united cooperation. 



This author does not speak of any differentiation into two kinds of systems, 

 such as Arnold shows in his work, but both pieces of work help to show the com- 

 plexity of the protoplasmic structure in cells. a. m. c. 



Kolossow, Prof. A. Intracellular Connections I" this work evidence is brought to 

 in Epithelium. Archiv. Mikr. Anat. 52: 189S, show that epithelial cells are organi- 

 PP' '"'-^' cally connected, instead of being merely 



cemented, as is usually supposed to be the case in epithelial tissue. The bridg- 

 ing is a constant structure and suggests the demonstration is not possible, that 

 extra cellular bridges are of importance in glands and epithelium generally, espe- 

 cially as paths for the passage of stimuli from cell to cell, as well as useful for 

 merely mechanical purposes. A- ^i- ^■ 



In work done previously to this, no ob- 

 Assheton, R. Uevelopment of the Pig during • 1 i_ 



the first ten days. Quart. Journ. of Micro, servations have been made on speci- 

 Sci. New Series No. 166, Nov. 1898, pp. xii^XiS younger than twelve to fourteen 

 "520-361, 4 plates. , , , , , ■ 



days ; the author succeeded m gettmg 



a number varying in age from four days to eleven days, covering the earliest 



