852 RECORD OF CURRENT RESEARCHES RELATING TO 



The difficulty of the investigation was ouhanccfl by tlic smallncss of the 

 spinal ganglia ; making use of fresh specimens, which were separated 

 into small pieces in consequence of the fact that gold chloride does not 

 infiltrate through any great depth of tissue, and choosing especially the 

 caudal end where the muscular layer is thin, and the mass of fatty cells 

 feebly developed, or carefully separating off the muscular portions, or, 

 still better, by removing the nervous portions by dissection of the 

 animal, the author placed them in solutions of gold chloride J per cent. 

 or ^ per cent, strong ; 1 per cent, solutions were also used, but the 

 best results were obtained with tlie ^ per cent, solution. Thenco 

 the specimens were removed to Pritchard's reducing fluid, formed 

 of one -pavt of formic acid with one of amyl-alcohol and 100 of 

 water, where they remained for twenty-four hours exposed to the 

 light. The preparation, which would be now of a dark purple-red 

 colour, was removed to Konigstein's macerating fluid, containing 50 

 parts fuming hydrochloric acid and 35 i^arts water and 15 parts glyce- 

 rine. Twenty-four hours' maceration made the jireparation much 

 darker and separated it into small pieces ; removed to glycerine to be 

 rendered transparent, these were, after twenty-four hours, fit for 

 inspection. 



Dealing with the " essential " characters in the structure of the 

 spinal ganglia, Herr Freud points out that the cells of these structures 

 become arranged in two distinct layers, of which one belongs to the 

 dorsal and one to the ventral branch, and it is in the latter that we 

 find a smaller number of larger cells as a general rule. Varying in 

 arrangement and in compactness as they ajipear to do at first sight, 

 we soon learn that the spinal ganglia always present certain types, and 

 that these types reappear at definite points, so that the spinal ganglion 

 of a certain segment has the same " physiognomy " in all animals. 

 There are but two essential elements in a spinal ganglion — nerve-cells 

 and nerve-fibres ; the former vary in number from eight to twenty- 

 three, but from ten to sixteen is the most common nximber ; they are 

 of three sizes, but the medium forms are the most usual ; their form 

 is spherical or ellipsoidal, and their contours are well marked ; they 

 are, with scarcely an exception, bipolar, for those which are ordinarily 

 regarded as unipolar are merely modifications of the others. It is 

 interesting to compare this observation with that of Dr. Beale, whose 

 knowledge of this subject is probably unequalled—" There are no 

 apolar cells and no unipolar cells in any part of any nervous 

 system." 



The author deals in detail with the fibres of the ganglion, which 

 are found to vary greatly in size, and passes on to " Details of the 

 Structure of the Spinal Ganglia," " Remarks on the Relation of the 

 Spinal Ganglia to the Dorsal Medulla," " On the Origin of the 

 Roots of the Nerves and on the Dorsal Medulla and pia mater." 

 The paper, which is illustrated by four jjlatcs, extends over eighty 

 pages. 



AmcBboid Epithelia.* — Professor Graber, of Czernowitz, adds 

 another to the list of cases in which amoeboid movements have been 

 * ' Zool. Anzeiger,' ii. (1879) p. 277. 



