330 JOHN BEARD, 



wise mentioned or figured, may be named. Thus Burckhardt ^ 

 figures large ganglion- cells in the tail of Triton taeniatus. These un- 

 doubtedly belong, although the author failed to notice their evanescent 

 nature, to the transient system. Like Rohon, he considers that they 

 correspond to the "Hinterzellen" of Freund in Petromyzon. 



In one of his recent memoirs His figures, without further com- 

 ment, one of the large transient ganglion-cells of the trout. Also 

 Retzius^), whose figure is from a "Golgi" preparation. In the text 

 the latter author remarks "was die Zelle der fig. 4 betrifi"t, so habe 

 ich sie wiedergegeben, weil ich solche grosse rundliche Zellen mehr- 

 mals an demselben Platz antraf; welcher Natur diese Zellen sind, ist 

 mir unklar geblieben." 



Further, in the new edition of Kölliker's "Handbuch"^) there 

 is a brief description of Rohon's observations, followed by extracts 

 from a letter from von Kuppfer to the author in which the former 

 states his ability to confirm the transient nature of these cells and 

 their occurrence, as was quite to be expected, in Acipenser sturio. 



The occurrence of a double row of these cells on the spinal cord 

 of Petromyzon embryos is briefly mentioned by C. von Kupffer *). 



There are still two other publications of value which doubtfully 

 belong to the literature under consideration. 



Of these Fritsch's well-known observations ^) on the really giant 

 ganglion-cells of Lophius need only be mentioned at this juncture. 

 At a later period his discoveries would call for consideration. 



Strasser's memoir ^) contains an account of my own observations, 

 together with a number of theoretical considerations. His paper is 

 quite interesting, even although one may be at times unable to agree 

 with his conclusions. 



Since the above was written. Prof, von Kupffer has published 

 observations on the transient ganglion-cells of Petromyzon in Heft 2 

 of his "Studien zur vergleich. Entwicklungsgesch. des Kopfes der 

 Cranioten." This memoir has not as yet reached my hands, and his 

 results are only known to me from a brief summary by Froriep in 



1) No. 4. 



2) No. 12, p. 29 and tab. 14, fig. 4. 



3) No. 8, p. 172-173. 



4) No. 9, p. 31 — 32. — A similar observation in Petromyzon was 

 recorded by myself in 1889 (No. 2, p. 117). 



5) No. 6. r 



6) No. 15." 



