1867.] 



On the Muscular Nerves of Tipula. 



61 



genian region; it was repeatedly compared with the nebula by several 

 persons, and we believe therefore that it was quite accurate. It is 

 not now an exact representation of the nebula as it exists, conse- 

 quently there seems to be strong evidence of change. 



The observations were continued by Mr. Hunter from 1860 to 1861i, 

 and by me to the present time. A drawing was made by Mr. Hunter 

 while he was assistant, and it has been verified by me in almost all its 

 details, and extended considerably. In one place, where there is a dis- 

 agreement between Mr. Hunter's drawing and mine, Mr. Hunter had 

 previously been under the impression that some change was going on. 



The nebula, when nearly on the meridian, was examined with the 

 6-feet instrument and with the 3-feet instrument, before and after that 

 time. The appearance of the nebula differs from night to night, as the 

 faint details come out more or less perfectly in the different states of 

 the atmosphere ; but the drawing represents it as seen on the best 

 nights. 



The present drawing contains many new stars, some laid down by 

 the micrometer, and others by eye estimation. The nebula has been 

 traced to a distance of fully 40' North, and about the same distance 

 South of the trapezium, on the following side to a distance of about 

 30', and to a much greater distance on the preceding side. 



As to resolvability, the brighter parts contain a great number of 

 minute stars, generally of a reddish colour. "With the spectroscope 

 three I right lines were seen, but there was no certain evidence of a 

 continuous spectrum. The results arrived at by means of the spec- 

 troscope do not, however, appear to be at variance with our observations 

 on resolvability, as even if the whole nebula were to consist of minute 

 stars, the continuous spectrum produced by them would still be ex- 

 tremely faint. 



XII. "On the apparent relation of the Nerves to the Muscular 

 Structures in the Aquatic Larva of Tipula ci^ystallina of De 

 Geer.^' By Richard L. Maddox, M.D. Communicated by 

 Dr. Sharpey. Received June 18, 1867. 



(Abstract.) 



To avoid as much as possible errors that might be attributable to a 

 faulty mode of examination, the figures and photographs have all been 

 made from the larviB alive, and in their natural medium, except two 

 instances in the drawings and one in the photographs. After alluding 

 to the effects of various reagents which were generally found useless in 

 " differentiating" the fine nervous structures, and the ordinary mode of 

 branching in the nerves from the ganglionic chain, two particular 

 methods of termination are selected as illustrative of the relation be- 

 tween the muscular and nervous tissues. One, termed the " flabeliiform," 



