162 
MR, G. J. ROMANES ON THE LOCOMOTOR SYSTEM OE MEDUSA. 
ing that the last-mentioned memoir is of so masterly a character, I have this year 
thought it desirable to abandon my original intention of concluding this series of 
papers with the results of a systematic investigation of the histology of the Medusae. 
Entertaining not the smallest doubt as to the accuracy of the results which have been 
obtained by the laborious inquiry of Messrs. Hertwig, I felt that time would be more 
profitably employed in extending the lines of my physiological researches than in con¬ 
firming morphological work which, to my mind, did not stand in need of confirmation. 
Feeling thus that the histology of the Medusae in all its leading features had been, 
relatively speaking, exhausted, I this year devoted myself to continuing and con¬ 
cluding the physiological work with which I began. I may observe, however, that 
when opportunity again permits, I hope to investigate the histology of those species of 
naked-eyed Medusae on which I have mainly experimented ; for with the exception of 
Sarsia, these particular species have not as yet been submitted to microscopical exami¬ 
nation by any of the more recent observers. Should this investigation tend to show 
that the nervous tissues of these particular species present any peculiarities which have 
not been described as occurring in the numerous species of naked-eyed Medusae which 
have been so carefully examined by Messrs. Hertwig, I shall communicate the results 
of my investigation in a supplementary paper to the Royal Society 7 . But meanwhile 
I communicate this additional instalment of physiological results under the title 
“ Concluding Observations on the Locomotor System of Medusae.” Possibly enough in 
future years various questions concerning the physiology of nerve and muscle may 
arise, for the solution of which the primitive nerve and muscle tissues of the Medusae 
will afford valuable material ; but for the present, it seems to me, this paper will 
pretty well exhaust the physiology of these tissues, and for this reason I have given it 
a title which indicates that the series of communications of which it is a member may 
now be considered as closed. * 
I. STIMULATION. 
§ 1. Artificial Rhythm. — (a.) I shall devote the whole of this lengthy section to a 
full consideration of what in my previous paper I termed “Artificial Rhythm.” It 
will be remembered that in my previous paper this subject was alluded to in a foot¬ 
note, of which the following is a copy:—“ As the present communication was originally 
accepted by the Royal Society, there here followed a lengthy subsection on £ Artificial 
Rhythm.’ A condensed epitome of the main facts which were detailed hi that sub¬ 
section may be found in the already published abstract of this paper in the ‘ Pro¬ 
ceedings of the Royal Society.’ But as the new theory of ganglionic action, which it 
is the main object of this passage to disclose, appears to me a theory of sufficient 
* The effects of several poisons still remain to be investigated, and I have still in view a number of 
experiments which have not yet been carried out; but as it is uncertain whether the results of these 
further observations will be worth publishing, I have thought it desirable thus to indicate that the work, 
so far as it has now gone, may be regarded as a completed structure. 
