ME. G. J. ROMANES ON THE LOCOMOTOR SYSTEM OE MEDHS2E. 
309 
greater was the resistance which it offered to such passage. Therefore, in view 
of the fact that the physiological connexions only appear to be certain so long as the 
connecting portions of tissue are not narrowed down below a certain point, Dr. Eimer 
concludes in favour of a nervous plexus pervading the contractile tissues rather than 
in favour of the functional homogeneity of these tissues. He observes, however, very 
justly, that if such a plexus is present, its fibres must be capable in a high degree of 
vicarious action. Dr. Eimer states further, that the amount of tissue which proves 
sufficient to maintain physiological continuity between any two almost severed parts 
differs in different portions of the umbrella. 
The paper concludes with several theories as to other possible functions which the 
lithocysts may have to subserve as well as that of locomotion, e. g. respiration and 
nutrition ; but as these theories are not supported by any observations or experiments, 
it seems unnecessary to adduce them here. It therefore only remains to state that 
Dr. Eimer has satisfied himself as to the presence of nerve-cells and fibres in the region 
of the lithocysts, and that in his experiments upon excision of the contractile zones in 
Cyancea capillata he obtained results which were perfectly conformable with those which 
he obtained in the case of Aurelia aurita. 
I have entered thus at length into the contents of Dr. Eimer’s paper, because, as my 
work was throughout independent of his, it becomes the more important to state clearly 
the points in which we agree and the points in which we differ. It is a matter of 
satisfaction to me that, while the latter are but of subordinate interest, the former are 
throughout the more important. 
First, then, as to the mere matter of priority, it may be well to state that, as Dr. 
Eimer’s work was done in September of 1874, I have a right to claim precedence, 
both as to observation and publication of what I have termed the fundamental experi- 
ment. On the other hand, Dr. Eimer has the right to precedence in the case of all his 
other observations. I shall now consider these observations seriatim ; and if I appear 
to give undue prominence to the points in which I differ from Dr. Eimer, it is only 
because I thus hope to secure a still more perfect agreement in our future papers. 
It will, of course, have been observed that Dr. Eimer’s view as to the exact seat of 
spontaneity in Aurelia aurita does not coincide with mine. He is careful to state that 
the ganglionic function is distributed all round what he terms the “ contractile zone,” 
i. e. the crescent-shaped interruption of the margin in which the lithocyst, together 
with its gelatinous hood, is situated (see Plate 32). On the other hand, I have stated it as 
my opinion that the lithocyst is alone the locomotor centre ; and notwithstanding the 
account which Dr. Eimer gives of the experiments by which he sought to localize that 
centre, I still adhere to this opinion. Dr. Eimer’s experiments in this connexion were 
twofold : — 1st, that of progressively lessening the amount of contractile tissue left 
adhering to an excised segment of Aurelia aurita ; and 2nd, that of excising the lithocyst 
without injuring the “ contractile zone.” Of these two methods Dr. Eimer appears 
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