30 GEOEGE JOHN EOMANES 1875- 



P.S. — I should have said that neither gold nor 

 silver brings out any nervous tissue. 



Medusa muscle is not doubly refracting, but then 

 none that I have here seen is striated, and unstriated 

 muscle is not doubly refracting anywhere, is it ? 



Dunskaith : June 24. 



Many thanks for your long and suggestive letter. 

 The poisons also are most acceptable. I have 

 waited before writing to try effect of the latter, but 

 the weather has been so stormy that no jelly-fish 

 could be got. 



The most interesting observations I have made 

 since writing before are the following. Unmutilated 

 Sarsia in a dark room seek a beam of light thrown 

 into the bell-jar containing them, and this as keenly 

 as do moths. But when the so-called eye-specks are 

 cut out, the animal no longer cares for light. 



I have only come across two species of luminous 

 Medusae — both, I believe, as yet undescribed — and in 

 these the light is emitted from the margin alone, and, 

 with electrical stimulus, is strictly confined to the 

 intra-polar regions, being strongest at the two 

 poles. 



There is no doubt at all about the muscular 

 nature of the fibres we saw. In the larger kinds of 

 Medusae (the covered-eyed) these fibres are much 

 coarser, and are clearly seen to be arranged in con- 

 centric bundles, having four or five fibres in each 

 bundle. Alternating with these bundles, and about 

 the same width as these, are strands of undifferen- 



