On the Connection of Nerves and Chromohlasts. 287 



nuclei, four or five times longer than wide. They are filled with 

 very small black granulations. The outlines are ill-defined. 

 Their substance fixes carmine with great energy. The nervous 

 bundles of the fins present only a very small number of those 

 fibres, but they may be followed when isolated, during a very long 

 course, as shown in the Figure. They may be recognized in this 

 case by their continuity, for the fineness of those elements is extreme, 

 and at the same time, by the presence on their course of nuclei 

 sometimes near and sometimes remote from one another. Some- 

 times the fibre seems to grow wider in order to contain the nucleus, 

 and at other times the latter seems to be thrown oft' laterally, in a 

 kind of floating membrane. It must not be forgotten that we speak 

 here only of the specimen prepared according to our directions. 



Without asserting here the existence of a direct relation be- 

 tween the nervous fibres and the chromohlasts, we will limit our- 

 selves to a statement of the residt of our researches. The ques- 

 tion is a very diffictdt one to solve, owing to the nature of the 

 sarcodic element, which is usually recognizable by its granulations, 

 but is for that very reason impenetrable to the eye, so that all 

 observation must be summed up in investigating the continuity of 

 a nervous fibre, characterized either by its length, and the physical 

 pecuharities of its substance, or better, by the presence of its nuclei, 

 with the sarcodic substance, without any hope of tracing the ner- 

 vous fibre into the midst of the contractile element. 



An auxiliary, however, presented itselfj which might help to 

 determine this continuity. The granulations of pigment given up 

 by the expansions of the chromoblast, may in their contraction 

 become an excellent ipoint de repere. Let us suppose that every 

 appearance indicates the continuity of the sarcodic substance and of 

 the nervous fibre ; this appearance will become almost a certainty, 

 if, on the course of the nervous fibre, in the neighbourhood of the 

 chromoblast, we discover granulations of pigment which have 

 evidently been given up by the sarcodic extensions returned on 

 themselves. "We have endeavoured to represent all the cases of 

 this kind that we have been able to meet. 



As the inquiry regards parts which had not been dried, but 

 were observed in situ in the thin lamina which extends from one 

 ray of the fin to the other, the relations observed between the 

 parts can only be natural. If the instances are so rare, it is first 

 because the continuity which we try to observe exists in a plane 

 perpendicular to the visual one, and secondly because only a small 

 number of chromohlasts show themselves in a state of isolation 

 favourable for observation, even in the case which we bring for- 

 ward ; we have not thought it right to dissemble the considera- 

 tions which might plead against an appearance evidently conform- 

 able to the theory, but the demonstration of which we shall not, 



