510 J\IiticeUaneous. 



plasm of the filaments, while the extraiiuclear filaments, drowned 

 in protoplasm, must be very difficult to distinguish. And it may be 

 observed, in fact, in such cases as that of the Geryonidie, in which 

 the vitellus is almost entirely composed of a protolecyth which pos- 

 sesses a power of refraction very different from that of the proto- 

 plasm, that tlie extranuclear filaments are almost as distinct as the 

 intranuclear filaments. The difiertuce between these filaments is 

 only apparent, and depends on the proiDerties of the substance that 

 surrounds the rays of sarcode. 



The small granules or bacilli which, according to M. Eiitschli, 

 appear in the middle of each of the intranuclear fibres are in my 

 opinion only inflations or varicosities of those filaments. I have 

 never seen them united into a lamella, as described by MM. Wtras- 

 burger and Van Beneden. M. Elitschli has shown that these infla- 

 tions divide, and go to unite with the centres of attraction which 

 are now represented by aggregations of protoplasm the bulk of which 

 increases rapidly ; if these varicosities only showed themselves upon 

 the intranuclear filaments, they would constitute a remarkable dif- 

 ference between the two kinds of filaments. But this is not the 

 case. In the ova of the Geryonidce, which are not very compact, 

 and even in the much denser ova of the Echini, we can distinguish 

 U2)on the extranuclear filaments varicosities which have hitherto 

 escaped the notice of all observers. Tliese inflations are more elon- 

 gated and less regular than those of the interior of the nucleus ; 

 but nevertheless they are indubitable varicosities, which move like 

 the others and pass slowly to amalgamate with the central aggrega- 

 tion of protoplasm. 



This aggregation, therefore, is not exclusively a derivative of the 

 substance of the old nucleus, either by its mode of formation or 

 by its mode of growth ; it is a result of the fusion of a portion of 

 that substance with a part of the protoplasm of the vitellus. M. E. 

 van Beneden considers the new nuclei to be composed of two pro- 

 nuclei — one derived from the old nucleus, the other from the surroimd- 

 ing vitellus. In the cases observed by me there are no distinct pro- 

 nuclei, but a direct fusion between these substances of diverse origin. 



The reagent which best shows all these filaments is, in my opinion, 

 picric acid followed by glycerine. Osmic acid, employed by M. 0. 

 Hartwig, causes the extranuclear filaments almost to disappear; 

 hence the mvich too exclusive importance ascribed by him to one of 

 the systems of filaments. What this naturalist describes as the 

 nuclear Jihre is an artificial product, resulting from the action of an 

 ammoniacal liquid. 



As regards the relations of the central aggregations with the new 

 nuclei, I have often observed that these aggregations, after having 

 absorbed the greater part of the radial filaments and their varicosi- 

 ties, present clearer and probably more liquid spots than the rest 

 of the mass ; this is why I previously describecl them under the 

 name of vacuoles. The new nucleus is the result of the fusion of 

 these vacuoles ; and what remains of the central aggregation consti- 

 tutes the envelope of the nucleus. Erequently, but not always, we 

 see a vacuole originate, not in the central aggregation, but in an 



