Miscellaneous. 481 



granules are intensely stained by the blue colour, the vitellus is 

 perfectly colourless, and that it is impossible to consider these 

 granules as vitelline elements, since the methylene blue solely 

 affects chromatin in an active condition, as we have already stated. 



Conclusions. — 1. In the first stcKjes of development in the dace the 

 blastoderm-cells exhibit no individualized chromatin, and the kanjo- 

 Jcinetic figures are exclusively formed of achromatic elements. This 

 important fact furnishes support to the opinion which the most 

 recent researches tend to make the prevalent one, namely that in 

 the cell the essential role does not belong to the chromatin, as was 

 formerly believed, but must rather be ascribed to the ceutrosomes. 



2. The chromatin at first exists in a diffused condition in the 

 protoplasm, as certain authors have stated. It becomes differentiated 

 and individualized in this protoplasm in the form of (jranulations 

 which can be stained by means of reagents ; then it becumes incorpo- 

 rated into the nuclei to constitute the equatorial ■plates which are absent 

 in the first staqes, — Comptes liendus, t. cxvii. no. 1 (5, October 16, 

 1893, pp. 521-524. 



On the Cerebral Nuclei of Myriopods. 

 By M. Joannes Chatix. 



It is well known how much interest attaches at the present time 

 to the study of the elements of the nervous system in Invertebrates. 

 By putting into precise form the results thus obtained by zoological 

 histology, and contrasting them with the facts revealed by histogeny, 

 we shall succeed in elucidating and interpreting exactly the compa- 

 rative structure of the nervous tissue, with respect to which so 

 many points still remain obscure or imperfectly understood. 



One of these points is the notion of the cerebral nuclei, ganglionic 

 nuclei, &c., which have been stated to occur in the Articulata, 

 and especially in the class Myriopoda, where, in the accounts of 

 various investigations, mention has been made under this name of 

 elements which are represented as formations of a special character 

 and of high functional value. It is, however, only necessary to 

 compare these descriptions in order to prove that they apply, in the 

 respective cases, to different elements, the importance and inde- 

 pendence of which henceforth become somewhat doubtful. 



Since, therefore, it was imperative that the subject should be 

 re-examined in a rigorous fashion, I undertook with this object a 

 series of researches which were devoted especially to various species 

 of the group Chilopoda (Lithobius forficatus, Scolopendra morsitans, 

 8cutigera coleoptrata, &c.). I purposely chose these types because 

 they had been mentioned as exhibiting the cerebral or ganglionic 

 nuclei with exceptional distinctness. 



Ann. (& Mag. N. Hist. Ser. 6. Vol. xii. 36 



