750 SUMMARY OF CURRENT RESEARCHES RELATING TO 



course of the affection the power of the muscles becomes considerably 

 affected. Such examples as did not become phosphorescent after being 

 inoculated remained in perfect health. Other Crustacea, including the 

 common Crab, have been rendered phosphorescent by the inoculation of 

 this microbe. 



Nervous System of Decapod Crustacea.* — M. L. Bouvier has 

 studied the Decapod Crustacea in an ascending order, and, as a result, 

 he comes to the conclusion that in a natural classification they would 

 not be all placed in this order. The fresh-water Astacid^, for example, 

 appears to be a side branch of the marine Astacidse ; the Thalassinidae 

 appear to be marine Astacidee which have sheltered themselves in the 

 sand, and have ended by giving rise to the Paguridse which take refuge 

 in shells and form the third term of another branch. So, again, the 

 Porcellanidse, and perhaps the Anomura, are chiefly connected with the 

 Galatheidse, and serve as the point of departure for the true Brachyura. 

 When the nervous system of the Macrura and Anomura is studied in 

 these three branches, we see that the nervoiis system presents its 

 maximum of condensation in the transverse direction in the " Salicoques " 

 which are placed at the base of the suborder; in the Astacidse this 

 condensation is much diminished, especially in Nephrons; finally, in 

 the Porcellanidse and Galatheid^, or the Paguridse and Thalassinidse, 

 this transverse dissociation becomes more and more marked. In the 

 Decapods, therefore, the concentration of the nervous system in the 

 transverse direction diminishes as we approach the Brachyura. 



This law is absolutely exact if the abdominal chain is considered ; it 

 is only relatively so if the thoracic ganglia are studied. But this 

 difference can be easily explained. As the nervous system is dissociated 

 transversely, it has a tendency to condense longitudinally. In the 

 thoracic region, as compared with the abdominal, the ganglia are larger 

 and more closely approximated, and the connectives which unite them 

 are consequently shorter. And we may say, generally, that the conden- 

 sation of the nervous centres and connectives in the longitudinal direc- 

 tion is inverse to that in the transverse direction ; in the longitudinal it 

 increases as we approach the Brachyura, and in the transverse it 

 diminishes. 



These statements are not true of other Crustacea or Arthropoda ; the 

 law is peculiar to the Decapoda, and may perhaps be of use in studying 

 the affinities of the constituent members of the group. 



In passing from the macruran to the brachyuran forms, an abdominal 

 ganglion becomes part of the thoracic mass, the ganglionic chain 

 shortens and is placed in the thorax, and this reduced chain enters into 

 close contact with the centres of the thoracic region. The Galatheidae 

 and Paguridae are at the first, tlie Porcellanidae at the second, and the 

 Crabs at the third stage. 



"Liver" of Carcinus msBnas.f — Dr. A. B. Griffiths describes a 

 number of chemical investigations which seem to show that the so-called 

 liver of the crab is pancreatic in function. 



Genital Organs of Thelyphonus.J — Herr J. Farnani has observed 

 that the male sexual organs of Thelyphonus asperatus undergo remark- 



* Ann. Sci. Nat., vii. (1889) pp. 78-lOG (1 pi.). 

 t Proc. E. Soc. Erlinb., xvi. (1888-9) pp. 178-81. 

 X Biol. CentiMlbi., ix. (1889) pp. ;-!7fi-82. 



