380 Analytical Notices of Books. 



those vessels which proceed from the heart appear, it is said, to possess 

 proper coats, the capillary canals in which the blood becomes venous 

 offering no trace of a proper vascular membrane. It may be added that 

 the two systems seem, both from the description and figure, to pass 

 immediately into each other. 



We may also notice in this place, although properly belonging to 

 another subdivision, the paper which follows by the same author, " Ueber 

 " die Jfais diaphana und J^ais diastropha mit dem Nerven-und Blut- 

 " system derselben." It forms an interesting addition to the little 

 knowledge which we previously possessed respecting these minute and 

 paradoxical .Annelida. Dr. Gruithuisen states that he has never observed 

 in the Xaides any other mode of propagation than that by subdivision ; 

 and thus confirms the observations made by Trembley and Roesel, and if 

 we recollect rightly by Mviller also, that they are capable of artificial 

 multiplication by cutting their bodies transversely into distinct portions, 

 which had been doubted on the authority of Bosc and others. The 

 nervous system is in Nais diaphana (which is synonymous with J^ais 

 vermicularis, Auct.) more developed than the apparently simple structure 

 of its other organs would have led us to expect ; in J^^ais diastropha, a 

 new species, it is apparently much less complicated. The author assures 

 us that the effect of this difference is strongly marked in the different 

 degrees of sensibilit}' and volition evinced by the two species. For the 

 details of the nervous system, as well as of the vascular, we must refer 

 to the paper itself. 



The Dissertation "Ueber eineigenthiiniliches, d^n J^ervus Sympathicus 

 " analoges, Nervensystem der Eingeweide bei den Insecten," by Dr. 

 Johannes Miiller, contains a further development of the analogy between 

 the nervus recurrens of insects and the nervus sympatheticus of higher 

 animals. The anatomy of this, which he regards as the proper intestinal 

 nervous system of insects, had already been given by the authour from a 

 species of Phasma in a previous volume of these Transactions. In the 

 present it is extended to numerous other Orthoptera, as well as to insects 

 of most of the remaining orders. From these observations Dr. Miiller 

 is clearly of opinion that the identity of the nervus recurrens with the 

 ganghonic system, as it is called in Fertebrata, is clearly made out, and 

 that there can be no doubt of its representing the nervus sympatheticus 



