420 NOTES AND MEMORANDA. 



The following are the results of M. Yung's observations : — 



The ganglionic masses and the commissures which unite them are 

 evidently sensitive throughout the chain ; the sensibility is the same 

 on the superior, inferior, and lateral faces. 



The roots of the nerves radiating from the chain are both motor 

 and sensitive, contrary to the classical opinion of Newport, Valentin, 

 Longet, &c. 



Each ganglion is a centre of sensibility and of motion to the seg- 

 ment of the body to which it belongs; but the sensibility becomes 

 " inconsciente " and the movements reflex when the ganglion is separated 

 from those which precede it. 



The sub-cesophageal ganglion is the motor and sensitive centre for 

 all the masticatory elements and the foot-jaws. 



The brain or supra-oesophageal ganglion is sensitive on all its faces, 

 contrary to what prevails among insects, whose brain, according to M. 

 Faivre, is insensitive. It plays the part of motor and sensitive centre 

 for the cephalic appendages (eyes, antennae). 



Each right and left side of the brain acts upon the corresponding 

 part of the body, and it is the same with the other ganglia of the 

 chain. There is no interlacing in the course of the nervous fibres. 



The removal of the brain causes the toppling movement forwards, 

 which arises from a want of equilibrium, resulting from the insensi- 

 bility of the cephalic appendages, and from the predominance of the 

 movements of the posterior members. 



The movements which continue after the total removal of the brain, 

 and which in certain cases have a character of spontaneity, are never 

 co-ordinated. 



The lesion of one of the lobes of the brain produces " mouvements 

 de manege " from the injured side towards the other. 



The brain is the seat of the will and of the co-ordination of 

 movement. It has no direct action on the movements of the heart. 



The movements of the heart are accelerated by electrical excitation 

 directed to the commissures of the oesophageal ring, whence the 

 current travels to the stomato-gastric ganglion and the cardiac nerve 

 (the nerve described by Lemoine). They are retarded by the electrical 

 excitation of the thoi'acic ganglia. 



Male Organs of the Decapodous Crustacea. — The new Zoological 

 Station at Trieste is already bearing good fruit, an example of which 

 is to be found in the long and elaborate paper on this subject, * illus- 

 trated by six plates, by Dr. C. Grobben. The state of science during 

 a long period is well illustrated by the fact that no one seems to have 

 taken any interest in the subject to which Dr. Grobben directs atten- 

 tion, between the time of Aristotle and 1750, about which time Fortius 

 and Von Rosenhof examined the male organs of the crayfish. 



A. Internal Organs. 



I. Position. In the Tlwracostraca the testes are always placed 

 superiorly to the intestine, and in all, except the Paguridce, between 

 this organ and the heart ; in the Stomapoda they are placed in the 



* 'Alb it. Zool. Inst. Wien-Triest,' i. (1878) 57. 



