ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 625 



have a framework which is firmer than the inclosed homogeneous fluid 

 material which is regarded as the true contractile substance. 



Peripheral Nervous System of Amphioxus.* — Dr. E. Fusari has 

 used in the study of the peripheral nerves of Amphioa:us the chloride of 

 gold aud potassium method recommended by Golgi ; he has been able to 

 demonstrate the presence of a sympathetic nervous plexus and of 

 branchial nerves. A branch of the dorsal spinal nerves divides, when 

 it reaches the peritoneum, into two branches ; one branch, the sym- 

 pathetic, is distributed to the '^ eritoneum itself; the other passes upwards 

 and comes into relation wi^l the branchiae. 



By a careful study of the details of the cutaneous nerves the author 

 has been able to find the cause of the divergences of opinion which have 

 been expressed regarding them. The arrangement difiers in diff'erent 

 regions ; on the skin of the back and the lateral regions it is quite 

 exceptional to find anastomoses between two nerve-trunks, while on the 

 skin of the abdomen they are so numerous that we may almost say that 

 this region forms a true plexus. In the latter, also, there are ganglionic 

 cells in the nodal points, and there are small ganglia formed of two 

 nerve-cells. The final ramifications of the cutaneous nerves are very 

 delicate fibrils, which, in chloride of gold preparations, appear to end 

 freely. In very fine sections some filaments may be seen to traverse the 

 cuticle which supports the epidermal cells. The author agrees with 

 Langerhans in believing that there is a direct connection between the 

 nerve-endings and the ej)ithelial cells. 



The branchial nerves may be seen to ramify on the external membrane 

 which invests the branchial apparatus ; the plexus thus formed is very 

 delicate at some points, and has a general resemblance to those which 

 are often found among the pseudojDodia of Amcehse. Two types of 

 ramification are distinguished in the sympathetic branches. 



With regard to the first two pairs of nerves which have by some 

 authors been regarded as comparable to the fifth pair of cranial nerves 

 in other vertebrates, in consequence of their jDossession of what have 

 been considered to be ganglia, the author states that these bodies are 

 formed of one to four cells, from which one, two, or even three nerve- 

 fibres are given ofi"; they may consequently be regarded, in correspond- 

 ence with the views of several anatomists, as peripheral ganglia. 



Role of the Accessory Nuclear Body in Secretion.t — Herr G. 

 Platner has investigated the histology of secretion in the pancreas of 

 chelonians, lizards, snakes, and amphibians, comparing the phenomena 

 there observed with those seen in the Malpighian tubes of insects. 

 Accessory nuclear bodies (Nebenkerne) are constant in the pancreas of 

 reptiles and amphibians and in the above-mentioned tubules. With the 

 appearance of secretion-globules in the protoplasm, a remarkable nuclear 

 activity is associated. By a process of nuclear budding, not to be 

 confused with division, an accessory body is formed, which seems to be 

 an eliminated surplus of nuclear material, and to have a genuine 

 secretory significance. In the secreting cells there may be only one 

 accessory body or several ; according to their age these exhibit more or 

 less trace of nuclear characteristics ; finally they undergo retrogressive 

 metamorphoses and disappear. 



* Arch. Ital. Biol., xi. (1889) pp. 237-42. 



t Arch. Mikr. Anat.. xxxiii. (1889) pp. 180-92 (1 p].). 



