1004 SUMMAEY or CURRENT RESEARCHES RELATING TO 



observers. Finding that tliese bodies were present before the encyst- 

 ment of the larva, but had disappeared when the Cercaria was liberated 

 from its cyst, he concludes that these cells function in the encystment, 

 that the rods give the cysts greater solidity and power of resistance, 

 and that they are probably most characteristic of those Cercarise 

 which encyst exteriorly like those of Fasciola Jiepcitica and AmpJiistomum 

 suhclavatum. 



Deep-water Turbellarians of Lakes.* — Dr. O. E. Imhof records 

 the fact that a particular species of Turbellarian apparently agreeing 

 very closely with Mesostomum rostratum Duges was found in deep 

 water in numerous lakes in Switzerland. The same species occurs 

 also in several of the Austrian lakes. Another dendrocoel Turbellarian, 

 greyish black in colour, was found in very deep water in Lej Sgrischus 

 and Lej Carloccio ; it is briefly described. 



Development of Nemertines-t — Dr. A. W. Hiibreeht describes 

 briefly the development of Lineus obscurus. After the formation of the 

 gastrula a number of free cells are given off by epi- and hypoblast, 

 which wander through the blastocoel and are the commencement of the 

 mesoblast. The cubical epiblast cells become in several regions 

 palisade-like through multij)lication, and form the rudiments of the 

 four larval discs which subsequently are covered by a continuous 

 layer of the original epiblast. The brain and lateral cords are de- 

 veloped entirely from mesoblast cells. The proboscis grows back 

 above the intestine into the blastocoel ; its sheath is formed of 

 mesoblast cells. The blood-cavities arise in the blastocoel. The 

 sexual organs arise from a mass of tissue below the nerve-cords and 

 in contact with the spine ; they probably arise from the epiblast. 

 The body of the Nemertine has no body-cavity except the cavities 

 already mentioned, which arise from the blastocoel. 



Nervous System of Acoelomate Planarians and new Sensory 

 Organ of Convoluta Schultzii.| — M. Y. Delage describes the nervous 

 system of Convoluta SchuUzii in the following terms. Around the 

 otocyst there is a bilobate ganglionic mass which forms the chief 

 portion of the central system ; attached are two smaller masses which 

 lie about it connected with it by a pair of large connectives, and with 

 one another by a transverse commissure. The fibres found in the 

 centre of these masses are extremely fine, the cells, which are peri- 

 pheral, are best developed at the postero-inferior part of the chief 

 mass, and form a continuous layer around the otocyst. 



The peripheral system is formed by six parallel longitudinal 

 nerves and their branches ; they are situated immediately below the 

 layer of zoochlorellsB, and are arranged by pairs ; the trunks are 

 connected by transverse anastomoses, which are ordinarily more 

 numerous at a greater distance from the head ; at the lower end the 

 cords converge and form a plexus. 



In addition to the otocyst and the two pigment or eye-spots, 

 there is another sensory organ which its discoverer calls the frontal 



* Zool. Aiizeig., viii. (1885) pp. 434-5. f Md., pp, 470-2. 



% Comptes Kendns, ci. (1885) pp. 256-8. 



