664 SUMMARY OF CUBRENT RESEARCHES RELATING TO 



lateral space. At first siglit it might be thouglit that we had here to 

 do with two modified polyps, but the simple undivided endodermal 

 axis shows conclusively that there is only one. The author thinks 

 that the cells in which the attacking-granules are developed have a 

 gi'eat resemblance to the dermal glands seen in many Ccelenterates, 

 and he regards the granules, which, like the stinging-capsule, only act 

 once, as being secretions. 



In the gelatinous tissue of the umbrella of Grambessa mosaiJia, 

 V. Lendenfeld observed granular filaments which appeared to be of a 

 nervous nature, and which were certainly in connection with the 

 cnidoblasts, and probably with the sensory epithelium. In other 

 words, we here meet with a cnidocil which does not work mechanically, 

 but under the influence of a stimulus conveyed through the fibre ; the 

 protoplasm of the cnidoblast has here the form of a closed tube, the 

 regular contraction of which would act on the sides of the capsule and 

 cause the protrusion of the filament. 



In teased preparations of Cyanea annasJcala the author has fre- 

 quently observed cnidoblasts, the centripetal processes of which are 

 connected with ganglionic cells of the subepithelial layer. These 

 processes are not hyaline but granular, and their protoplasm does not 

 differ in character from that which surrounds the urticating capsule 

 and lies around the nucleus. 



It appears to be very probable that there is a continuous connection 

 between the nervous system and the protojdasmic covering of the 

 urticating capsule, which, therefore, is acted upon by the pressure 

 which the covering exercises upon it. In Cyanea annasJcala there is, 

 in addition, a small stellate body, which passes through the integiunent 

 of the distal pole. In Physalia muscular fibres are developed in the 

 protoplasm. The contraction of the protoi)lasm is brought about by 

 a stimulus from the nervous system, which is comparable in its action 

 to a reflex action ; in addition, however, there is evidence of the 

 possession by the nervous system of an inhibitory influence. 



The author concludes by expressing his conviction that the 

 cnidoblasts must be looked upon as unicellular dermal glands. 



Observations on Medusae.* — Dr. O. Hamann's first essay deals 

 with the development of the generative organs of the Discomedusfe, 

 as to which w'e have as yet only the scattered observations of Claiis and 

 the Hertwigs on mature forms. The author has been able to make 

 some observations on Nausithoe punctata, a representative of a sub- 

 family of the Ephyridfe. 



In the Ephyrula-stage of Nausithoe, in which there is only one 

 gastric filament in each interradius, we may detect the first rudiments 

 of the generative organs ; there is a thickening of the gastric 

 epithelium of the subumbral wall of the stomach. Soon a distinct 

 supporting lamella is developed, into which the ova migrate, and 

 within the saccule a cavity is develoi^ed ; where the gastric epithelium 

 forms the wall of the saccule the cells have a palisade-like arrangement. 

 "With regard to the testes we find that the cells which lie in the centre 



• Zeitschr. f. Wis8. Zool., xxxviii. (1883) pp. 419-29 (1 pi.). 



