Miscellaneous. 153 



nervous system as a circulatory apparatus. But a nervous sj'stem 

 is not a hollow organ capable of being injected, and the imputation 

 seems to have been made a little inconsiderately. The discussion 

 not having related to the Accela I do not know how far my results 

 may apj)ly to the Planarise injected by M. Blanchard ; but in all a 

 sheath seems to exist around the nerves, and if the contiguous 

 lacunae also existed, we should have in them a natural explanation 

 of all the difficulties, and the proof that the mistake has not been 

 entirely on the side of the French zoologist. — Comptes Rendas, 

 July 20, 1885, p. 256. 



The Nest of the Fifteen- spined SticJdehacJc. By Prof. Kael Mobius. 



Among the fishes of the Bay of Kiel the sea-stickleback (Spina- 

 cliia vulgans, Elem.) is distinguished by the remarkable instinct of 

 constructing a nest for its eggs and young. For this purpose it 

 employs delicate plants which grow in the shallow water, and masses 

 these upon Zosterce or the fronds of seaweeds which wave below 

 the surface of the water or on the piles of landing-stages, until they 

 form a soft rounded mass of 5-8 centim. in diameter. In this nest 

 the female, in May or June, deposits several masses of ova, and the 

 male surrounds the nest with white silky threads and then keeps 

 watch by it. 



All this has long been known, but exact knowledge of the con- 

 stitution of the threads and the place of their origin has hitherto 

 been wanting. The examination of male sea-sticklebacks in May 

 and June 1884, enables me to state that the threads are usually from 

 0']2 to 0*13 millim. in diameter, and consist of several cords stuck 

 together, which, again, are composed of very fine parallel threads. 

 The substance of which they are composed is nitrogenous, and is a 

 peculiar modification of mucine, as appears from its behaviour to- 

 wards various acids and alkalies. It is formed in the kidneys of 

 the male, and, indeed, in the epithelial cells of the urinary canals, 

 which exert this form of activity only at the time of reproduction, 

 and during this period behave towards staining reagents in the same 

 way as the muciferous organs of other Yertebrata. 



The kidneys of mucus-bearing sea-sticklebacks are inflated, 

 especially at their posterior extremity. Prom the kidneys the 

 mucus passes through the ureters into the bladder, which is thereby 

 dilated into a large pyriform vesicle, from the opening of which the 

 mucus finally oozes out as a white thread-forming mass and attaches 

 itself to solid objects that it touches. A male stickleback from the 

 urinary aperture of which mucus protrudes therefore needs only to 

 move around the nest in order to spin round the masses composing 

 it and the adherent ova. — Schriften naturwiss. Vereins fiir Schleswig- 

 Uolstein, Band vi. Heft 1, 1885. 



