406 SUMMARY OF CUERENT RESEARCHES RELATING TO 



ordinary goblet-cells : — (1) In the former no stoma could be detected, 



(2) nor appendages like the stalk or the basal process of the latter ; 



(3) in the goblet-cells the nucleus always lies (in the unstalked 

 types) close to the base of the theca, in Leydig's cells it generally 

 lies centrally, distant from the membrane; (4) on the external 

 surface of the smooth thecal wall in the goblet-cells those markings 

 were never apparent which are characteristic of Leydig's cells, those 

 namely which were long since described by Langerhans as rib-like, 

 and which have been interpreted by Flemming as the expression of 

 intercellular bridges; (5) the goblet-cells empty their contents by 

 the stoma, and are to be regarded as unicellular glands, while the 

 fxmction of Leydig's cells still remains doubtful. 



Mucous Threads of the Sea-stickleback's Nest.* — Prof. K. Mobius 

 has traced to their origin the mucous filaments which bind together 

 the nest of the marine stickleback (SpinacMa vulgaris Flem.). 



The mucinous substance, whose chemical characteristics are de- 

 scribed, is formed from the epithelial cells lining the canals of the 

 kidney. Some of these epithelial cells are at the time of mucin- 

 production even morphologically modified — the nucleus becomes flat 

 and retreats to the base of the cell. The product which first appears 

 in the meshes of the cell-network is not stained by hsematoxylin 

 (mucogen), but this is changed from within outwards, first into 

 granular and then into hyaline mucin. After the mucin is excreted 

 the cell-nuclei disappear and the cells degenerate and probably 

 perish. Prof. Mobius compares the micro-chemical and histological 

 changes of the mucin-producing cells with Heidenhain's general 

 theory of the differences between actively secreting and quiescent 

 glandular cells, and indicates the relative interest of his observation. 

 He notes the probably similar origin of the nest filaments of Chiro- 

 nectes pidus, and suggests that the pathological " fibrin-cylinders " in 

 human urine may possibly have a similar history. 



He also indicates the possible evolution of the instinct ; a state 

 of renal hypertrophy is associated with reproductive functionality in 

 the testes, the enlarged kidneys cause an abnormal pressure, from 

 which the stickleback tries to relieve itself by rubbing against foreign 

 objects, to which the squeezed-out mucin adhered. At this time, 

 however, he is in close company with the female and near the bunches 

 of eggs glued to water-plants ; there, therefore, he found the nearest 

 and most convenient place for getting rid of the burdensome mucin, 

 and thus became a nest-spinner. 



y. General, f 



Geographical Distribution of Pelagic Marine Animals.J — Herr 

 C. Chur ascribes the wide distribution of pelagic forms to four 

 causes ; they are of great geological age, and existed long before the 

 elevation of the continents, while the appearance of the latter has 

 given rise to currents which are of great significance in distribution ; 



* Arch. f. Mikr. Anat., xxv. (1885) pp. 554-63. 



t This section is limited to papers which, while relating to Vertebrata, have 

 a direct or indirect bearing on Invertebrata also. 

 X Zool. Anzoig., ix. (1886) pp. 35-9, 71-5. 



