30 SUMMARY OF CURRENT RESEARCHES RELATING TO 



8. The nervous fibres, both those of the proper substance of the 

 cornea and those of its epithelium, always terminate in two ways, 

 namely, by plexus or reticulation and by free ending. The latter 

 mode, when occurring within the cornea, takes place not only in the 

 branching cells but also withiu or between the fibrous laminfe. 



9. The axis-cylinders of the corneal nerves are made up, like the 

 fibres of striated muscle, of fibrils, each of which consists of minute 

 particles and of a peculiar intermediate substance which unites them 

 in linear series ; in this case these particles are round, whereas in 

 muscle they are prismatic. 



Influence of Food on Sex.*— The results of experiments detailed 

 by E. Yung tend to confirm those previously obtained by G. Born,f 

 who found that when young tadpoles were subjected to special kinds 

 of food (in one case vegetable food being given, in another mixed 

 vegetable and animal), a large preponderance of females were deve- 

 loped. In these experiments there was an absence of what forms the 

 chief normal food of tadpoles, viz. — marsh-slime, containing various 

 organic detritus, rotifers, infusoria, diatoms, &c. 



Yung reared the tadpoles of Bana esculenta in four vessels, feed- 

 ing the broods respectively on fish, meat, coagulated egg-albumen, 

 and egg-yolk. The percentage of females in each case was 70, 75, 

 70, and 71. In a fifth vessel, out of a brood of 38 tadpoles nourished 

 simultaneously on meat, algae, and white of egg (without slime), 30 

 were females, six males, and two doubtful. These results seem to 

 demonstrate that the quality of the food experimented with exercised 

 no distinct influence on the sex, but that a special diet given to young 

 tadpoles from the time of hatching favours the development of a 

 female genital gland, as Born concluded. 



B. INVERTEBRATA. 



Mollusca. 



Digestion of Amyloids in Cephalopoda.:}: — E. Bourquelot in 

 attempting to resolve the contradictory statements that have been 

 made with regard to the preseuce of a diastatic ferment in the liver of 

 the Cephalopoda, finds that the quantity of starch which is altered 

 varies with the condition of the individual. When it is starving the 

 action is slow and difiicult to detect, for the gland is then in repose ; but 

 when digestion is going on in the animal the change is almost instan- 

 taneous. As in mammals, ruptured starch-grains are alone acted on. 

 It is somewhat curious, the author thinks, to find this ferment in car- 

 nivorous animals, but its presence affects the discovery of the possible 

 glycogenic function of the Cephalopod's liver. Can glycogen and 

 starch-ferments exist in the same gland ? as yet there is no proof of 

 the presence of sugar in livers that have been properly treated, but, as 

 the author justly remarks, in physiological chemistry an experiment 

 yielding negative results should be frequently and carefully repeated. 



* Comptes Eendus, xciii. (1881) pp. 854-6. 



t See this Journal, i. (1881) p. 874. 



X C«mptes Rendus, xciii. (1881) pp. 979-80. 



