ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 425 



Amount of Dissolved Oxygen in Water required by Young 

 Salmonidse.* — D. NoelPaton fiuds that a fall in the amount of dissolved 

 oxygen in water to below one-third of the normal amount, 2 ccm. per 

 litre, is prejudicial and generally fatal to young Salmonoids. Wheu 

 the surface of the deoxygenated water is exposed to an atmosphere con- 

 taining oxygen, the fish frequently seem able to live by constantly 

 coming to the thin layer of more oxygenated water at the surface. 

 Some individuals ate able to sustain life for very prolonged periods in 

 water containing only minimal traces of dissolved oxygen. Such fish 

 are seen to lie very quietly at the bottom of the bottle. 



Action of Spurge on Salmonoid Fishes.f — H.M.Kyle has studied 

 the fatal effect of Euphorbia hiberna on fishes — an effect well known to 

 the Irish peasantry. The plant cut into small pieces and pounded with 

 stones, or simply trampled upon at some convenient spot on a river, 

 forms an emulsion in the water which, being swept downward into the 

 pools, carries death to all fishes in its course. Even in small quantities 

 the spurge extract is almost as fatal as corrosive sublimate. 



Chemical analysis of the extract shows tannic acid, about 1 p.c. it 

 has been calculated, but on this estimation the spurge extract is fatal 

 within a shorter time than a corresponding quantity of tannic acid. 

 Hence the percentage of tannic acid has been under-estimated, or some 

 other substance or substances in the extract also aid in producing fatal 

 effects. 20 p.c. of the fresh extract is fatal within 5 minutes, whilst 

 - l p.c. takes 4-6 hours, and seems to be the smallest percentage that 

 has fatal results. In the case of fishes death is considered to ensue 

 from the inflammation of the gills and consequent stasis of the circu- 

 lation. 



Electrical Properties of Nerves.J — V. Grandis communicates the 

 results of 150 experiments, which go to show, if we understand aright, 

 that a nerve is to be regarded rather as a dielectric than as a conductor. 



Function of the Thyroid Gland.§ — E. Koos tries to combine the 

 two views, (a) that the thyroid produces and exudes a special substance, 

 and (b) that the thyroid acts as a neutraliser of auto-toxins. 



By its iodothyrin, the thyroid increases the renal elimination of solid 

 uric-substances, which accumulate in myxcedema when the thyroid has 

 degenerated. Tetanus, after extirpation of the thyroid, is due to a 

 retention of these uric substances. Tetanic convulsions correspond to 

 ursemic cramps. Normally, the thyroid secretion antagonises the uric 

 poisons. But this is only a hint of a learned lecture. 



European Wild Cattle. || — B. Lydekker sums up an interesting dis- 

 cussion by noting that the aurochs and the Pembroke and park cattle 

 belong to one and the same species, and since the latter do not appear 

 specifically separable from the domesticated cattle of Scandinavia, which 

 probably formed the type of the Bos taurus of Linnaeus, it is clear that 

 the aurochs has no right to a distinct species name. Instead of Bos 

 primigenius, it should be called Bos taurus primigenius. 



* Proc, R. Soc. Edin., xxiv. (1902) pp. 145-50. 

 t Proc. K. Soc. London, Ixx. (1902) pp. 48-66. 

 j Atti Accad. Sci. Torino, xxxvii. (1902) pp. 341-6. 

 § Ber. Nat. Ges. Freiburg, xii. (1902) pp. 119-33. 

 i| Knowledge, xxv. (1902) pp. 100-2. 

 August 20th, 1902 2 w 



