34 SUMMARY OF CURRENT RESEARCHES RELATING TO 



markedly in April ; and (5) the sleep is more profound at the beginning 

 than towards the end of winter, — the quantity of carbon used up in- 

 creasing from November to April. 



Marine Intoxications and the Life of Burrowers.* — G. Bohn has 

 some interesting observations and suggestions on this subject. He has 

 shown that sea-water in which red Algas (especially Lithotliamnium) have 

 been living is "very toxic (alkaline), while that which has filtered through 

 the sand is not." Burrowing animals have chemical as well as mechanical 

 protection. 



We are unable clearly to understand Bohn's somewhat too terse 

 sentences in regard to burrowing Crustaceans, where the respiratory 

 current is reversible. The auimals are said to dispose their anterior 

 appendages in such a way that the entrant currents filter through the 

 sand, and to return to the direct current when external poisons or their 

 own excreta begin to reach the gills, which thus act as organes 

 avertisseurs. We hope that a less condensed memoir will give a full 

 account of the actual procedure. 



The author goes on to discuss Arenicola marina and other burrowing 

 Annelids. The lobworm in its vertical burrow, and Pectinaria in its 

 tube, produce ascending (inverse) and descending (direct) currents of 

 water by active and successive dilatations of the segments of the middle 

 region of the body. By altering its position or the direction of the 

 muscular wave, the exceedingly sensitive worm averts the external 

 alkaline intoxication. Yet at the end of August circulatory troubles 

 begin in the gills and skin ; there is an autumnal intoxication ; leuco- 

 cytes accumulate around the vessels ; phagocytosis sets in ; the skin is 

 ruptured near the parapodia (such as they are) and the nephridial 

 orifices. One of the consequences of histolysis is the escape of the ova. 



Breeding Habits of Ameiurus nebulosus. t — Dr. A. C. Eycleshymer 

 has made some observations on the nesting and spawning of this 

 American catfish, both in natural and artificial conditions. In natural 

 conditions the egg-mass is laid in shallow water under logs or stumps, 

 or even in old pails, pieces of stove-pipe, and so on ; it is first watched 

 by both parents, but later only by the male. Where, as in artificial 

 fish-ponds, objects which may serve as shelters are absent, the fish exca- 

 vates deep holes, in which the eggs are deposited. Both sexes appear 

 to take part in the process of excavation. 



Axolotl and Ambly stoma. * — Prof. H. L. Osborn describes various 

 axolotls obtained from different regions, and makes some remarks on the 

 relation of the two forms. He distinguishes between the primary and 

 the secondary adult characteristics. The acquisition of the first in- 

 volves radical morphological changes, and these changes take place in 

 all forms, whether terrestrial or aquatic. The secondary characteristics 

 are largely points connected with the external anatomy, and instead of 

 always taking place pari passu with the primary changes, may occur 

 later, or not at all. The author distinguishes three types of develop- 

 ment : — the amblystoma, where primary and secondary changes occur 

 simultaneously ; the siredon, where the secondary changes take place later 

 than the primary ; and the axolotl, where the latter never occur at all. 



* Comptes Rendus, exxxiii. (1901) pp. 593-6. 

 t Amer. Nat., xxxv. (.1901) pp. 911-8. % Tom. cit., pp. 8S7-903 (G figs.). 



