376 Miscellaneous. 



Nevertheless I am Ptnick \nth this circumstance, that the nigose 

 Corals, with a tctramoral type, arc hardly ever found, except in the 

 transition-rocks : they therefore preceded the secondary Corals of the 

 hexaraeral type, just as in the embryos of our living Actiniir we sec 

 appear 4 and theu 6 tentacles. The history of the organisms on 

 the surface of the earth consequently resembles the development of 

 an existing animal. 



Some species of the Actinicc seem to be reproduced with the 

 greatest facility by means of little fragments abandoned by the foot. 

 I have ascertained this process of multiplication in all the indi- 

 viduals of Sarfartia pelluc'ula* that I kept in captivity in 1872 and 

 1874. Dicquemare discovered the strange fact in Mftriduim dian- 

 thus. 



Spontaneous scissiparity is, on the contrary, the most common 

 mode of propagation in Sagartia ignea. I have observed it also in 

 Ancmonia sulcata f. It never takes place in Sagartia effcta, and in 

 many other species which I have examined. The tendency to scissi- 

 parity and to reproduction by means of the fragments of the foot 

 would have nearly the value of a specific character. — Comptes 

 Eendus, November 23, 1874, p. 1207. 



Action of Liglit on the Development of the Young of Frogs. 



M. Thury took the eggs of Eana temporana and placed them all 

 under precisely the same favourable circumstances, except that while 

 part received light through colourless glass, another part received 

 it through green glass. The former developed rapidly, and by the 

 end of Alay had a length of four centimetres, and well developed 

 hind legs in most of them ; while the latter were slowly developed, 

 blackish in colour, hardly had a length of two centimetres by the end 

 of May, and were without a trace of the hind legs. By the 10th of 

 June the former had their fore legs and some were changed to frogs ; 

 the latter, still black, had no trace of legs, and breathed almost ex- 

 clusively by means of their gills. By the 1.5th of July all the 

 former had become frogs ; but those of the latter still had no legs, 

 and by the 2nd of August they were all dead without a trace of legs' 

 having appeared. Some of the young of the latter lot, transferred to 

 the vessel of the former on the loth of July, finished their metamor- 

 phosis. At the same time some of the former transferred to the 

 vessel containing the latter continued to develop, showing the in- 

 fluence of the first impulse in their development. — Ulnstituf.'Dcc. 23, 

 1874. 



* On the 23rd of August, 1872, a Sagartia pellucida abandoned about 

 ten fragments of the foot ; on the 2.5tJi of August they became rounded ; 

 on the 5th of September one of them bore 8 tentacles; on the 7ih. of 

 September the same fragment presented 15 or 10 tentacles. 



X On the 18th of September, 1874, an Ancmonia mdcata divided spon- 

 taneously, brought together its divided intef,ainients ; on the 21st of 

 Septemlier the new-formed disk spread out, and the rudiments of the new 

 tentacles were seen ; on the 28th of September there were 20 tentacles. 



