590 RECORD OF CURRENT RESEARCHES RELATING TO 



submitted to the same current, at a temperature of 2° ; 45 minutes 

 elapsed before the nuclei became apparent. 



(2) Somewhat similar experiments were undertaken with eyes 

 from a frog, which were respectively submitted to a temperature of 

 33° and 80°, together with an electric current ; in the former the 

 nuclei appeared within an hour after the experiment ; in the latter 

 not at all. 



(3) The cornea of a frog was submitted to an induction current 

 sufficiently strong to kill the cells, and was then kept for two hours 

 in a damp chamber at a temperature of 33° ; it was then found that the 

 nuclei were broken up into fragments or small spherical granules. The 

 action in this case appears to have been that the currents broke up the 

 nuclei, and the work thus commenced was completed by "autodigestion." 



Coalescence of Amoeboid Cells into Plasmodia.*— The coagulation 

 of the perivisceral fluids or the blood of Invertebrata as studied in 

 the air-tight chamber presents, as Mr. Geddes shows, some significant 

 phenomena. Thus the amoeboid corpuscles of the earthworm's 

 perivisceral fluid, those of the gill of Pholas, the corpuscles of 

 Patella and Buccinum, during coagulation become aggregated into 

 groups, which rapidly become individualized, and themselves send 

 out pseudopodia. 



Of the two kinds of corpuscles possessed by Pagurus, the 

 elongated, coarsely granular ones do not possess this power, which 

 however belongs to the finely granular ones, which may enclose the 

 former kind in their clot ; the same distinction is observed in Carcinus 

 mcenas and Cancer pagiirus. The corpuscles, with their looped 

 pseudopodia, of the common starfish send out pseudopodia, as in the 

 previous cases, from a united mass. The Echinoidea, as exemjilified 

 by Echinus sph(era, show the phenomenon most strikingly. The clear 

 perivisceral fluid contains coarsely and finely granular corpuscles 

 similar to those of Paguriis, besides coloured ones. The clot com- 

 mences as a cloudiness of the liquid ; the cloud gradually becomes 

 denser until a small brown pellet is the result. This is formed 

 entirely of the finely granular corpuscles which run first into small 

 heaps, these uniting into larger ones until a large mass is formed 

 containing the nuclei and granules in an endoplasm, and sending 

 out generally filamentous pseudopodia from a hyaline ectoplasm 

 which is clearly differentiated from the former ; the pseudopodia 

 sometimes lengthen to an immense extent. 



A comparison of these cell-formed clots with those of the Myxo- 

 mycetes appears to demonstrate a true homology between them ; and 

 the possession of the same power by the Ehizopods, Microgromia, 

 Bhaphidiophrys, PJionergafes, &c., shows it to be at any rate a very 

 widely spread function of amoeboid cells. 



Structure and Development of Dentine. t — M. Magitot gives a 

 short account of his investigations on this structure, which have led 

 him to the conclusion that it is not, as some writers— Duvernoy e. g. — 



* 'Proc. Roy. Soc.,' xxx. (1880) p. 252, and 1 plate, 

 t ' Couiptes Rcndus,' xo. (1880) p. 1298. 



