518 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Embryonic Tentacular Knobs of certain Physophores.*— While 

 investigating the anatomy of the tentacixlar knobs of several genera of 

 Calycophores, Mr. J. W. Fewkes was struck by their close resemblance 

 to the " embryonic knobs " of Agalma. 



If the terminal filament of the Calycophore knob be reduced to 

 nothing, we have left a tentacular appendage homologous with the 

 embryonic knob of Agalma, Phjsophora, Agalvwpsis and other Physo- 

 phores. This resemblance seems to the author to have a genetic 

 significance, and to indicate a relationship between two great groups 

 of Siphonophora, called the Physophorte and Calycophorse. In order 

 to strengthen this supposition he was led to search out other re- 

 semblances in the larvfe in which these structures are found. The 

 result was that an interesting likeness between the single ("em- 

 bryonic") nectocalyx of Monophyes and the "primitive scale" of 

 Agalma was found. The following reasons led him to regard these 

 last-mentioned organs as homologous. Both are formed in the same 

 way, both are embryonic and are lost in subsequent development. 

 Wo 'have in the "primitive scale" of Agalma an indication of the 

 point in the development of the Siphonophora, where the separation 

 of the Physophorfe from the Calycophorae, or where the separation of 

 both groups, from a " stem-form," took place. The embryonic bell 

 of Monopliyes is an organ of motion ; the primitive scale of the young 

 Agalma, although homologous to a bell, has lost the function of motion, 

 and is an organ of flotation; while in Agalmopsis (Halistemma) the 

 embryonic bell is not even represented. The only structure in the 

 larva oiAgalmopsis (Halistemma), which shows the relation of this genus 

 to the Calycophorie is an embryonic tentacular knob, like that of the 

 larva of Agalma, which is thought to be homologous to the tentacular 

 appendage of the Calycophores. This statement of a possible genetic 

 relationship between these two groups is not held to apply to the 

 Pueumatophorfe (" Pneumatophoridse " Chun), nor to the Discoidese. 



Blue Colouring Matter of Rhizostoma.t — E. Blanchard has a 

 note on his own investigations into the blue colouring matter of 

 Bhizostoma cuvieri, in which he points out the difierences between his 

 results and those lately obtained by Kleinenberg on the same body ; 

 one which the latter author distinguishes as cyanein. The French 

 observer finds that the tissues give up the colour after death, and that 

 the blue colour of the aqueous solution disappears when heat of from 

 40° to 45° is applied, and gives place to a well marked rosy hue, 

 which, again, disappears on cooling. Spectroscopic examination 

 reveals the presence of three absorption-bands, one in the red, one in 

 the yellow, and one in the green region ; the second of these corre- 

 sponds almost exactly in position to the sodium-band. If the aqueous 

 solution is treated with ammonia the blue colour is immediately pre- 

 cipitated under the form of small blue flakes which may be collected 

 on the filter-paper and analyzed. The author hopes that further 

 investigations will reveal the cause of the difierences which obtain 

 between his results and those of Krukenberg. 



* Amer. Natural., xvii. (1883) pp. G67-8. 



t Bull. tSuc. Zool. Fiaucc, vii. (188a) pp. 402-^. 



