1337 





JOHNS [OPK NS 



UNIVERSITY CIRCULARS 



Published with the approbation of the Board of Trustees 



VOL. X. No. 88.] 



BALTIMORE, MAY, 1891. 



[PRICE, 10 CENTS. 



MORPHOLOGICAL NOTES. 



FROM THE BIOLOGICAL LABORATORY OF THE JOHNS HOPKINS UNIVERSITY. 



EDITED BY WILLIAM K. BROOKS, PH. D., PROFESSOR OF ANIMAL MORPHOLOGY AND DIRECTOR OF THE CHESAPEAKE 



ZOOLOGICAL LABORATORY. 



On the Structure and Development of the Gono- 

 phores of a certain Siphonophore belonging to the 

 Order Auronectae (Haeckel). By W. K. BROOKS and E. 



G. CONKLIN. 



Among the specimens brought by the U. S. Fisli Commission Steamer 

 Albatross (1887-88) from the Pacific and left with us to be studied was a 

 single specimen of a SiphoiiOjihore, which is probably identical with the 

 genus Rodalia, described by Haeckel in his " Challenger " Report. The 

 interest in this form is the greater since Haeckel regards it as so unlike all 

 other Siphonophores as to necessitate its being placed in an entirely new 

 order, which he calls the Auronectae, or Siphonophores with an Aurophore. 

 But a few specimens, and those badly broken, have ever been obtained, and 

 this fact has led Claus, 1 among others, 2 to donbt whether Haeckel was jus- 

 tified in describing these few fragmentary specimens as the type of a new 

 order. The specimen here described was taken off the Galapagos Islands, 

 in latitude 46' south, longitude 89 42' west, and like all the previously 

 described specimens of this group, is badly mutilated, though in an excel- 

 lent histological condition. 



The present paper has to do merely with the structure and development 

 of the gonophores of the specimen mentioned, an account of the remaining 

 organs being reserved for a future communication. 



Haeckel says of the gynophores, or female gonophores : 3 " The female 

 gonophores are much more varied in shape and composition than the 

 androphores. They are easily distinguished from them by their more 

 rounded (usually pear-shaped) form and their longer stalks. There occur 

 the following remarkable variations : 



"A. Monovone Oynophores. Each female medusome develops only a single 

 large ovum." 



(1.) "The gynophore develops a single very large ovum surrounded by 

 a double envelope ; the inner envelope is the thin manubrial wall contain- 

 ing a smaller or larger blind spadicine cavity, sometimes a network of 

 irregular spadicine canals ; the outer envelope is the umbrella of the 

 medusoid person, with four narrow radial canals and a small distal ring 

 canal connecting the latter; this is probably the normal and most frequent 

 form of the ripe gynophore." 



1 C. Glaus, "On the Organism of the Siphonophora," etc. Ann. and Mag. Nat. Hist., 

 Vol. 4, and Arb. Zool. Inst., Wein, Bd. 8. 



2 J. Walter Fewkes, " On Angelopsis," etc. Ann. and Mag. Nat. Hist., Vol. 4. 



3 " Challenger " Report on Siphouophora, p. 295. 



(2.) "The same form but with four blind radial canals (reduced in the 

 distal half)." 



(3.) "The same form (as 1 and 2) but with eight equidistant, regular, 

 radial canals." Fig. 12, PI. II. 



(4.) "The same form (as 1 to 3) but with a variable number (five to ten) 

 of irregular, branched and anastomosing spadicine canals." 



(5.) " The same form (as 1 to 4) but without radial canals in the reduced 

 mil' f>lla." 



" H. Polyovone Gyiiopltores. Each female medusome develops an ovarium, 

 composed of a variable number of ovules placed in the wall of the modified 

 maniibrium. The umbrella seems to be usually reduced, very thin walled 

 without radial canals; often it has disappeared." 



(1.) "The gynophore is a medusome with rudimentary umbrella; the 

 spadicine canal (or the original gastric cavity of the medusa) is central, 

 straight, and runs in the axis of the manubrinm (PI. II, Figs. 9 and 10) ; 

 the ovules are regularly disposed around it." 



(2.). "The gynophore is a medusorae with rudimentary umbrella; the 

 spadicine canal is eccentric, curved and runs on one side of the manubrium ; 

 it embraces the ovarium as a crescent-shaped or semicircular blind canal." 



(3.) "The gynophore is a simple sporosac, the mauubrium without um- 

 brella ; the ovules are arranged equally around the central spadicine canal." 



(4.) "The gynophore is a compound sporosac, without umbrella; two 

 or three (rarely more, sometimes only one) buds developing from off the 

 outside of the primary manubrium (PI. II, Fig. 11). The buds or the 

 secondary sporosacs, contain either a single large ovum or a group of sev- 

 eral small ovules; they have usually a long pedicel, and its canal arises 

 from the base of the primary spadix. The different remarkable modifica- 

 tions of gouophores here enumerated exhibited in the adult spirit speci- 

 mens examined, showed no regular distribution, but occurred in very 

 variable number and association. A further accurate research on living 

 and well preserved specimens is required to make out their mutual rela- 

 tions and significance." 



Although a careful search was made for them, the audrophores or male 

 gonophores mentioned by Haeckel were not observed. It seems impossible 

 that they could have been overlooked, since they were carefully looked for 

 both in sections and in surface views of a large number of gonodenclra ; and 

 while female gonophores were found in every stage of development and in 

 great abundance, not a trace of an androphore could be found. The writere 

 therefore conclude that the specimens examined bear female gonophores 

 only. Professor Haeckel's description of the androphores occupies but 

 twelve lines, and he gives but three figures of them, all surface views and 

 very unsatisfactory. It would therefore seem possible, at least, that Pro- 



