Miscellaneous. , 355 



scarcely reacli the level of the second disk. — Comptes Rendus, Feb- 

 ruary 21, 1881, p. 420. 



On the Circulation and Respiration of the Ophiuridae. 

 By M, N. Apostolides. 



Having had at my disposal numerous living Ophiurans in the 

 laboratories of RoscofF, the Sorbonne, and Port Vendres, I have 

 been able to apply to these animals peculiar processes of fine injec- 

 tion ; and these processes have furnished me with novel results, 

 which I have the honour to communicate to the Academy. My in- 

 vestigations have been made upon the following species : — Ophiura 

 texturata, Lam. ; Opluura albida, Forbes ; Ophiocoma granulata, 

 Jiliformis, and neghcta, Forbes ; and Ophiocoma rosida, Johnst. 



1. After a successful injection of the aquiferous system, on dis- 

 secting the interbrachial space of the madreporic plate, we come 

 upon a dilated Avhitish canal, rendered rigid by calcareous plates ; 

 and on tearing this canal we see, towards the middle, a brownish 

 inflated mass, the supposed heart of authors, on the side of which 

 there is a fillet containing the injected material. This fillet is the 

 sand-canal. This experiment, frequently repeated upon different 

 species, shows that the sand-canal becomes injected at the same 

 time as the aquiferous system, and that the supposed heart is inde- 

 pendent of that system ; further, the particles of injected material 

 found outside the madreporic plate prove that the sand-canal, ex- 

 tending from the aquiferous ring to that plate, establishes a direct 

 communication between the aquiferous system and the exterior. 



2. " The heart is tJve true centre of the circulation . ... it is p. 

 plexus of anastomosing vessels which unites the two rings, oral and 

 aboral." It is thus that M. H. Ludwig defines the structure and 

 function of the heart. With regard to the two rings, at the discovery 

 of which he arrived by coloratioji with haematoxyline, he admits that 

 he knows " neither their contents nor their structure." 



The organ called the heart presents very various stiuctures and 

 relations. By a careful dissection it is easy to see that it has an 

 elongated form, and is produced into a rectilinear canal going to 

 the madreporic plate ; an injection, forced into the brown mass 

 which represents it, immediately fills this prolongation and appears 

 on the outer surface of the madreporic plate. Its structure, when 

 studied in a heart taken from a living animal, shows that it is a 

 gland with a proper excretory canal opening outward, and not an 

 organ of circulation. On each side of this hitherto misunderstood 

 gland we see two small fibrous bauds, directed laterally towards 

 the base of the arms ; they become vividly coloured by haematoxyline, 

 like the analogous bands which sustain the Polian vesicles ; but 

 the liquid injected into the heart never went in their direction. 



3. An injection forced between the integument and the digestive 

 tube (that is to say, into the general cavity) never shows itself ex- 

 ternally, and never penetrates into the aquiferous system. The 

 general cavity is therefore entirely closed ; it is formed of a widened 

 portion surrounding the digestive tube (peristomachal space), which 



