454 M. Lacaze-Duthiers on the Sexes of the Alcyonaria. 



laris, Behryce mollis, Alcyonium pahnatum, A. digitatum, and 

 Paralcyonium elegans — in which there is no doubt that not only 

 the polypes, but even the zoanthodeinata are unisexual. 



The observations which form the subject of the present me- 

 moir, having been greatly multiplied throughout two consecutive 

 springs and summers, appear to have furnished certain results ; 

 nevertheless it must not be forgotten that it is very difficult to 

 assert absolutely that a large specimen, often containing several 

 thousand polypes, has not a single animal of a different sex from 

 that which appears to exist in it exclusively ; I must therefore 

 make every reservation with regard to any exceptions that may 

 present themselves. 



In order to ascertain the nature of the genital glands, we must 

 always commence by a microscopic examination and histological 

 investigation of the characteristic elements — that is to say, by 

 recognizing the spermatozoid and the ovum. This is the only 

 means of obtaining certain results, which may afterwards allow 

 us to judge rapidly of the sexes, on the condition, however, that 

 the productive organs of these elements, or these elements them- 

 selves, present such differences as may be appi'eciable by the 

 naked eye. 



When the ovum and the testes present at the same time the 

 same form and the same colour, it is impossible to distinguish 

 them without the microscope ; and in this case it will be under- 

 stood how laborious the observations become. But fortunately 

 this is very rarely the case, for almost always these elements 

 present some prominent differences. 



In Gorgonia subtilis, for example, the ova are of a splendid 

 carmine rose-colour, whilst the male organs are colourless : the 

 former are large, and rarely exceed two or three in number ; the 

 latter, on the contrary, are small, and form eight racemose 

 packets, each composed of ten capsules. This fact once ascer- 

 tained by the microscope, it is easy, by means of large incisions, 

 or even by simply tearing the sarcosoma with the nail, to dis- 

 tinguish the male and female zoanthodemata very rapidly. I 

 have very often done this without ever being deceived, although 

 the fishermen brought me specimens by hundreds. The observa- 

 tion of Gorgonia subtilis is so easy, and furnishes such precise 

 results, that it may serve as a type of researches of this kind. 



In the Muricece the ova have a bright colour, resembling that 

 of the sarcosoma ; the testicular capsules, on the contrary, are 

 very pale or nearly colourless. One of the species, M. placomus, 

 which abounds on the coralligenous banks of the Mediterranean, 

 is of a fine slightly yellow orange-colour, but without brilliancy ; 

 its ova are of the same tint, but their shade is redder, brighter, 

 and more brilliant ; its testes are sometimes nearly white, but 



