MINOR ABNORMALITIES— HERMAPHRODITISM 47 



the condition: (1) successive unicyclic {monocyclic Masterman 150); (2) successive multicyclic 

 {poll/cyclic Masterman); and (3) synchronous. To the first group belong those fish which, like 

 Myxine, ripen only sperm when young and afterwards only eggs; to the second, those which are 

 protandrous in each season ; and to the third, those in which the ripening of both kinds of sexual 

 products takes place at much the same time in each period of breeding. 



True hermaphroditism,, abnormal. A very large number of instances have been recorded, chiefly 

 from the Teleosts. References to the more important of these will be found under the following 

 index numbers. 



Fuhrmann 71; Halbertsma 89; Hefford 90; Howes 101; Iwauzoff 105; Jiickel 107; 

 Jarvi 113; Johnstone 118; Kyle 135; Lowne 146, pp. 164-5; Luther 14.7; Martens, 149; 

 Masterman 150 ; Newman 167; Orlandi 177; Patterson 184; Poey 193; Sandman 214; 

 Schneider 218-9; Simpson 226a ; Smith 228-30; Smitt 881 ; Southwell 232 ; Stewart 235; 

 Vogt 265; Weber 268; Williamson 269-270. 



The limits of this work make short treatment of the present subject necessary, but certain of 

 the papers named above may readily be consulted for supplementary details. In particular, Weber 

 gives a valuable resume" of what was known on the subject up till 1884. Howes adds some 

 cases, and also initiates a very interesting discussion on the general questions involved. Stewart 

 contributes the solitary well-described instance in the Salmonidae, and an interesting example 

 in the mackerel. Masterman adds two cases, and continues the discussion begun by Howes. More 

 recently five other instances have been supplied by Williamson (269-270). Abnormal hermaphro- 

 ditism has now been recorded in examples of the Percidac, Squamipinnes, Sparidae, Scombridac, 

 Mugilidae, Gasterosteidae, Labridae, Gadidae, Plcuronectidac , Cyprinidae, Esocidae, Salmonidae, Clupeidae. 

 The condition seems also to have been recorded in Acipcnser, and among the Sclachii (see Howes 

 101, p. 543). 



Classification. Decisive evidence is not easy to obtain, but I believe that, on the whole, 

 abnormal hermaphroditism in Teleosts belongs to the third or synchronous type. The cases recorded 

 by Stewart (235) in the trout and mackerel were marked by the presence at the same time of fully 

 developed ova and sperm. No doubt various other recorded examples have shown apparent 

 protandry, and this circumstance, together with the fact that normally the females are larger than 

 the males, has led some authors to consider abnormal teleostean hermaphroditism as belonging to the 

 successive polycyclic type. It must be noted, however, in the case of many dioecious animals, 

 that during each season motile sperm is present abundantly in the testis of the male, months 

 before the contents of the ovary are fully ripe (e.g. sea-urchin, limpet, and other mollusca). The 

 argument regarding size is hardly relevant to cases in which the sexes are united. 



Structure. It will be remembered that in the majority of osseous fishes the ovaries are paired, 

 and that the ova when ripe dehisce into their central cavities, which unite posteriorly in a single 

 efferent duct. In the males also, the efferent channels, though frecpiently different in form, are built 

 essentially on the same plan. The Salmonidae, Muraenidae, Cobitis, and some others, are exceptional 

 in that the ova when ripe dehisce into the body cavity, from which they escape by means of oviducal 

 pores. In such fish, however, the males exhibit the typical arrangement as regards their efferent 

 ducts. 



In hermaphroditic conditions, very great differences in the relations of the two kinds of tissue 

 occur. For example : 



(1) One or more masses of spermatic tissue may be contained in, or attached to. some part of 

 one or both of the ovaries. In such cases the testicular ducts open into the cavity of the main gland 

 and are thereby placed in communication with the exterior. Or, mutatis mutandis, the converse 

 conditions may occur. The vast majority of the instances may be grouped in this division. 



(2) The gonad on one side may be entirely male and that on the other entirely female. The 

 gonads unite posteriorly just as two ovaries or two testes do, and their ripe products escape by one 

 genital aperture (cf. Williamson 269). 



(3) There may be an ovary as well as a testis on one or both sides of the body. In the almost 



