K0.1431. BREEDING HABITS AND EGG OF PIPEFISH— GUDGER. 467 



My own belief is that sperms and ova are emitted simultaneously, and 

 while I have no direct evidence, the followino- facts corroboratory of 

 this conclusion are adduced. 



I believe that the extraordinary ^' liehesspid,''' or pei'iod of sexual 

 excitation of these fishes, described al>ove, is intended to prepare them 

 for the mutual discharge of the sexual products. In the description 

 of the copulation and attendant phenomena, attention has been called 

 to similar sexual excitements in an Amphibian, a (lanoid, and a Cepha- 

 lopod, which are preparatory to the discharge of sperms as well as of 

 egg-s. 



But the second set of phenomena is still more strongly corrobora- 

 tory. On July 0, 1904, two tish were paired and during the night 

 they copulated. They remained in the same aquarium for four da3^«, 

 and then the female was killed, her ovaries excised, cut up, and put 

 into fixing fluids, while some of the ovarian eggs, which fell into the 

 body cavity, were also killed. When these eggs were examined some 

 months later, among them were found two embryos with the blasto- 

 pore closed. None of the other eggs showed an}^ trace whatever of 

 impregnation. Again two lots of eggs, from a male killed in 1902, 

 were examined two years later and found to be in the eight to sixteen- 

 celled stage. In one lot, however, there was found an embryo with 

 black eyes and free tail, and in the other two eggs in which the 

 ])lastoderms covered one-half, the embryos one-fourth, of the circum- 

 ference of the egg. These two lots of eggs had never been removed 

 from the shells, and these shells were still bound together in masses 

 as they came from the pouch. Thus all chance of the eggs having 

 been mixed is eliminated. Again a lot of eggs put up in August, 1904, 

 were found to be in the eight-celled stage, but among them were found 

 two embryos with pectoral fins. 



It is true that in opposite ends of the pouch eggs of different layings, 

 and consequently diiierent ages, are found, but never with difierences 

 of age more than thirty-six hours, against about three to five days in 

 the aljove cases. From these facts I can draw but one conclusion — 

 that at the time of coition both spermatozoa and ova are simultaneoush^ 

 extruded, and, as the female withdraws her oviduct from the button- 

 hole-shaped opening of the marsupium, sperms lodge on it and work 

 their way through it into the ovary and there fertilize eggs. This 

 happens onl}" occasionally, but it seems to me a strong proof of m}^ 

 contention as to the time of fertilization. Gill (1905) quotes Nord- 

 quist, Ehrenbaum, and Eckstroem that internal impregnation occurs 

 occasionally in non-viviparous fishes, such as the Sculpins. See Gill's 

 interesting article on the Sculpin. 



B. ATtificuil fertilization. — This was tried twice by the wet method 

 and once by the dry. The eggs and the torn-up testes were thoroughly 

 mixed in sea water, and after a few minutes were aerated in strained 



