103(5 



SUBMAMMALIAN VERTEBRATES 



others. The testis of the perch is smallest 

 from late June to late August (northern hem- 

 isphere). Spermatogenesis then proceeds 

 rapidly enough so that by early November 

 the gonad has reached its greatest size 

 (Turner, 1919). In the stickleback, Gaster- 

 osteus pungitius, spermatogenesis occurs in 

 the winter and spring (van Oordt, 1924) , but 

 it extends through the autumn, winter, and 

 spring in G. aculeatus (Courrier, 1921c, 

 1922a, b; Craig-Bennett, 1931). Testicular 

 volume, an indicator of spermatogenetic 

 rate, in the top-minnow, Gambusia affinis, 

 in summer is eight times as great as in 

 winter (Geiser, 1922). In Fundulus sperma- 

 togenesis is at its height in late May, June, 

 and July (Matthews, 1938). The process 

 l)t'gins in June or July in the salmon parr, 

 Salmo solar, and ripe sperm have accumu- 

 lated by October or November (Jones, 

 1940; Jones and Orton, 1940). (A parr is a 

 young salmon which has not yet migrated 

 to the sea.) This fish, incidentally, may be 

 pacdogenetic, i.e., it may spawn before be- 

 coming adult (Jones and Orton, 1940). In 

 Brachijraphis episcopi, related to Gambusia, 

 on the other hand, reproductive cycles may 

 occur in any month (Turner, 1938a). 



In higher orders of fish spermatogenesis 

 occurs in testicular lobules which are the 

 homologues of the seminiferous tubvdes of 

 the amniotes (Oslund, 1928). It is common 

 for the ripe sperm to form balls or cysts 

 within the testes (Conel, 1917; Turner, 

 1919; Okkelberg, 1921; Geiser, 1922; Os- 

 lund, 1928; Vaupel, 1929; Matthews, 1938). 

 In the basking shark, Cetorhinus maximus, 

 cilia rotate the masses of sperm into balls 

 while testicular epithelial cells secrete con- 

 centric layers of investing material. The 

 resulting spermatophore is 2 to 3 cm. or 

 more in diameter (Harrison Matthews, 

 1950). The sperm ball of Lebistes reticu- 

 latus contains thousands of germ cells; their 

 tails are directed toward the center and 

 intertwine to hold the ball together (Vaupel, 

 1929 ) . The cephalic end of the mesonephros 

 of the elasmobranch Chimaera secretes a 

 substance which similarly agglutinates the 

 sperm into a spermatophore (Parker and 

 Burlend, 1909). 



Sperm storage in the male has been re- 

 ported in Gambusia. This fish breeds from 



spring until September, and again in No- 

 vember, spermatozoa remaining in the testis 

 for release the following spring (Self, 1940). 



Spawning occurs in the early spring in 

 the three-spined stickleback, Gasterosteus 

 aculeatus aculeatus (Ikeda, 1933), and in 

 the spring and early summer in the carp and 

 goldfish (Scruggs, 1951), top-minnow (Car- 

 ranza and Winn, 1954), perch (Turner, 

 1919), and striped bass (Pearson, 1938). In 

 Fundulus, sperm are shed in June, July, 

 and even August (Matthews, 1938). Fertili- 

 zation is internal in the basking shark, 

 Cetorhinus maximus, the clasper being used 

 as an intromittent organ; mating occurs in 

 late spring and early summer (Harrison 

 Matthews, 1950). Eels spawn in the spring 

 and summer. The wonderful story of their 

 migration from as far away as Europe to the 

 breeding grounds in the western Atlantic 

 Ocean and of the eventual return of the 

 young, sometimes again to rivers 3000 feet 

 above sea level in Switzerland, is one of the 

 most remarkable known to naturalists. The 

 eel's migration was described by the Danish 

 biologist, Jobs. Schmidt (1922) ; the reader 

 is urged to consult his paper. 



Gerbil'skii's (1955) studies of sturgeons 

 {Acipenser giildenstddti, A. stellatus, and 

 Huso huso) reveal that within each species 

 there may be several "biologic races." The 

 time of spawning of the race depends on 

 the river system in which the race lives and 

 may vary by several months from the 

 spawning time of other races of the same 

 species. Temperature is believed to be one 

 of the factors involved. 



Atrophy of the testis in old age has 

 been reported in the myxinoids Bdellostoma 

 and Mijxine (Conel, 1917) and in a teleost, 

 Astyanax mexicanus (Rasquin and Hafter, 

 1951). 



Amphibians 



In Salamandra, the female may be in- 

 seminated at any time between February 

 and October (Baylis, 1939). Spermatogene- 

 sis occurs in Tritunis in summer and early 

 fall. The testes reach their maximal size 

 in July and August. Actual mating, how- 

 ever, is deferred until the period from April 

 through June, the mature sperm being stored 

 over the winter (Adams, 1940). Eurycea 



