74 mCller on the male of 



ing. The substance is little altered by a diluted solution of 

 caustic soda. 



The innermost coat of the ductus deferens is generally formed 

 by a layer which strongly refracts light, and when it is stretched 

 looks like a tubular brittle glassy membrane. 



Elsewhere when collapsed it has the appearance of a longitudi- 

 nally fibrous cord,which is easily torn transversely into fragments, 

 and only the local dilatations (for example from 0*02 of a line in 

 diameter to quite smooth clear vesicles of 0*2 of a line in diameter) 

 show its tubular character. One portion is frequently invagi- 

 nated for a certain distance in a funnel-shaped expanded portion 

 behind it, whereby a swelling is produced. In other places the 

 innermost layer forms the spiral band mentioned by Kolliker. 

 This exhibits considerable elasticity, and its coils are often 

 very close, often far separated, which depends upon the form 

 of the penis. The band has sometimes the appearance of a 

 spirally cut delicate tube, sometimes that of a cylinder, like the 

 snake-toys which are cut out of horn. 



Next to this innermost layer the mass of the ductus deferens 

 appears to be longitudinally striated to an irregular extent. Ex- 

 ternally again it becomes circularly striated, and not unfre- 

 quently some layers appear to be more sharply distinguished 

 from the rest. In the midst some portion will frequently be 

 found wholly structureless, and quite external to the ductus 

 deferens ; a strongly marked layer has again all the characters of 

 a so-called vitreous membrane. 



In the penis the whole ductus deferens, without reference 

 to its contained spiral band, sometimes forms spiral coils of 

 much greater extent, in which the outer layers of the penis take 

 but little part. 



Many modifications of the ductus deferens occur which appear 

 to indicate different stages of development. Instead of the 

 usually tolerably solid enlargement at its commencement (Kol- 

 liker, pi. 2. fig. 11 d), there exists at times a somewhat large 

 pyriform body which attains a few lines in length, and the larger 

 it is so much the softer are its contents. In its axis, however, one 

 can already distinguish the commencement of the inner denser 

 tube, which further on in the ductus deferens incloses or forms 

 the spiral band. 



