236 THE MALE GENERATIVE OEGANS 



away the carapace, leaving the body of the creature as bare as it is 

 possible to be. I then tease out the spermathecce, but cannot 

 always succeed in extracting them whole. The spermathecae are 

 paired organs, somewhat pear-shaped, the membranous tunic 

 being capable of great distension, yet when empty, in consequence 

 of the spermatozoa being used up, become very atrophied — in 

 fact, almost obliterated. They are difficult to preserve. I have, 

 however, succeeded in mounting them in glycerine, after being 

 emptied of spermatozoa by pressure (Fig. 8). When the sperma- 

 theca is filled with spermatozoa, it resembles an old-fashioned ball 

 of cotton, the zooids crossing and re-crossing each other. If a 

 cover-glass be placed gently over them so as not to crush or 

 rupture the tunic, we are able, with a one-eighth inch, to see the 

 mass of spermatozoa in a state of agitation, writhing like innu- 

 merable microscopic worms. It was at this stage that we com- 

 menced jointly our investigations as to their mobility. As has 

 been remarked above, the spermatozoa within the spermatheca 

 was teeming with life, and those in the neighbourhood of the 

 spermathecal aperture exhibited the same vibratory motion. 

 Having satisfied ourselves of their vitality and activity e7i masse, it 

 became necessary to examine them externally and individually. I 

 gently rolled the cover-glass with a needle. This had the desired 

 effect, and the spermatozoa, starting out from the fissure like a 

 number of Gordiidce, kept up an active, wriggling, writhing 

 motion. One fine fellow pushed its way out like a gigantic loop, 

 and kept up a constant action of twisting and untwisting itself 

 This twining and untwining action cannot be otherwise than an 

 "active mobile existence." When a spermatozoon emerges intact, 

 I have invariably noticed that one end, which I called the poste- 

 rior end, was hooked ; the other has four or five turns, like a 

 drawn-out corkscrew, which I call the anterior end (Fig. 4, a^ b).* 



* My reason for applying the terms anterior and posterior is because I 

 have extracted ova with the spermatozoa attached to the ovum. The cork- 

 screw end had entered the micropyle, leaving the hooked end protruding. 

 The zoon had emptied itself of the sperm, was transparent, markings of the 

 coat had faded, and air-globules had entered the empty sheath. These air- 

 globules may have entered the sheath after extraction of ovum from the ovary, 

 and as it lay in the fluid on the glass plate of the dissecting instrument. 



