Haswett—A Monograph of the Temnocephalee. 125 
deferens leaves the posterior testis. From this point they run nearly transversely, 
close to the vas deferens, until they reach the dilated bulb of the cirrus, into which 
they open. In 7. Dendyz the strands of ducts combine as they near the base of the 
cirrus and end in a dilatation (PI. xu. fig. 7, 2 g. 2. and 7 g. ~.), in which the rounded 
particles become aggregated together into irregular clumps. In the others the 
aggregation appears to take place in the interior of the bulb of the cirrus itself. 
In the Rhabdoceles glands of this kind (the so-called “ Kérnerdriisen,” or 
“prostate glands”) are of general occurrence, and v. Graft’s account of them in that 
group would apply fairly well to Zemnocephala. In certain Trematodes similar glands 
have also been found. Saint Rémy* describes them as occurring in the 772stomide. 
and the Udonelide -—“ Chez les Tristomides et les Udonellides (et aussi chez 
Calicotyle dapres Wierzejsky) il existe des glandes spéciales séerétant un liquide 
destiné & se méler aux spermatozoides : dans ces deux familles ces glandes prostatiques 
déversent leur produit dans un réservoir communiquant avec le canal ejecteur 
(vesicule prostatique) 
not described. 
” 
But the position and histological structure of the glands are 
XII.—Tue SperMaroGEnsgsis. 
The spermatogenesis was studied in specimens treated by a variety of different 
methods. The best results were got by treating fresh specimens with methyl green ; 
and by sections and teased preparations fixed by Flemming’s method and stained with 
alum-cochineal. The former method was found very useful for other elements as 
well—the mode of procedure being as follows:—A live specimen was placed on a 
slide with the ventral surface upwards and covered with a cover glass so as to be 
slightly compressed. Watery solution of methyl green containing a little acetic 
acid was run in, allowed to act for an hour or more, and then washed out with water 
acidulated with acetic acid. A slight compression might then be required in order to 
cause the discharge of the contents of the testes. Good results were also obtained 
by staining hardened specimens with picrocarmine and teasing out in dilute glycerine. 
The mode of development of the spermatozoa differs somewhat from what is 
observable in other Trematodes. In sexually immature individuals the testis consists 
of a mass of cells about ‘015mm. in diameter (PI. xu. fig. 1) with large nuclei with a dense 
network of chromatin and two small nucleoli, and with a comparatively small amount 
of cytoplasm. In the mature testis spherical or sub-spherical masses of cells, about 
* Comptes Rendus, T. CXVII. (1891), 
