436 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Histology. — (a) The tubular portion of tlie testes is lined by a 

 homogeneous, nucleated membrane, without distinguishable cell- 

 boundaries, while the vesicular portion is lined by a characteristic 

 pavement epithelium. The muscular layer is also much more distinct 

 in the latter portion. (6) In the spermatogenesis the following 

 stages are distinguishable : (1) large " spermatospores " or " Samenur- 

 mutterzellen " ; (2) separate "spermatoblasts" or " Samenmutter- 

 zellen," resulting from the repeated division of the former ; (3) im- 

 mature sperms, with nucleus elongating to form the middle portion, 

 and with protoplasm forming the long tail. A small protoplasmic 

 remnant, of unknown import, persists for long near the anterior end. 

 (c) The vasa efferentia arise, with a very narrow neck, from the 

 vesicular testis, are closely coiled, and enveloped in a muscular 

 peritoneal sheath, (^d) The unpaired portion of the male ducts, the 

 vas deferens, has the striking length of 7 cm., and exhibits three 

 distinct portions — (1) a thin walled portion containing a mass of 

 loose sperms ; (2) a middle region in which the spermatophor is found ; 

 (3) a terminal, markedly muscular ductus ejaculatorius. All three 

 portions exhibit a peritoneal sheath with tracheae, a muscular layer, a 

 tunica propria, and internal epithelium. The middle region, which 

 is lined with well-developed cylindrical epithelium, and with distinct 

 cilia, contains the long, cylindrical spermatophor. This consists of a 

 central rod of agglutinated spermatozoa, surrounded by several pro- 

 tective sheaths, some of which, at least, owe their origin to the 

 epithelium of the vas deferens. Near the proximal end, the originally 

 simple sheath of the spermatophor tube splits into two, while the 

 epithelial cells of the vas deferens becomes more markedly cylindrical, 

 and exhibit cilia and granular contents. About 1 cm, from the end 

 the spermatophor canal widens out, compressing the enveloping 

 sheaths. Between the first and second of three to five similar swell- 

 ings, some of the epithelial cells of the vas deferens are peculiarly modi- 

 fied ; the nuclei increase, spherical secreted bodies (" Secretkugeln ") 

 are formed, the cells become distinctly glandular, and the ciliated 

 cells are much compressed. The secreted balls enter the vas deferens 

 and form a layer round the spermatophor. None are formed after the 

 second expansion. The spermatophor seems to be shifted periodically 

 forwards for a distance equal to that between two enlargements, and 

 thus successive portions are enveloped by the products of the glandular 

 cells. 



0. Crural Glands. — While Moseley found crural glands on all 

 legs of P. capensis, both in male and female, these structures were 

 altogether absent in the female P. Edivardsii, and were present only 

 in some segments of the male. Dr. Gaffron describes the appearance 

 and distribution of these glands, which he regards as ectodermal 

 invaginations. 



D. Anal Glands. — The male is further characterized by the 

 possession of a pair of glandular tubes in the anal region. They 

 open ventrally on each side of the anus, and are doubtless identical 

 with those noted by Moseley as " accessory generative glands." Each 

 gland exhibits a distinct ectodermal and endodermal portion, separated 



