TAPE-WORMS OF THE SUr,-FA:\[ILY AVITETJJNIN.F. 329 



the most fifty, eggs, measuring 14^* iu diameter j it atrophies 

 very rapidly after the appearance of the uterus. (Woiffhiigel's 

 figure only shows the uteri, which have been erroneously 

 labelled ovarium by him.) The ovarium measures 86 ju in 

 diameter. 



The oviduct, the uterine duct and the canalis seminalis 

 meet a short distance from the receptaculum seminis, as in 

 Avitellina. Thei-e is no vitelline gland, nor shell-gland. 

 The function of the missing yolk-cells is exercised by abortive 

 eggs iu the ovarium (ovarial nutritive cells, see p. 371), and 

 by cells derived from the uterine walls (uterine nutritive cells, 

 see p. 375) . The eggs in the uterus are firmly embedded in the 

 uterine nutritive cells, as has also been observed by Fuhrmann 

 (1909), who already suggested that their function is probably 

 nutritive; however, contrary to his supposition, the uterus is 

 originally hollow. The uterus measures 50 /t to 8(3 /{ ; the eg'gs 

 are finally enclosed iu paruterine organs similar to the par- 

 uterine organ described as occurring in Avitellina (seep. 

 375). The paruterine organ arises within the uterus ; each seg- 

 ment contains two paruterine organs, one within each uterus. 

 They measure 50 ju to 86 fi. The uteri and later on the par- 

 uterine organs are connected by a band of fibrous tissue, Avhicli 

 covers the uterus anteriorly, passes through into the median 

 field and tapers off toAvards the middle of the segment, the two 

 halves of the band meeting in the middle. Their course across 

 the segment is not quite direct, the middle portion drooping 

 towards the posterior end of the proglottid. The eggs are 

 enclosed in two envelopes, the outer of which invariably 

 appears wrinkled whilst the inner is always smooth and 

 rounded. The inner envelope seems to possess a prolongation 

 at each pole (perhaps due to optical delusion and not existent; 

 it is almost impossible to get rid of the outer envelope so as 

 to examine the inner properly). The eggs, measured over 

 the outer shell, are 26 /j. long by 16 to Id fx broad, the embryo 

 15 to 16 ^<. 



AYolffhugel states the size of the eggs as 26^/ xl6f.i, 

 Fuhrmann as 16 /x (evidently only the embryo) ! 



