438 GROWTH AND STKUCTUEE OF T^NIA SAGINATA. 



usual. The calcareous bodies of T. saginata are also, on an average, 

 larger (up to 0018 mm.), and more abundant than in T. solium. 



The Structure of tlie Sexual Organs is best observed in joints of 

 medium size (8 to 10 mm. broad by 4 to 6 mm. long), which are in a 

 moderately contracted state approximately rectangular, and belong to 

 the second half of the seventh hundred. They are found, according to 

 the state of contraction, at a distance of about 40 cm. behind the 

 head. They show the generative organs of both sexes in full develop- 

 ment. The copulation has just taken place, and the eggs are begin- 

 ning to pass into the uterus. 



For the purpose of closer examination the fresh joints should be 

 left for a day in ammoniacal solution of carmine of medium concen- 

 tration. After being clarified in glycerine or balsam, one can see on 

 slight pressure all the parts with great distinctness. Apart from the 

 ducts, this is specially true of the female organs, which, with the 

 exception of the median uterus, all lie in the posterior half of the 

 proglottis, and are quite perceptible by transmitted light even to the 

 naked eye. To examine the more intimate structure it is necessary to 

 have recourse to sections, especially to horizontal ones. 



The Male Organs. — In detail one may note the following char- 

 acters : — 



The Testes are first ripe, and consist, as in most Cestodes, and 

 especially in the larger species, of numerous roundish vesicles, which 

 measure on an average about 0'15 mm. (from 0'12 to 0"18), and which 

 fill up all the vacant space in the joint within the vessels. In the 

 anterior half of the joint they are of course much more numerous 

 than behind, where the female generative organs occupy most of the 

 space. Here they are found chiefly at the sides, as is also the case 

 in the anterior half. The vesicles are therefore larger and more 

 advanced along the two sides than the middle of the joint. 



The contents consist partly of long thin adult spermatozoa, 



which are curled up together in bundles, and usually lie near the 



wall of the vesicle, with their otherwise hardly defined heads resting 



on a granular mass. There are also small round balls of varying size 



up to 0'043 mm., which contain numerous small cells, and represent 



the early developmental stages of the seminal elements. In the larger 



balls one can distinctly observe a large clear sphere (003 mm.) on 



which the cells are seated — a structure which often occurs in the 



lower animals as the bearer of the sperm-cells proper. The cells 



which lie on this to a greater or less extent (nuclei, according to 



Sommer and Landois), may be observed growing into spermatozoa, 



while the central sphere itself finally becomes the above-mentioned 



granular mass. ^. ... ,, .,. „^ 



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