516 GROWTH AND DEVELOPMENT OF T^NU SOLIUM. 



especially by the uterus.^ It is evident that the joints with prepon- 

 derating breadth have either no eggs in the uterus, or but few. It is 

 in the square joints that the eggs, which accumulate iu increasing 

 numbers as the uterus lengthens out, pass through their embryonic 

 development. But it is only in the extended proglottides of the last 

 metre that the eggs acquire their brown shells and the uterus its 

 final form. Only these last joints exhibit the characteristic dendritic 

 structure and colour of the uterus, which are directly evident to the 

 observer through the thin and almost transparent body -substance 

 The number of these " ripe " joints is at most about 100. 



The study of the structure of the sexual organs is therefore im- 

 portant, especially in the examination of the short proglottides. Even 

 before the end of the first length of 25 cm., Avhich includes, indeed, 

 half of the total number of joints, the sexual organs begin to appear. 

 It takes 25 to 35 cm. before they are fully formed. Then copulation 

 takes place, which is succeeded by the passage of the eggs into the 

 uterus and the beginning of the embryonic development. 



In order to obtain more data for the decision of the question 

 whether these measurements and proportions have a specific or indi- 

 vidual importance, I have lately examined another well-preserved 

 specimen of Taenia solmni. The worm was somewhat more strongly 

 contracted than the one first measured, being only 175 cm. long, while 

 possessing about an equal number of joints. Before the middle of 

 the body a breadth of 7'5 mm. was attained. 



The segmentation began at a distance of 3 mm. behind the head, 

 which was 1 mm. thick, but it was at first faint and difi&cult to de- 

 monstrate, so that I have only approximately estimated the number 

 of joints in the first centimetre at 65. The second centimetre con- 

 tained 80, the third 57, the fourth 32, and the fifth 41— altogther 414 

 in the first 5 cm., almost as many as in the other 170 cm. of the body ! 

 The small number of joints in the fourth centimetre was explained by 

 the fact that it had undergone an unusual extension, so that some of its 

 joints measured 0'3 mm., — much more than in the following portion, 

 in which even those at the end did not exceed 0"2 mm. In the three 

 previous portions the length of the joints rose to 008, O'l, and 017, 

 and the breadth to 07, 1, and 1"6 mm. respectively. The fourth much 

 extended portion showed the same breadth at its termination, the fifth 

 a breadth of 2'5 mm. Thence the size of the joints increased so 

 rapidly that the next length of 20 cm. exhibited only 229 segments, — 



' We must also remember that the form of the joints is largely — though here less 

 strikingly than in the very muscular Tcsnia aayinata — determined by the state of con- 

 traction exhibited by the worm, a fact which prevents any absolute accuracy in these 

 measurements. 



Digitized by Microsoft® 



