BY T. HARVEY JOHNSTON, M.A., D.SC, F.L.S. 79 



fcerine organ developing rapidly. At first it is a short, 

 narrow, longitudinally-placed, more or less median, mass 

 of tissue, becoming tubular. The position of the uterus 

 undergoes alteration, this organ being gradually displaced 

 so as to lie in the posterior part of the proglottid, though 

 occasionally it remains in the middle of the segment as a 

 very large simple sac with numerous ripe eggs within it. 

 The anterior part of the paruterine organ undergoes 

 differentiation to form an expanded rounded capsule, 

 the tubular portion becoming wider and more sinuous. 

 This cajjsule is sharply marked off from the surrounding 

 tissues, especially laterally and anteriorly. It increases 

 in size and ultimately occupies most of the medulla of 

 the anterior part of the segment. Its dimensions while 

 within the proglottis vary from .22 by .14 mm to .30 

 by .24 mm. Some which had been extruded from the 

 segment measured .4 by .3 mm. 



The capsule consists of an outer coarse layer which 

 stains very deeply with eosin and of an inner zone which 

 retains the hsematoxylin dye. It is within the latter 

 that the eggs come to lie imbedded. The outer layer 

 does not cover the posterior face of the capsule, the egg- 

 containing tissues being in continuit}^ with the paruterine 

 organ, through which the eggs have travelled from the uterus 

 to the capsule. The peripheral region of the inner zone 

 of the capsule possesses numerous rod-like structures re- 

 sembling crystalloids, but they do not polarise light. Eggs 

 may occur in this perij^heral area. A few fusiform granular 

 bodies were seen in this layer in several capsules. 



The paruterine organ has a vacuolate appearance 

 and has what seems to be an axial series of nuclei. The 

 contents of the tube appear to be albuminous. 



Ripe eggs are to be found in the capsule and more 

 or less commonly in the uterus. 



They measure from .035 by .030 mm to .040 by .035 

 mm., the contained OTicosphere being about .024 mm. in 

 diameter. The embryonal booklets are .010-. 012 mm 

 long, with a long claw whose length is equal to the distance 

 between the dorsal and ventral roots. 



