ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 785 



portion, represented by a contractile utriculus, which often extends 

 throughout the whole length of the body, and ends at the caudal 

 foramen ; (2) a median portion, consisting of branches of a medium 

 size ; and (3) a peripheral portion, formed by a capillary plexus which 

 penetrates all the organs and the parenchyma of the body. 



In discussing the different morphological interpretations of these 

 parts, the author expresses his opinion that the theory of Prof. Ray 

 Lankester, according to which a portion represents the ccelom and 

 the rest the nephridium, rests on an arbitrary distinction, inasmuch as 

 there is nothing in the Platyhelminthes which corresponds to the 

 internal orifices of the segmental organs of Annelids ; nor does the 

 author find the explanations of Fraipont either satisfactory or new. 

 Indeed, M. Villot is of opinion that later works have exhibited rather 

 a step backwards ; the presence of a coeloni and of true segmental 

 organs in these worms still remains to be demonstrated ; the vascular 

 apparatus consisting of a single system of vessels, which are perfectly 

 continuous and open only to the exterior or into the enteron. 



Anatomy of Cestodes.* — Dr. Z. von Eoboz has examined Soleno- 

 phorus megalocephalus. In dealing with the cuticular structures, 

 he finds that the cells forming the so-called subcuticular layer are 

 connected both with one another and with the cuticle by a fairly well- 

 developed, finely granulated, intercellular substance, in which fine 

 fibrils of connective tissue are to be distinguished. The constituent 

 cells differ in form in different parts, for, while they are elongated in 

 the older joints, and have a finely granular protoplasm with a distinct 

 nucleus and nucleolus, they are spindle-shaped in the scolex and the 

 younger joints, and are connected by processes with the cuticle on 

 the one hand and the interior of the body on the other ; the forms of 

 these processes may vary considerably. 



In regard to the water-vascular system, the most interesting dis- 

 covery of the author would appear to be the demonstration of a special 

 musculature for the longitudinal canals and their branches, an arrange- 

 ment which seems to have escaped the observation of all previous 

 investigators. The following will give some idea of what has been 

 observed as to the nervous system : — Four nerve-cords are, altogether, 

 given off from the ganglioniform enlargements which pass into one 

 another at the region of the two suckers, and so give rise to the 

 formation of a nerve-ring. Finer branches are thence given off, some 

 of which pass into the suckers, while others give rise to the primary 

 cords which pass into the proglottids ; the connection between the 

 nerve-branches is such as to give rise to a nerve-plexus embracing the 

 whole of the scolex. 



It has been found that the oviduct is not merely formed by a thin 

 homogeneous membrane, but that it is invested by an epithelium ; 

 from the separate cells special hair-like structures, which call to mind 

 cilia, project into the lumen of the tube ; but that they are really cilia 

 was negatived by the length of time that the material for exam- 

 ination had been preserved. The vas deferens appears to be formed 



* Zeitschr. f. wiss. Zool., xxxvii. (1882) pp. 263-85 (2 pis.). 



