ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 747 



tissue and the basal membrane, either separately or by groups, into 

 the epidermal cells, wliere they take up their definite position. There 

 appear to be a larger number of rhabditcs in more sensitive than in 

 less sensitive parts of the body. The basal membrane is more or less 

 well developed in all Turbellarians. The characters of the musculature 

 are discussed in detail, and the differences between the three species 

 examined are pointed out. 



The mesenchym contains imbedded in itself unicellular glands, 

 which are most numerously developed behind the brain, and above 

 and below the enteric canal. Their function is either mucous or 

 salivary ; but it is by no means certain that the latter are comparable 

 to the similarly named glands of higher animals. In young embryos 

 the space between the epidermis and the enteric epithelium is occu- 

 pied by a solid mass of connective-tissue cells, which are partly 

 massed into syncytia, and are partly separated by cell-boundaries. In 

 the adult the arrangement is very different, owing to the appearance 

 of a larger number of pseudo-coelomic spaces, which communicate with 

 one another, and force the nuclei away from one another, and so give 

 rise to branching cells of connective tissue and a general appearance 

 of reticulation. In the living animal the lacunar spaces are probably 

 filled with the so-called perivisceral fluid, which possibly serves as a 

 carrier for the nutriment prepared within the enteric cells. Dendro- 

 coelum lacteum has, as its name implies, none of its connective tissue 

 pigmented, as is the case in a number of other forms. 



The author confirms in many points the descriptions given by his 

 predecessors as to the characters of the digestive organs ; in D. 

 lacteum he finds that there are 26-34, in PL polychroa 22-28, and in 

 Pol. tenuis 15-19 pairs of lateral branches to the intestine, of which 

 10-15, 9-13, and 4-6 respectively belong to the primary trunk of the 

 gut. All but those at either end branch dichotomously. His account 

 of his own observations on the excretory organs is prefaced by a 

 statement of what has been done by recent observers ; the point to 

 which he himself directs express attention is the undoubted fact of 

 the presence of cilia in the lumen of certain capillaries ; in the 

 median part of the body they are best developed, and take a coiled 

 course ; their movement is definite in direction, and these ciliated 

 vessels have nothing to do with the cilfated infundibula. Many of 

 these vessels are so fine that, were it not for their cilia, they would 

 be invisible. The ciliated infundibula arc not numerous in, at any 

 rate, young specimens, and are often widely sepai'ated from ono 

 another. The presence of excretory vacuoles was recognized, and 

 they were seen to be, like the vacuoles of the Protozoa, clear during 

 life ; they give some indications of containing products of uric 

 excretion. 



After a very detailed description of the generative organs, the 

 nei-vous system is taken up. This was studied by the light of Lang's 

 investigations, the general results of which are fully confirmed. 

 Jijima liad no difficulty in convincing himself of tho existence of a 

 plexus of fine nerves on the dorsal surface, lying just beneath the 

 inner longitudinal fibres of the dermal musculature. As in other 



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