ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 731> 



The glandular epithelium of tlio kiduey is distinguished, at first 

 sight, from that of the liver by the wider and less elongated form of the 

 cells which compose it ; as in all the glands, thuse cells are arranged in 

 a single layer ; the texture of the protoplasm is reticulated or spongy in 

 the region of the nucleus, while the apical part has a more complex and 

 very variable structure. In each cell oue sees one to three balls of a 

 very granular substance, distinctly yellowish in colour ; there may also 

 be, though they are rarer, colourless bodies. The ajjical part of the 

 cell is very fragile, and it is almost impossible to get really sitisfactory 

 sections; there do not appear to be cilia in the renal cells, for Lacaze- 

 Duthiers, Plate, and the author have all failed to find them. 



The gonads are exceedingly simple, being in the form of a longi- 

 tudinal fascicle, which has on its lateral edges a number of dilatations; 

 the sac has a delicate wall, and is, primarily, closed. There are no 

 traces at all of hermaphroditism. The gonad of the adult contains cells 

 in all stages of ditfereutiation, but the transition is always made in the 

 most sim^jle and natural manner, " sans aucune de ces complications 

 romanesques qu'il est de mode de trouver et de rendre incomprehensibles 

 h I'aide d'une nomenclature qui varie a la fantaisie de chaque auteur." 

 With regard to the vexed question of the presence of an eiferent duct to 

 the gonads, the author says that there is no doiibt as to the existence of 

 the excretory canal which Lacaze-Duthiers described as extending along 

 the whole length of the gonad, but it is not a canal from the histological 

 point of view ; it is merely an excavation of the axial part of the gonad 

 and its lobes, hollowed out in the genital products and quite devoid of 

 any epithelial or cuticular membrane. The canal may be followed in a 

 series of sections, but it can only be seen when the sexual products are 

 on the point of maturity. 



The author concludes with an account of the tentaculiform filaments, 

 but does not find himself able to speak definitely of their morphology ; 

 he endorses, therefore, Lacaze-Duthiers' condemnation of the group- 

 name, Cirribranchiata, which has been proposed for Dentalium, and 

 states that he is in comjjlete accord with that naturalist as to the 

 systematic position of the genus. 



S. liamellibranohiata- 



Movements of Bivalve Mollusca.*— Mr. D. M- Alpine communicates 

 some observations on the movements of the entire detached animal, and 

 of detached ciliated parts of bivalve molluscs, viz. gills, mantle-lobes, 

 labial palps, and foot ; these studies were made on Mi/tilus edulis. He 

 finds that the entire animal, when removed from the shell, moves, the 

 movements being rotatory, and at an average of fifteen minutes per round ; 

 the power of movement was retained for twenty-one hours in one case 

 and fifty and a half in another. Detached mantle-lobes, gills, labial 

 palps, and foot, either entire or in parts, also move. These the author 

 describes in some detail. The movements are not entirely due to the 

 action of cilia, for muscular contraction plays a most important role in 

 altering the shape and dimensions of the part, and in giving it outlines 

 which enable it to get rid of obstacles or to make a more judicious use 

 of its motive power. The ciliary and other activity of all these parts is 

 stimulated by direct mechanical irritation. It appears that there is just 



* Pro?. E. S'oc. Edinb., xv. (18S7-8) pp. 17.3-204, 



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