690 REPORT— 1891. 



rock, but it will require the crumbling of this world to obliterate the truths that 

 have been taught by Charles Darwin. 



3. The Ciliated Organs of the Leeches. Bij Professor Gilson. 



Tt is well known that the segmental organ of the Chetopods terminates in the 

 coelom iu the form of a funnel-shaped and ciliated structure. 



In the leeches, on the contrary, though it is generally taught that there exists 

 a similar feature, our knowledge of it is imperfect. 



Se^'eral authors confess that they have not been able to detect in these worms 

 any relation between the segmental organ and certain ciliated bodies that have 

 been regarded by others as terminal funnels or nephridiostome. 



I have undertaken with one of my pupils. Dr. Bolsius, several researches in 

 order to resolve if possible that interesting question. I shall content myself with 

 an extremely short account of the results we arrived at up to the present as 

 regards the genus Nephelis. 



Tlie ciliated organs of the Nephelis are not funnel- but cup-shaped bodies, with 

 a non-perforated bottom. The sides of the cup are composed of large bilobed 

 cells. The bottom, on the contrary, consists only of smaller and non-ciliated cells. 



This cup lies enclosed in the cavity of a large vesicle, from the sides of which it 

 vibrates freely, being only suspended bj- a small number of large connective cells. 

 The vesicle is only a dilatation of one of these non-contractile blood-vessels that 

 represent, according to the view of Dr. Bourne, the greatly modified coelom of the 

 leeches. It lies at a certain distance from the segmental organ, and is ordinarily 

 separated from the same by muscles or connective cells. 



The result of these observations is that the ciliated organs of the Nephelis 

 deserve by no means the name of funnels, and that there is no anatomical 

 connection between them and the segmental gland. 



We can assert also that this gland does not open into the coelom, at least not 

 in certain genera of leeches, and especially the Nephelis, as it does in the well- 

 known case of the Chetopods. 



The absence of connection between the ciliated bodies and the segmental 

 gland seems to be a result of the profound modification the coelom undergoes 

 in these remarkable forms of annelids. 



The terminal or coelomic part of the segmental organ is separated from the 

 rest of the gland, and as this separation is not followed by immediate degeneration 

 of the nephridiostome, it seems evident that the latter — that is to say, the cup- 

 shaped organ — acquires at the same time a new significance and another 

 physiological function. 



As regards this new function we may propose two hypotheses which do 

 not exclude each other : — 



1. The cilia cause the blood to run through the non-contractile capillaries; 

 at least they help its motion through the coelomic system. 



2. The organ is a place of proliferation of the blood-cells. — In fact the 

 cup-shaped organ is ordinarily crowded with blood-corpuscles, the nuclei of which 

 are often remarkable for their chromatophile power. We detected also amongst 

 them several phases of karyocinesis. 



These results, I think, are noteworthy for anyone who is interested with 

 the position of the formation and evolution of the segmental organs and with the 

 kidney-theory. They will soon be published in full in the Louvain Review 

 ' La Cellule.' 



4. Some Points in the Early Development of Mus muscuhis and Mus decu- 

 manus : the Relation of the Yolk Sac to the Decidua and the Placenta. 

 By Arthur Robinson, M.D. 



1. At the seventh day the ovum consists of a large yolk sac and a small mass 

 of primitive epiblast which rests upon one pole of the ovum. The ovum is con- 



