BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 27. AFD. IV. N:0 6. 27 



placed within the lumen of the genital tube. It varies greatly 

 in shape from spherical to more or less curved and elongated. 

 Treated with iron-hsematoxyline it acquires, the same blackish 

 colour characteristic of the singular body which is mentioned 

 as to be seen within the finely granulated substance of younger 

 ova at the base of the micropyle. When we reflect that the 

 eggs are still in possession of a germinal vesicle with a ger- 

 miual spöt, we see that the corpuscles in question have 

 nothing to do with the extrusion of the polar globules. For 

 my own part I am inclined to consider them as being an ex- 

 cretion from the egg-plasm, and that fig. 12 on my plate I 

 represents an earlier stage, the ovum having not yet thrust 

 it away. 



Aceording to my experience the nearly ripe ovum is kept 

 in position within the follicular säck by means of the micro- 

 pyle-cone being attached to the wall of the säck, which, in its 

 turn, is firmly bound with a broad part of its opposite pole 

 to the inner lining of the genital tube, so as to form a con- 

 tinuous whole with it. In Mesothuria I never observed that 

 the ova are kept in position by any true capsular stalk, such 

 as Semper^ states to be the case in tropic Holothurids, nor 

 have I seen that bundles of fibrilles of connective tissue spin 

 round the ovum in order to keep it fast, as is mentioned by 

 Hamann.- 



In sections of the min ute genital tubes in their earliest 

 developmental stages, the differences between male and female 

 tubes are well pronounced. The male tubes contain, besides 

 smaller follicular cells with oval nucleus, large geminal cells 

 all of almost the same size and pro vid ed with a large rounded 

 nucleus. In female tubes of the same age, on the con- 

 trary, the germinal cells vary greatly in size and contain a 

 large vesicula germinativa with a well developed macula ger- 

 minativa. 



In immature genital tubes, the rather large mother- 

 cells of the spermatozoa are at first arranged in the glens 

 between the folds. In the depths of the glens alone do they 

 seem to be more crowded. By degrees, they multiply so as 

 to form several layers distributed över almost the whole in- 

 side of the tubes in the glens, as well as on the folds them 



1 Op. cit. 



2 Op. cit. 



