22 THÉEL, HERMAPHRODISM IN HOLOTHURIDS. 



génitaux atrophiés ou en voie de développement)". From the 

 above quotations it becomes evident that Bördas himself was 

 in great doubt as to the true function of these small bodies. 

 In my opinion, there is not the least doubt but that they 

 only represent the youngest and least developed forms of 

 geni tal tubes, and that they have nothing at all to do with 

 secreting glands in the strictest sense of the word. 



With regard to the elementary tissues which compose 

 the genital tubes, I have nothing of importance to add to our 

 present knowledge of them. I only intend to call attention 

 to the most obvious and neglected transformations of the 

 general arrangements to which the tubes are subjected during 

 the ripening process of the sexual products. In very young 

 tubes, both male and female, there is to be found an aggre- 

 tion of cells of two different kinds : large sexual cells in diff er- 

 ent stages of karyokinesis, this being especially the case with 

 the male cells, and smaller ones which have as their end to 

 gradually arrange themselves around the eggs in order to 

 form the follicle-membrane and, moreover, to form the inter- 

 nal epithelial lining of the tubes. At this early period, 

 scarcely a lumen is visible, nor are any folds to be detected. 

 Considering that the afEux of nutritious fluid is very sparse 

 at that period, it is very probable that the increasing sexual 

 cells procure their nourishment through the surrounding cells. 

 By degrees, the tubes, invested exteriorly by a ciliated epi- 

 thelium, grow larger, their lumina become wider and their 

 walls commence to increase in thickness and, simultaneously, 

 to give off a series of longitudinal folds hanging down into 

 the cavity of the tubes. The sexual cells arrange themselves 

 successively in such a manner, that they finally become pla- 

 ced in the glens between the outgrowing folds, which gra- 

 dually become expanded to such a high degree that they 

 finally conceal the sexual cells and fill up the cavity of the 

 tubes (Pl. I, figs. 9, 10). 



The folds in question are sparingly strengthened by con- 

 nective tissue. Their growth is mainly due to the abundant 

 afflux of blood w^hich causes them to swell, and the increasing 

 germinal cells are certainly in pressing need of the nutri- 

 tious fluid in their immediate neighbourhood. In sections 

 across a tube, the folds present themselves as transparent and 

 nearly structureless protrusions. Treated with hsematoxyline, 



