The Amm(d Organism 4rid its Germ-Layers 60 



wherein lie proves tlie actual origin of the sex-cells from 

 the endoderm. The only other positive result which I will 

 touch upon is that concerning the route and cause of 

 migration of the sex-cells from their place of origin to their 

 place of maturing. Goette denies that they have any single 

 road which is the same for all species, as contended by 

 Weismann. He affirms on the contrary, that at least four 

 paths are demonstrable, namely, the gastric endoderm; the 

 bases of the pouches of the radial canal ; the spadix ; and the 

 ectoderm of the manubrium. The kernel of Goette's con- 

 clusion on this subject, as opposed to Weismann's is, as I 

 understand, that the sex-cells arise widely scattered in the 

 parts and tissues of the polypoid colony, and that the de- 

 velopment of the gonads or sex glands consists in large part 

 in the drawing together or concentration of these dissemi- 

 nated elements, in some cases into buds that are to become 

 medusae proper, and in other cases where the medusoid is 

 wholly absent, into the gonophores or brood-sacs which are 

 outgrowths on the polyps. The diversity of the place of 

 origin precludes the possibility of any single "germ track." 



Again Goette does not believe, as Weismann does, that 

 the journeyings of the sex-cells are due wholly to their own 

 independent activity , and considers the comparison of their 

 movements with those of migratory birds, and the ascrip- 

 tion to them of an innate instinct, to be entirely fanciful. 

 He holds, on the contrary, that these cells are largely car- 

 ried along passively by forces which originate in the sur- 

 rounding tissues and structures. His observations on the 

 cells of Podocoryne have, he says, been particularly con- 

 vincing that the wanderings are largely passive, and that 

 even where there is intrinsic movement this is indeterminate 

 as to direction, so that the final goal of the cells is in every 

 case determined chiefly by influences which lie outside the 

 cells themselves. 



What the outside force is which Goette conceives to pro- 



