4 2 



EDGAR DAVIDSON CONGDON. 



constituting the spadix wall are in contact with the egg at one 

 end since the spadix lies directly against the egg membrane. 

 At their other end they extend for varying distances into the 

 lumen producing a folded surface not unlike a digestive epi- 

 thelium. It is probable that this large free surface is important 

 in augmenting the absorption of food which is passed on to the 



egg (Fig- n)- 



Two views have obtained as to the way in which the hydroid 

 egg takes up the cells. Balfour's text-book of embryology, pub- 



^i V;&' c$ ' ::^:- ; - v w^ 



^ 



w *(i' ?; 



' 





^? ^----^^--vT'i Ji^ 1 "^ 



FIG. ii. 



lishecl in 1879, states that they are amoeboid and do so by putting 

 up pseudopodia. Metchinkoff in 1887 described such a method 

 in some medusae. Tichomiroff in the same year found a condi- 

 tion in certain hydroid eggs which he terms an " amceboides 

 Fressen." Smallwood, '99, saw indications of amceboid activities 

 in the egg of Pcnnaria tiarclla. 



A different conception as to the process of absorption is found 

 in Doflein's account, '96, of the development of the egg of Titbn- 

 larin larynx. It is apparent from his discussion that he has 

 studied the question carefully. He concludes that although eggs 

 have processes like pseudopodia, there is no amoeboid movement. 

 Absorption occurs by the breaking down of the walls of the egg 

 and adjacent cells to form a syncytium-like structure. When the 



