PARTS CONCERNED IN REPRODUCTION. 23* 



Vegetable Spermatic. 

 Fovilla within the Pollen- 

 tube. 

 Pollen grain. 

 Primary Pollen-cells. 



Parenchyma of Anther. 



Vegetable Genninal. 

 Protoplasmic Corjjuscules. 



Embryo-sac. 

 Nucleus of O^Tile. 

 Ovule. 



§ 3. By way of applying the principles of homological 

 correspondence to the specialities of the several groups of 

 organized beings, a few tabular statements are here sub- 

 joined, based on the notices of the reproductive process in 

 Chapters II. and III. : 



PROTOMORPHIC STAGE. 



The primary product of fecundation, (pro-scolex passing 

 into scolex,) is represented 



In Diatomace?e, by the large frustules. 



In Algse, Fungi, and Lichens, by the composite 



spores. 

 In Mosses and Hepatic?e, by the seta and theca de- 

 veloped from the archegonial cell. 

 In the higher plants, only by the cellular suspensor 

 of the embiyo of the seed. 

 It is^ represented in Animals by the primary germmass, 

 which in many Invertebrata has the characterof a ciliated 

 animalcule. In general it attains no higher organization ; 

 but 



In Echinodermata It is developed into such zooids 



as Auricularia, Pluteiis, and Bipinnaria. 

 In Trematoda, into the primary gregariniform zooid 



(redia or sporocyst). 

 In Cestoidea, into the Cysticerciis or the primary 

 vesicle of the Echinococcus. 



