160 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



same investigator, spermatopLores were first seen in Eupagurus by Schwainiuerdain 

 in 1752, and were observed in tbe Brachyura also by Oavoliui in 1792. They were 

 rediscovered by Kolliker in 1841. 



SPEKM CELLS. 



The sperm cells of the lobster were apparently seen for the first time by Valentin, 

 in September, 1837 {192), and he gave a brief account of his discovery in the following 

 year. A more accurate account by Kolliker, who also remarked on the apparent 

 immobility of the " rayed cells," appeared in 1843 (109). 



The structure and genesis of tbe spermatozoa of the lobster have been studied 

 with much detail by Grobben (83), Gilson (77), Hermann (89), and more recently by 

 Sabatier (173). 



Each sperm cell (fig. 129, plate 37) consists of a cylindrical and partially hollow 

 column or shaft, surmounted with a rounded dome, on what may be called the superior 

 end. Between the capital and shaft three long, slender processes are given off, making 

 an angle of 120° with each other. The processes are sharp-pointed, rigid, and very 

 slender. The stiffness of the rays has led to the erroneous view that the rayed con- 

 dition represented an immature stage in the maturation of the cell. The sperm cells 

 withdrawn from the spermatic receptacle where they have lain weeks or months are 

 still rayed, although the processes are often broken off or very limp (fig. 129, a). 

 Apropos to this subject Grobben (83) says: 



The stiffness of the rays does not prove that these cells are completely immobile. Moreover, 

 the observation of Owsjaunikow that the, rays sometimes draw themselves in, and certain structures 

 which Ihave examined, enableme to conclude definitely that these rays are living protoplasm and that 

 they represent amoeboid processes, remaining almost in a state of rest. [Compare the observation 

 of Cano quoted on p. 49.] 



The genesis of the sperm cells from the spermatoblasts has been satisfactorily 

 determined in most particulars, but there are some questions, which concern both this 

 and the structure of the adult sperm cell, which are still undecided. The conclusion of 

 Sabatier that the rayed cells become enucleated in the course of their growth can 

 hardly be accepted. Sabatier has suggested that the stiff rays may serve at first to 

 stick the cells together. 



Nothing is definitely known either as to how the spermatophores are conveyed to 

 the seminal receptacle or how the spermatozoa reach the eggs and fertilize them. 



