THE BEGINNINGS OF LIFE. 391 



refractive granules frequently make their appearance 

 within the mucus-layer of the cell • and when the former 

 shrinks from the latter, these spherical cells become 

 wrapped up in it.' Each of the spherical cells usually 

 develops a blind tube, which sometimes penetrates the 

 cell wall of the Spirogyra for the exterior liberation of 

 its contained germs, though others of them may commu- 

 nicate with adjacent cells. And occasionally one of these 

 inosculating spherical cells may send its tube ^through 

 the septum of the cell into the resting-spore of the 

 next cell, which, being full of nutritious matter, im- 

 mediately furnishes food for the whole brood.' Mr. 

 Carter says that the granules of the tubulating cells 

 are of different sizes, and motionless at first; though 

 they subsequently 'become locomotive, swarm about 

 the cell, and then pass out of the tubular prolonga- 

 tions.' Cells of an altogether similar character were 

 also seen to develop within the dead bodies of certain 

 Rotifers ^ 



^ Concerning the actual origin of these products Mr. Carter has exhi- 

 bited much vacillation of opinion. Thus, although at one time he 

 believed they were formed from a modification of the substance of the 

 organism in which they appeared, he afterwards renounced this view and 

 adopted his first notion that they were parasites whose germs had been 

 introduced ('Ann. of Nat. Hist.' 1861, pp. 285-28S). But tubulating 

 germ cysts of a somewhat similar nature have been seen by Stein within 

 Vorticella microstoma and Vorticella nebuH/er a. f^see Pritchard's ' Infusoria,' 

 P' 357) ; ^^d they were thought by Stein to represent one of the modes 

 of reproduction of these Infusoria — which seems to show that they 

 appeared to him to be formed from the very substance of the organism 

 in which they were found. Cienkowski has also observed a similar 

 development of brood cells within encysted specimens of Nassula viridis 



