~1 



\ 



Ixxxviii 



T//E BEGINNINGS OF LIFE. 



have derived their 



origin 



from any similar or dissimilar 



existences outside the Volvox, nor could have themselves 

 entered within the sphere by solution^ became very evident 

 from observing the different stages by which the ordinary 

 zoospore gradually arrived ■ to the condition noiv under dis- 

 cussion! After the altered amoeboid zoospore had begun 

 to travel, ' it was always noticed that for every one such 

 moving body in the Volvox there was the empty space of a 

 missing zoospore/ A similar ama3boid change may also 

 overtake such zoospores as have gone on to the first stages 

 of gemmule growth. 



In other cases a very 

 ordinary gemmule growth 



interesting 



deviation from the 

 occurs, which has also been 



the 



increase of the intervening 



mucus. Watching 



throughout the period above mentioned, I found that the seg- 

 mentation continued in various modes till the masses became 

 one-eighth of an inch in diameter, preserving more or less of 

 a globular form, but indefinite so far as any investing mem- 

 brane was concerned. ... At first the division went upon 

 the binary plan ^ ; after which some of them divided into 



1 Dr. Hicks has represented these various changes on PI. IX. of 

 'Journ. of Miciosc. Science,' i£6i. , 



>:.'''"°' J the 



..M 



eters 



(,b.|vidin?' 



■^ 



■It 



these 



incr 

 than the 

 cells AV" 



. W after segn^^ 



:. edge never IK^ 

 e of Cladonn 



...jition commence 



resemblance t< 

 i-m^ of P^r. 



\i 



jfc-' There is als 

 bejmenting gonid 

 additional t 



id in Pritchar 



described by Dr. Braxton Hicks. As a rule the zoospore 

 divides so as to lead to the formation of about thirty-six 

 cells within the common cell-wall. ' These/ Dr. Hicks says, 

 'in the ordinary way would pass on to further subdivision, 

 producing almost from this point ciliated cells, which, again 

 re-dividing, would produce the ultimate zoospores held to- 

 gether* by the hollow, spherical membrane— or, in other 

 terms, the ordinary Volvox. Instead, then, of the' sub-division 

 forming the ciliated cells, which tend towards the exterior of 

 the mass, motionless spores or gonidia are produced, which 

 do not tend outwardly, but which retain their position, i.j'^^'^a great ( 



except that they become more separated from each other by ^■^'^^^ Polyn 



■ H, J, Cailer b 

 "M related to the 

 '^ ■^» Ae actual ' 



'.:S ^nd after i 



?^m 



I 



/■-fori 



'^' ^Wl 



■m 



•i 



°f--i^%i 



the 



'Si\. 



C 



i!>?tt 





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