THE BEGINNINGS OF LIFE. 171 



from certain cells or chambers of the parent plant, 

 for a time move about in the water with great activity, 

 before developing into the future plant, are named 

 c zoospores, 3 and also c gonidia.' The nature and mode 

 of origin of these bodies were most carefully studied by 

 M. Thuret 1 , and the investigation has since been fol- 

 lowed up by many other observers. They seem to be 

 always produced as a result of differentiations taking 

 place in a previously formless protoplasm, and in their 

 free active stage of existence they closely resemble 

 certain infusorial animalcules, though, of course, they 

 differ from these altogether as regards their ultimate 

 fate. As Dr. Lindley pointed out 2 : c The reproduc- 

 tion of algals by zoospores is a much more common 

 phenomenon than has been supposed. Instead of being 

 confined to the lower forms of the alliance, it occurs in 

 the most completely organized forms, such as Lami- 

 narias, which are hardly more remarkable for their 

 gigantic size than for the complexity of their structure/ 

 One mode of formation and liberation of these bodies 

 is well described by Agardh. He says 3 : c The fila- 

 ments of Conferva area are, as is well known, articu- 

 lated or divided at equal distances into little compart- 

 ments (joints), which have no communication among 

 themselves other than what results from the per- 

 meability of the dissepiments. The green matter 



1 Ann. des Sc. Naturelles. S6r. 3, t. xiv. 

 a ' Vegetable Kingdom,' 3rd edition, p. n. 

 3 Ann. des Sc. Naturelles,' 1836, t. xii. p. 194. 



