50 STUDIES IN ANIMAL LIFE. 



plant to designate a vast group of objects which 

 have no powers of locomotion, and then ask, with 

 triumph, How can a plant move? But we have 

 only to enlarge our knowledge of plant-life to see 

 that locomotion is not absolutely excluded from it; 

 for many of the simpler plants Confervse and Al- 

 gge can and do move spontaneously in the early 

 stages of their existence : they escape from their 

 parents as free swimming rovers, and do not settle 

 into solid and sober respectability till later in life. 

 In their roving condition they are called, improper- 

 ly enough, " zoospores,"* and once gave rise to the 

 opinion that they were animals in infancy, and be- 

 came degraded into plants as their growth went on. 

 But locomotion is no true mark of animal-nature, 

 neither is fixture to one spot the true mark of plant- 

 nature. Many animals (Polypes, Polyzoa, Barna- 

 cles, Mussels, etc.), after passing a vagabond youth, 

 " settle" once and forever in maturer age, and then 

 become as fixed as plants. Nay, human animals 

 not unfrequently exhibit a somewhat similar me- 

 tempsychosis, and make up for the fitful capricious- 

 ness of wandering youth by the steady severity of 

 their application to business when width of waist- 

 coat and smoothness of cranium suggest a sense of 

 their responsibilities. 



Whether this loss of locomotion is to be regard- 

 ed as a retrogression on the part of the plant or 

 animal which becomes fixed, may be questioned; 



* Zoospores, from zoon, an animal, and spores, a seed. 



