36 



observed, were produced through the agency of an irritable 

 and contractile cellular tissue, in which nothing peculiar could 

 be detected ; and were influenced, like many in the animal 

 world, by chemical re-agents — such as prussic acid, strychnia 

 and opium. No nervous system could be detected in these 

 plants, and it was evident that their irritability depended upon 

 something else. The plates of the Diatomese moved upon 

 each other only under the stimulus of light, which appeared 

 to influence amazingly the motions of all contractile vegetable 

 tissues. In the spores of the " conferva glomerata" we had 

 a phenomenon of locomotion of a most extraordinary 

 description ; depending upon a contractile beak, which 

 moved up and down with astonishing rapidity. A spore of 

 this kiud might well be taken for an animal, had it not been 

 seen to settle in a dark corner and begin to vegetate. It 

 consisted of a transparent envelope, of a round shape, but 

 contracted into an elongated point at one part. In the body 

 of the cell was contained a quantity of green viscous mate- 

 rial, of a homogeneous character, which stopped abruptly at 

 tbe beak. 



The Author then proceeded to describe the phenomenon 

 of muscular contraction in the animal world — contrasting 

 the voluntary with the involuntary motions, and the different 

 effects produced by chemical, and other stimuli, upon the one 

 and the other — and showing the great difference which existed 

 in the minute anatomy of the muscles producing them. 

 Wherever the tissue peculiar to voluntary muscle was found 

 (with the solitary exception of the heart) the organ was 

 more or less under the influence of the will ; and wherever 

 the involuntary fibre was found, the will had no effect in 

 producing contraction, although mental emotions (as fear, 

 joy, disgust) produced a marked effect. These muscles 

 existed only in the higher forms of life, as they were absent in 

 the lowest infusoria. In the latter, voluntary motion appeared 

 to reside in a structureless transparent membrane, which 



