37 



was eminently contractile. This contractility was consi- 

 dered to be entirely independent of any nervous system, 

 and to be simply an attribute existing during life ; it 

 was not found in the young of the Paramcecia prior to its 

 separation from the parent, or in any animalculy after they 

 had been killed by pressure or chemical re-agents. 



In the Hydra Viridis, the whole body was eminently 

 contractile, and the property necessarily resided in the 

 cellular tissue, of which it was composed, as there was 

 neither fibre nor membrane to be discovered. This 

 animalcule had the faculty of causing its prey to adhere to 

 the surface of its tentacles, the action being evidently 

 voluntary and instinctive, as other things were allowed to 

 pass by unheeded. 



There were, however, in the animal economy, other 

 motions which did not come either under the category 

 of voluntary or involuntary. There was, for example, 

 the contraction in the arterial tissue, by which each tube 

 was enabled to adapt its calibre to the quantity of blood 

 it contained. 



There was, also, a curious contractile power noticed in 

 the scrotum of the male, and the nipple of both sexes, which 

 resided in the pure cellular or areolar tissue there contained; 

 though it was worthy of remark, that precisely similar 

 structure elsewhere was non-contractile. This was entirely 

 removed from the influence of the nervous system, local 

 stimulation only producing any marked effects. 



A membrane existing at the posterior part of the bronchi 

 had been proved to be contractile under stimulation, 

 although no muscular fibres could be detected in it. It 

 was the contraction of this membrane, under the effects of 

 an irritating atmospheric air, that produced the pheno- 

 menon of asthma. 



There was yet another set of motions in the animal 

 world which had for a long time escaped detection, in 



