268 Dynamic Theory. 



A remarkable example of epidemic cholera attacking a mass of putrif ying organic 

 matter, and being communicated from it, is given by Dr. Carpenter in las Physiology. 

 It occurred at the Almshouse, situated two miles from Baltimore, Md., in the summer of 

 1849. The inmates of the establishment numbered 632, of whom 99 died in about a month. 

 The causes of the presence of the disease were discovered to be a mass of putrefying mat- 

 ter from cess-pools, drains, and pig-sties, which had been allowed to find its own way to a 

 drain back of the establishment, but which covered considerable ground on its way 

 thither and had become concealed by a growth of weeds. This stuff was ditched off to 

 the drain, followed by drenching with water; the saturated soil was covered with lime 

 and over that a thick layer of earth. The day after this was done the number of cases of 

 cholera in the almshouse dropped from eleven to three and within two weeks the dis- 

 ease entirely disappeared. The cases were nearly all in the parts of the buildings on the 

 north side, exposed toward this infected ground, and to the wind which generally blew 

 from that direction. Certain rooms on that side which were shielded by nothing more 

 than a barrier of trees escaped. 



CHAPTER XXXII. 



DIFFERENTIATION. 



The term differentiation implies that a homogeneous or mixed whole 

 is divided into two parts which are unlike, as skim-milk and cream. 

 Air is composed of two unlike gases, oxygen and nitrogen, and its 

 properties are the sum of the properties of these components. The an- 

 alysis of air by which the parts are separated from each other, each 

 part taking off from the compound the properties peculiar to itself, is 

 analogous to organic differentiation. The low forms of animal life as 

 the Monera, &c. , l consist of protoplasm, each particle of which is indis- 

 tinguishable from any other particle, and possesses the same properties 

 that any other particle has. It is composed chiefly of carbon, hydro- 

 gen, nitrogen and oxygen, and it has what may be called its positive or 

 native properties, which are the resultant outcome of the properties of 

 the several elements which are included in its make up. Besides these 

 it has other susceptibilities which might be called its negative proper- 

 ties. These consist of its pliability and susceptibility to the influences 

 and movements of the surrounding environment, as touch and pressure, 

 and such forms of energy as heat, light and electricity. It is to the 

 impulses of these outside energies upon the animal that all his move- 

 ments are traceable. His movements are, in fact, only the movements 

 of his environment, diverted, reflected, refracted and reinforced by the 

 chemical forces or positive properties residing in himself. For exam- 

 ple, a certain degree of heat is necessary to enable any sort of move- 

 ment on the part of the animal. If the temperature should sink to 

 "within 5 or 6, centigrade, his power of motion would cease. What may 

 be called the muscular movements of the Moneron are performed by the 

 'extension and contraction of one part or another of its mass of proto- 



1 As a matter of strict fact the Monera are already more or less diff erentiated,but as the 

 differentiations have not gone too far it serves as an illustration. 



