192 Dynamic Theory. 



the Chlorophyl organism to its plant ( or animal ) is one of mutual de- 

 pendence and helpfulness. The eell of the plant is the shelter, bed- 

 room and workshop of the active Chlorophyl body which amply pays 

 for its lodging in starch. There is another party belonging to this com- 

 bination one Diastase a ferment and an organism, which will be de- 

 scribed further on, which is an equall}' valuable member of the firm and 

 which the plant could not get along without, since it takes the insoluble 

 starch and makes it into sugar. These mutually cooperative organisms 

 of the vegetable have their counterparts in every animal, which is, in- 

 deed, after all only a locomotive vegetable. The different sorts of cells 

 which compose the animal body may be regarded as a cooperative com- 

 munity of separate organisms, each living its own life and in some way 

 helping the rest, yet dependent upon the rest for its existence and pre- 

 servation. In this partnership there are blood corpuscles, the cells 

 composing the various tissues, muscle, bone, nerve, skin, &c. , and a 

 dozen different kinds of ferments which inhabit special parts called 

 glands. The relations and mutual adaptations of these several organ- 

 isms toward each other have come about through their habit of living 

 together and acting upon each other through an infinite series of genera- 

 tions. As long as they are properly nourished and not interfered with 

 by strange and adventitious organisms from the outside, the bod}- which 

 they compose remains in a healthy and normal condition. But the 

 nourishment that is good for the cells and ferments that belong to the 

 body is also good for the many strange organisms that infest the air, 

 the water and the ground, and are always ready to get a foothold in the 

 body and compete with the normal* household for a share. They not 

 only do this but they compete with one another. One species of para- 

 site or, in some cases, even one individual, may be an antidote against 

 all others, keeping the others away by some sort of competition, as rats 

 keep away mice, or as vaccine keeps off small-pox. 



There are many species of the Bopyridse, a Crustacean family, that is 

 parasitic on other Crustaceans, as crabs, or tailed Crustaceans, living in 

 their branchial or gill cavities. But the first comer that establishes him- 

 self in the cavity on one side is a bar to the intrusion of any more either 

 in that side or in the other (Semper). This is singular, but is proved 

 by many examples. Why is this? One theorj" is that the first parasite 

 exhausts the peculiar food necessary for their support so there is not 

 enough for the second. A second is that the first parasite occupies the 

 avenues of approach to the food supply in the host, so that while the 

 food is there it is inaccessible to a new comer, as Kentucky Blue-grass 

 will root out sand- burrs, not by exhausting the soil but by occupying 

 its whole surface and cutting off access to it. I suggest a third, which 

 is that the action of the first parasite changes the nature of the secre- 



